[Refactor ] Refactored motor state in preparation for debugging the simulation itself

- Created MotorState as an enum describing discrete states a motor may be in
- moved ThrustCurveMotorState info back into MotorSimulation
  -- MotorSimulation will be used by the simulation code.
  -- tracks simulation-time info, such as event times, and current state ( <MotorState> )
- MotorConfiguration no longer have any knowledge about their simulation info
- moved functionality (BUT NOT STATE) into ThrustCurveMotor
  -- can query about thrust(t), mass(t), cgx(t)

core/src/net/sf/openrocket/masscalc/MassCalculator.java

@@ -25,25 +25,37 @@ public class MassCalculator implements Monitorable {
 	public static enum MassCalcType {
 		NO_MOTORS {
 			@Override
-			public Coordinate getCG(Motor motor) {
-				return Coordinate.NUL;
+			public double getCGx(Motor motor) {
+				return 0;
+			}
+			@Override
+			public double getMass(Motor motor) {
+				return 0;
 			}
-			
 		},
 		LAUNCH_MASS {
 			@Override
-			public Coordinate getCG(Motor motor) {
-				return motor.getLaunchCG();
+			public double getCGx(Motor motor) {
+				return motor.getLaunchCGx();
+			}
+			@Override
+			public double getMass(Motor motor) {
+				return motor.getLaunchMass();
 			}
 		},
 		BURNOUT_MASS {
 			@Override
-			public Coordinate getCG(Motor motor) {
-				return motor.getEmptyCG();
+			public double getCGx(Motor motor) {
+				return motor.getBurnoutCGx();
+			}
+			@Override
+			public double getMass(Motor motor) {
+				return motor.getBurnoutMass();
 			}
 		};
 		
-		public abstract Coordinate getCG(Motor motor);
+		public abstract double getMass(Motor motor);
+		public abstract double getCGx(Motor motor);
 		
 		/**
 		 * Compute the cg contribution of the motor relative to the rocket's coordinates
@@ -52,16 +64,21 @@ public class MassCalculator implements Monitorable {
 		 * @return
 		 */
 		public Coordinate getCG(MotorConfiguration motorConfig) {
-			Coordinate cg = getCG(motorConfig.getMotor());
-			cg = cg.add(motorConfig.getPosition());
+			Motor mtr = motorConfig.getMotor();
+			double mass = getMass(mtr);
+			Coordinate cg = motorConfig.getPosition().add( getCGx(mtr), 0, 0, mass);
 			
 			RocketComponent motorMount = (RocketComponent) motorConfig.getMount();
-			Coordinate totalCG = new Coordinate();
+			Coordinate totalCM = new Coordinate();
 			for (Coordinate cord : motorMount.toAbsolute(cg) ) {
-				totalCG = totalCG.average(cord);
+				totalCM = totalCM.average(cord);
 			}
 
-			return totalCG;
+			return totalCM;
+		}
+		
+		public Coordinate getCM( Motor motor ){
+			return new Coordinate( getCGx(motor), 0, 0, getMass(motor));
 		}
 	}
 	
@@ -168,7 +185,7 @@ public class MassCalculator implements Monitorable {
 			double motorXPosition = mtrConfig.getX();  // location of motor from mount
 
 			
-			Coordinate localCM = type.getCG( mtr );  // CoM from beginning of motor
+			Coordinate localCM = type.getCM( mtr );  // CoM from beginning of motor
 			localCM = localCM.setWeight( localCM.weight * instanceCount);
 			// a *bit* hacky :P
 			Coordinate curMotorCM = localCM.setX( localCM.x + locations[0].x + motorXPosition );

core/src/net/sf/openrocket/motor/Motor.java

@@ -1,9 +1,6 @@
 package net.sf.openrocket.motor;
 
-import net.sf.openrocket.simulation.MotorState;
-import net.sf.openrocket.util.Coordinate;
-
-public interface Motor {
+public interface Motor extends Cloneable {
 	
 	/**
 	 * Enum of rocket motor types.
@@ -118,12 +115,19 @@ public interface Motor {
 	
 	public String getDigest();
 	
-	public MotorState getNewInstance();
+	public Motor clone();
 	
-	public Coordinate getLaunchCG();
+	// this is probably a badly-designed way to expose the thrust, but it's not worth worrying about until 
+	// there's a second (non-trivial) type of motor to support...
+	public double getThrustAtMotorTime( final double motorTimeDelta );
 		
-	public Coordinate getEmptyCG();
+	public double getLaunchCGx();
 	
+	public double getBurnoutCGx();
+	
+	public double getLaunchMass();
+	
+	public double getBurnoutMass();
 	
 	/**
 	 * Return an estimate of the burn time of this motor, or NaN if an estimate is unavailable.

core/src/net/sf/openrocket/motor/MotorConfiguration.java

@@ -4,7 +4,6 @@ import net.sf.openrocket.rocketcomponent.FlightConfigurableParameter;
 import net.sf.openrocket.rocketcomponent.IgnitionEvent;
 import net.sf.openrocket.rocketcomponent.MotorMount;
 import net.sf.openrocket.rocketcomponent.RocketComponent;
-import net.sf.openrocket.simulation.MotorState;
 import net.sf.openrocket.util.Coordinate;
 import net.sf.openrocket.util.Inertia;
 
@@ -16,6 +15,7 @@ public class MotorConfiguration implements FlightConfigurableParameter<MotorConf
 	
 	public static final String EMPTY_DESCRIPTION = "Empty Configuration";
 
+	// set at config time
 	protected MotorMount mount = null;
 	protected Motor motor = null;
 	protected double ejectionDelay = 0.0;
@@ -41,30 +41,10 @@ public class MotorConfiguration implements FlightConfigurableParameter<MotorConf
 		modID++;
 	}
 	
-	public MotorState getSimulationState() {
-		MotorState state = motor.getNewInstance();
-		state.setEjectionDelay( this.ejectionDelay );
-		if( ignitionOveride ) {
-			state.setIgnitionEvent( this.ignitionEvent );
-			state.setIgnitionDelay( this.ignitionDelay );
-		} else {
-			MotorConfiguration defInstance = mount.getDefaultMotorInstance();
-			state.setIgnitionEvent( defInstance.ignitionEvent );
-			state.setIgnitionDelay( defInstance.ignitionDelay );
-		}
-		state.setMount( mount );
-		state.setId( id );
-		return state;
-	}
-	
 	public boolean hasIgnitionOverride() {
 		return ignitionOveride;
 	}
 	
-	public boolean isActive() {
-		return motor != null;
-	}
-	
 	public String getDescription(){
 		if( motor == null ){
 			return EMPTY_DESCRIPTION;
@@ -164,7 +144,7 @@ public class MotorConfiguration implements FlightConfigurableParameter<MotorConf
 
 	public double getPropellantMass(){
 		if ( motor != null ) {
-			return (motor.getLaunchCG().weight - motor.getEmptyCG().weight);
+			return (motor.getLaunchMass() - motor.getBurnoutMass());
 		}
 		return 0.0;
 	}

core/src/net/sf/openrocket/motor/ThrustCurveMotor.java

@@ -8,16 +8,13 @@ import java.util.Locale;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import net.sf.openrocket.util.ArrayUtils;
 import net.sf.openrocket.util.BugException;
 import net.sf.openrocket.util.Coordinate;
+import net.sf.openrocket.util.Inertia;
 import net.sf.openrocket.util.MathUtil;
 
-
 public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Serializable {
-	/**
-	 * 
-	 */
+	// NECESSARY field, for this class -- this class is serialized in the motor database, and loaded directly.
 	private static final long serialVersionUID = -1490333207132694479L;
 
 	@SuppressWarnings("unused")
@@ -45,13 +42,18 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 	private final double length;
 	private final double[] time;
 	private final double[] thrust;
-	private final Coordinate[] cg;
-	
+//	private final double[] cgx;   // cannot add without rebuilding the motor database ... automatically on every user's install.
+//	private final double[] mass; // cannot add without rebuilding the motor database ... on every user's install.  
+	private final Coordinate[] cg; /// @deprecated, but required b/c the motor database is serialized java classes.
 	private double maxThrust;
 	private double burnTime;
 	private double averageThrust;
 	private double totalImpulse;
 	
+	private final double unitRotationalInertia;
+	private final double unitLongitudinalInertia;
+	
+	
 	/**
 	 * Deep copy constructor.
 	 * Constructs a new ThrustCurveMotor from an existing ThrustCurveMotor.
@@ -63,19 +65,22 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 		this.designation = m.designation;
 		this.description = m.description;
 		this.type = m.type;
-		this.delays = ArrayUtils.copyOf(m.delays, m.delays.length);
+		this.delays = Arrays.copyOf(m.delays, m.delays.length);
 		this.diameter = m.diameter;
 		this.length = m.length;
-		this.time = ArrayUtils.copyOf(m.time, m.time.length);
-		this.thrust = ArrayUtils.copyOf(m.thrust, m.thrust.length);
-		this.cg = new Coordinate[m.cg.length];
-		for (int i = 0; i < cg.length; i++) {
-			this.cg[i] = m.cg[i].clone();
-		}
+		this.time = Arrays.copyOf(m.time, m.time.length);
+		this.thrust = Arrays.copyOf(m.thrust, m.thrust.length);
+		this.cg = m.getCGPoints().clone();
+//		this.cgx = Arrays.copyOf(m.cgx, m.cgx.length);
+//		this.mass = Arrays.copyOf(m.mass, m.mass.length);
 		this.maxThrust = m.maxThrust;
 		this.burnTime = m.burnTime;
 		this.averageThrust = m.averageThrust;
 		this.totalImpulse = m.totalImpulse;
+		
+		this.unitRotationalInertia = m.unitRotationalInertia;
+		this.unitLongitudinalInertia = m.unitLongitudinalInertia;
+
 	}
 	
 	/**
@@ -162,8 +167,19 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 		this.time = time.clone();
 		this.thrust = thrust.clone();
 		this.cg = cg.clone();
+//		this.cgx = new double[ cg.length];
+//		this.mass = new double[ cg.length];
+//		for (int cgIndex = 0; cgIndex < cg.length; ++cgIndex){
+//			this.cgx[cgIndex] = cg[cgIndex].x;
+//			this.mass[cgIndex] = cg[cgIndex].weight;
+//		}
+		unitRotationalInertia = Inertia.filledCylinderRotational( this.diameter / 2);
+		unitLongitudinalInertia = Inertia.filledCylinderLongitudinal( this.diameter / 2, this.length);
 
 		computeStatistics();
+
+		// This constructor is not called upon serialized data constructor.
+		//System.err.println("loading motor: "+designation);
 	}
 	
 	
@@ -186,6 +202,65 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 		return time.clone();
 	}
 	
+	/* 
+	 * find the index to data that corresponds to the given time:
+	 *  
+	 * Pseudo Index is two parts: 
+	 *     integer : simple index into the array
+	 *     fractional part:  [0,1]: weighting to interpolate between the given index and the next index. 
+	 *  
+	 * @param is time after motor ignition, in seconds
+	 * @return a pseudo index to this motor's data. 
+	 */
+	public double getPseudoIndex( final double motorTime ){
+		final double SNAP_DISTANCE = 0.001;
+		
+		if( time.length == 0 ){
+			return Double.NaN;
+		}
+		
+		if( 0 > motorTime ){
+			return 0.0;
+		}
+		
+		int lowerBoundIndex=0;
+		int upperBoundIndex=0;
+		while( ( upperBoundIndex < time.length ) && ( motorTime >= time[upperBoundIndex] )){
+			++upperBoundIndex;
+		}	
+		lowerBoundIndex = upperBoundIndex-1;
+		if( upperBoundIndex == time.length ){
+			return time.length - 1; 
+		}
+		
+		if ( SNAP_DISTANCE > Math.abs( motorTime - time[lowerBoundIndex])){
+			return lowerBoundIndex;
+		}
+		
+		double lowerBoundTime = time[lowerBoundIndex];
+		double upperBoundTime = time[upperBoundIndex];
+		double timeFraction  = motorTime - lowerBoundTime;
+		double indexFraction = ( timeFraction ) / ( upperBoundTime - lowerBoundTime );
+
+		if( indexFraction < SNAP_DISTANCE ){
+			// round down to last index
+			return lowerBoundIndex;
+		}else if( indexFraction > (1-SNAP_DISTANCE)){
+			// round up to next index
+			return ++lowerBoundIndex;
+		}else{
+			// general case 
+			return lowerBoundIndex + indexFraction;
+		}
+	}
+	
+	@Override
+	public double getThrustAtMotorTime( final double searchTime ){
+		double pseudoIndex = getPseudoIndex( searchTime );
+		return getThrustAtIndex( pseudoIndex ); 
+	}
+
+	
 	/**
 	 * Returns the array of thrust points for this thrust curve.
 	 * @return	an array of thrust samples
@@ -194,14 +269,26 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 		return thrust.clone();
 	}
 	
-	/**
-	 * Returns the array of CG points for this thrust curve.
-	 * @return	an array of CG samples
-	 */
-	public Coordinate[] getCGPoints() {
+//	/**
+//	 * Returns the array of CG points for this thrust curve.
+//	 * @return	an array of CG samples
+//	 */
+//	public double[] getCGxPoints() {
+//		return cgx;
+//	}
+	
+	public Coordinate[] getCGPoints(){
 		return cg.clone();
 	}
 	
+//	/**
+//	 * Returns the array of Mass values for this thrust curve.
+//	 * @return	an array of Masses
+//	 */
+//	public double[] getMassPoints() {
+//		return mass;
+//	}
+	
 	/**
 	 * Return a list of standard delays defined for this motor.
 	 * @return	a list of standard delays
@@ -221,6 +308,25 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 		return type;
 	}
 	
+	public double getUnitLongitudinalInertia() {
+		return this.unitLongitudinalInertia;
+	}
+	
+	public double getUnitRotationalInertia() {
+		return this.unitRotationalInertia;
+	}
+
+	public double getIxxAtTime( final double searchTime) {
+		final double index = getPseudoIndex( searchTime); 
+		//return this.unitLongitudinalInertia * this.getMassAtIndex( index);
+		return this.unitLongitudinalInertia * this.getCGAtIndex( index).weight;
+	}
+	
+	public double getIyyAtTime( final double searchTime) {
+		final double index = getPseudoIndex( searchTime); 
+		//return this.unitRotationalInertia * this.getMassAtIndex( index);
+		return this.unitRotationalInertia * this.getCGAtIndex( index).weight;
+	}
 	
 	@Override
 	public String getDesignation() {
@@ -248,29 +354,104 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 		return length;
 	}
 	
-	
 	@Override
-	public ThrustCurveMotorState getNewInstance() {
-		return new ThrustCurveMotorState(this);
-	}
-	
-	
-	@Override
-	public Coordinate getLaunchCG() {
-		return cg[0];
+	public ThrustCurveMotor clone() {
+		return new ThrustCurveMotor(this);
 	}
 	
 	@Override
-	public Coordinate getEmptyCG() {
-		return cg[cg.length - 1];
+	public double getLaunchCGx() {
+		return cg[0].x;//cgx[0];
 	}
 	
-	//   Coordinate getCG(int index)
-	//   double getThrust( int index)
-	//   double getTime( int index)
+	@Override
+	public double getBurnoutCGx() {
+		return cg[cg.length - 1].x;// cgx[ cg.length - 1];
+	}
+	
+	@Override
+	public double getLaunchMass() {
+		return cg[0].weight;//mass[0];
+	}
+	
+	@Override
+	public double getBurnoutMass() {
+		return cg[cg.length-1].weight; //mass[mass.length - 1];
+	}
+	
+	private static double interpolateValueAtIndex( final double[] values, final double pseudoIndex ){
+		final double SNAP_TOLERANCE = 0.0001;
+
+		final double upperFrac = pseudoIndex%1;
+		final double lowerFrac = 1-upperFrac;
+		final int lowerIndex = (int)pseudoIndex;
+		final int upperIndex= lowerIndex+1;
+
+		// if the pseudo 
+		if( SNAP_TOLERANCE > (1-lowerFrac) ){
+			// index ~= int ... therefore:
+			return values[ (int) pseudoIndex ];
+		}else if( SNAP_TOLERANCE > upperFrac ){
+			return values[ (int)upperIndex ];
+		}
+		
+		final double lowerValue = values[lowerIndex];
+		final double upperValue = values[upperIndex];
+		
+		// return simple linear interpolation
+		return ( lowerValue*lowerFrac + upperValue*upperFrac );
+	}
+
+	public double getThrustAtIndex( final double pseudoIndex ){
+		return interpolateValueAtIndex( this.thrust, pseudoIndex );	
+	}
+	
+	public double getMotorTimeAtIndex( final double index ){
+		return interpolateValueAtIndex( this.time, index );
+	}
+
+	@Deprecated
+	public Coordinate getCGAtIndex( final double pseudoIndex ){
+		final double SNAP_TOLERANCE = 0.0001;
+
+		final double upperFrac = pseudoIndex%1;
+		final double lowerFrac = 1-upperFrac;
+		final int lowerIndex = (int)pseudoIndex;
+		final int upperIndex= lowerIndex+1;
+
+		// if the pseudo 
+		if( SNAP_TOLERANCE > (1-lowerFrac) ){
+			// index ~= int ... therefore:
+			return cg[ (int) pseudoIndex ];
+		}else if( SNAP_TOLERANCE > upperFrac ){
+			return cg[ (int)upperIndex ];
+		}
+		
+		final Coordinate lowerValue = cg[lowerIndex].multiply(lowerFrac);
+		final Coordinate upperValue = cg[upperIndex].multiply(upperFrac);
+		
+		// return simple linear interpolation
+		return lowerValue.add( upperValue );
+	}
+
+	
+//	public double getCGxAtIndex( final double index){
+//		//return interpolateValueAtIndex( this.cgx, index );
+//		
+//	}
+//	
+//	public double getMassAtIndex( final double index){
+//		//return interpolateValueAtIndex( this.mass, index );
+//		
+//	}
+	
+	
+	
+	//   int getCutoffIndex();
+	
 	//   double getCutoffTime()
 	//   int getCutoffIndex();
-	//   double interpolateThrust(...)
+
 	//   Coordinate interpolateCG( ... ) 
 	
 	//
@@ -304,7 +485,7 @@ public class ThrustCurveMotor implements Motor, Comparable<ThrustCurveMotor>, Se
 	}
 	
 	public double getCutOffTime() {
-		return this.time[this.time.length - 1];
+		return time[time.length - 1];
 	}
 	
 	/**

core/src/net/sf/openrocket/motor/ThrustCurveMotorPlaceholder.java

@@ -1,8 +1,6 @@
 package net.sf.openrocket.motor;
 
-import net.sf.openrocket.simulation.MotorState;
 import net.sf.openrocket.util.BugException;
-import net.sf.openrocket.util.Coordinate;
 
 public class ThrustCurveMotorPlaceholder implements Motor {
 	
@@ -75,20 +73,10 @@ public class ThrustCurveMotorPlaceholder implements Motor {
 	}
 	
 	@Override
-	public MotorState getNewInstance() {
+	public Motor clone() {
 		throw new BugException("Called getInstance on PlaceholderMotor");
 	}
 	
-	@Override
-	public Coordinate getLaunchCG() {
-		return new Coordinate(length / 2, 0, 0, launchMass);
-	}
-	
-	@Override
-	public Coordinate getEmptyCG() {
-		return new Coordinate(length / 2, 0, 0, emptyMass);
-	}
-	
 	@Override
 	public double getBurnTimeEstimate() {
 		return Double.NaN;
@@ -184,4 +172,30 @@ public class ThrustCurveMotorPlaceholder implements Motor {
 				+ ", designation=" + designation + "]";
 	}
 	
+	@Override
+	public double getLaunchCGx() {
+		return length / 2;
+	}
+
+	@Override
+	public double getBurnoutCGx() {
+		return length / 2;
+	}
+
+	@Override
+	public double getLaunchMass() {
+		return launchMass;
+	}
+
+	@Override
+	public double getBurnoutMass() {
+		return emptyMass;
+	}
+
+
+	@Override
+	public double getThrustAtMotorTime(double pseudoIndex) {
+		return 0;
+	}
+	
 }

core/src/net/sf/openrocket/motor/ThrustCurveMotorState.java

@@ -1,257 +0,0 @@
-package net.sf.openrocket.motor;
-
-import net.sf.openrocket.models.atmosphere.AtmosphericConditions;
-import net.sf.openrocket.rocketcomponent.IgnitionEvent;
-import net.sf.openrocket.rocketcomponent.MotorMount;
-import net.sf.openrocket.simulation.MotorState;
-import net.sf.openrocket.util.BugException;
-import net.sf.openrocket.util.Coordinate;
-import net.sf.openrocket.util.Inertia;
-import net.sf.openrocket.util.MathUtil;
-
-public class ThrustCurveMotorState implements MotorState {
-	//	private static final Logger log = LoggerFactory.getLogger(ThrustCurveMotorInstance.class);
-	
-	private int timeIndex = -1;
-	
-	protected MotorMount mount = null;
-	protected MotorInstanceId id = null;
-	private double ignitionTime = -1;
-	private double ignitionDelay;
-	private IgnitionEvent ignitionEvent;
-	private double ejectionDelay;
-	
-	
-	protected ThrustCurveMotor motor = null;
-	
-	// Previous time step value
-	private double prevTime = Double.NaN;
-	
-	// Average thrust during previous step
-	private double stepThrust = Double.NaN;
-	// Instantaneous thrust at current time point
-	private double instThrust = Double.NaN;
-	
-	// Average CG during previous step
-	private Coordinate stepCG = Coordinate.ZERO;
-	// Instantaneous CG at current time point
-	private Coordinate instCG = Coordinate.ZERO;
-	
-	private final double unitRotationalInertia;
-	private final double unitLongitudinalInertia;
-	
-	//  // please use the Motor Constructor below, instead.
-	//	@SuppressWarnings("unused")
-	//	private ThrustCurveMotorInstance() {
-	//		unitRotationalInertia = Double.NaN;
-	//		unitLongitudinalInertia = Double.NaN;
-	//	}
-	
-	public ThrustCurveMotorState(final ThrustCurveMotor source) {
-		//log.debug( Creating motor instance of " + ThrustCurveMotor.this);
-		this.motor = source;
-		this.reset();
-		
-		unitRotationalInertia = Inertia.filledCylinderRotational(source.getDiameter() / 2);
-		unitLongitudinalInertia = Inertia.filledCylinderLongitudinal(source.getDiameter() / 2, source.getLength());
-		
-	}
-	
-	@Override
-	public ThrustCurveMotorState clone() {
-		try {
-			return (ThrustCurveMotorState) super.clone();
-		} catch (CloneNotSupportedException e) {
-			throw new BugException("CloneNotSupportedException", e);
-		}
-	}
-
-	@Override
-	public double getIgnitionTime() {
-		return ignitionTime;
-	}
-
-	@Override
-	public void setIgnitionTime(double ignitionTime) {
-		this.ignitionTime = ignitionTime;
-	}
-
-	@Override
-	public MotorMount getMount() {
-		return mount;
-	}
-
-	@Override
-	public void setMount(MotorMount mount) {
-		this.mount = mount;
-	}
-
-	@Override
-	public IgnitionEvent getIgnitionEvent() {
-		return ignitionEvent;
-	}
-
-	@Override
-	public void setIgnitionEvent(IgnitionEvent event) {
-		this.ignitionEvent = event;
-	}
-
-	@Override
-	public double getIgnitionDelay() {
-		return ignitionDelay;
-	}
-
-	@Override
-	public void setIgnitionDelay(double delay) {
-		this.ignitionDelay = delay;
-	}
-
-	@Override
-	public double getEjectionDelay() {
-		return ejectionDelay;
-	}
-
-	@Override
-	public void setEjectionDelay(double delay) {
-		this.ejectionDelay = delay;
-	}
-
-	@Override
-	public void setId(MotorInstanceId id) {
-		this.id = id;
-	}
-
-	@Override
-	public MotorInstanceId getID() {
-		return id;
-	}
-
-	public double getTime() {
-		return prevTime;
-	}
-	
-	public Coordinate getCG() {
-		return stepCG;
-	}
-	
-	public Coordinate getCM() {
-		return stepCG;
-	}
-	
-	public double getPropellantMass(){
-		return (motor.getLaunchCG().weight - motor.getEmptyCG().weight);
-	}
-	
-	public double getLongitudinalInertia() {
-		return unitLongitudinalInertia * stepCG.weight;
-	}
-	
-	public double getRotationalInertia() {
-		return unitRotationalInertia * stepCG.weight;
-	}
-	
-	@Override
-	public double getThrust() {
-		return stepThrust;
-	}
-	
-	@Override
-	public boolean isActive() {
-		return prevTime < motor.getCutOffTime();
-	}
-	
-	public Motor getMotor(){
-		return this.motor;
-	}
-	
-	public boolean isEmpty(){
-		return false;
-	}
-	
-	@Override
-	public void step(double nextTime, double acceleration, AtmosphericConditions cond) {
-		if (MathUtil.equals(prevTime, nextTime)) {
-			return;
-		}
-		
-		double[] time = motor.getTimePoints();
-		double[] thrust = motor.getThrustPoints();
-		Coordinate[] cg = motor.getCGPoints();
-		
-		if (timeIndex >= (motor.getDataSize() - 1)) {
-			// Thrust has ended
-			prevTime = nextTime;
-			stepThrust = 0;
-			instThrust = 0;
-			stepCG = motor.getEmptyCG();
-			return;
-		}
-		
-		
-		// Compute average & instantaneous thrust
-		if (nextTime < time[timeIndex + 1]) {
-			
-			// Time step between time points
-			double nextF = MathUtil.map(nextTime, time[timeIndex], time[timeIndex + 1],
-					thrust[timeIndex], thrust[timeIndex + 1]);
-			stepThrust = (instThrust + nextF) / 2;
-			instThrust = nextF;
-			
-		} else {
-			
-			// Portion of previous step
-			stepThrust = (instThrust + thrust[timeIndex + 1]) / 2 * (time[timeIndex + 1] - prevTime);
-			
-			// Whole steps
-			timeIndex++;
-			while ((timeIndex < time.length - 1) && (nextTime >= time[timeIndex + 1])) {
-				stepThrust += (thrust[timeIndex] + thrust[timeIndex + 1]) / 2 *
-						(time[timeIndex + 1] - time[timeIndex]);
-				timeIndex++;
-			}
-			
-			// End step
-			if (timeIndex < time.length - 1) {
-				instThrust = MathUtil.map(nextTime, time[timeIndex], time[timeIndex + 1],
-						thrust[timeIndex], thrust[timeIndex + 1]);
-				stepThrust += (thrust[timeIndex] + instThrust) / 2 *
-						(nextTime - time[timeIndex]);
-			} else {
-				// Thrust ended during this step
-				instThrust = 0;
-			}
-			
-			stepThrust /= (nextTime - prevTime);
-			
-		}
-		
-		// Compute average and instantaneous CG (simple average between points)
-		Coordinate nextCG;
-		if (timeIndex < time.length - 1) {
-			nextCG = MathUtil.map(nextTime, time[timeIndex], time[timeIndex + 1],
-					cg[timeIndex], cg[timeIndex + 1]);
-		} else {
-			nextCG = cg[cg.length - 1];
-		}
-		stepCG = instCG.add(nextCG).multiply(0.5);
-		instCG = nextCG;
-		
-		// Update time
-		prevTime = nextTime;
-	}
-	
-	public void reset(){
-		timeIndex = 0;
-		prevTime = 0;
-		instThrust = 0;
-		stepThrust = 0;
-		instCG = motor.getLaunchCG();
-		stepCG = instCG;
-	}
-	
-	@Override
-	public String toString(){
-		return this.motor.getDesignation();
-	}
-	
-}

core/src/net/sf/openrocket/rocketcomponent/FlightConfiguration.java

@@ -528,12 +528,11 @@ public class FlightConfiguration implements FlightConfigurableParameter<FlightCo
 		StringBuilder buf = new StringBuilder();
 		buf.append(String.format("\nDumping %2d Motors for configuration %s: (#: %s)\n", this.motors.size(), this, this.instanceNumber));
 		final String fmt = "    ..[%-8s] <%6s>    %-12s %-20s\n";
-		buf.append(String.format(fmt, "Motor Id", "?active", "Mtr Desig","Mount"));
+		buf.append(String.format(fmt, "Motor Id", "Mtr Desig","Mount"));
 		for( MotorConfiguration curConfig : this.motors.values() ){
 			MotorMount mount = curConfig.getMount();
 			
 			String motorId = curConfig.getID().toShortKey();
-			String activeDescr = (curConfig.isActive()? "active": "inactv");
 			String motorDesig;
 			if( curConfig.isEmpty() ){
 				motorDesig = "(empty)";
@@ -542,7 +541,7 @@ public class FlightConfiguration implements FlightConfigurableParameter<FlightCo
 			}
 			String mountName = ((RocketComponent)mount).getName();
 			
-			buf.append(String.format( fmt, motorId, activeDescr, motorDesig, mountName));
+			buf.append(String.format( fmt, motorId, motorDesig, mountName));
 		}
 		buf.append("\n");
 		return buf.toString();

core/src/net/sf/openrocket/simulation/AbstractSimulationStepper.java

@@ -170,19 +170,13 @@ public abstract class AbstractSimulationStepper implements SimulationStepper {
 		
 		thrust = 0;
 		final double currentTime = status.getSimulationTime() + timestep;
-		Collection<MotorState> activeMotorList = status.getActiveMotors();
-		for (MotorState currentMotorInstance : activeMotorList ) {
+		Collection<MotorSimulation> activeMotorList = status.getMotors();
+		for (MotorSimulation currentMotorState : activeMotorList ) {
 			if ( !stepMotors ) {
-				currentMotorInstance = currentMotorInstance.clone();
-			}
-			// old: transplanted from MotorInstanceConfiguration
-			double instanceTime = currentTime - currentMotorInstance.getIgnitionTime();
-			if (instanceTime >= 0) {
-					currentMotorInstance.step(instanceTime, acceleration, atmosphericConditions);
+				currentMotorState = currentMotorState.clone();
 			}
 			
-			// old: from here
-			thrust += currentMotorInstance.getThrust();
+			thrust += currentMotorState.getThrust( currentTime, atmosphericConditions );
 		}
 		
 		// Post-listeners

core/src/net/sf/openrocket/simulation/BasicEventSimulationEngine.java

@@ -194,11 +194,19 @@ public class BasicEventSimulationEngine implements SimulationEngine {
 				
 				
 				// Check for burnt out motors
-				for( MotorState motor : currentStatus.getAllMotors()){
-					MotorInstanceId motorId = motor.getID();
-					if (!motor.isActive() && currentStatus.addBurntOutMotor(motorId)) {
+				for( MotorSimulation state : currentStatus.getAllMotors()){
+					
+					state.isFinishedThrusting( );
+							
+					MotorInstanceId motorId = state.getID();
+					
+					if ( state.isFinishedThrusting()){
+						// TODO : implement me! 
+						//currentStatus.moveBurntOutMotor( motorId);
+						currentStatus.addBurntOutMotor(motorId);
+					
 						addEvent(new FlightEvent(FlightEvent.Type.BURNOUT, currentStatus.getSimulationTime(),
-								(RocketComponent) motor.getMount(), motorId));
+								(RocketComponent) state.getMount(), motorId));
 					}
 				}
 				
@@ -275,7 +283,7 @@ public class BasicEventSimulationEngine implements SimulationEngine {
 			if (event.getType() == FlightEvent.Type.IGNITION) {
 				MotorMount mount = (MotorMount) event.getSource();
 				MotorInstanceId motorId = (MotorInstanceId) event.getData();
-				MotorState instance = currentStatus.getMotor(motorId);
+				MotorSimulation instance = currentStatus.getMotor(motorId);
 				if (!SimulationListenerHelper.fireMotorIgnition(currentStatus, motorId, mount, instance)) {
 					continue;
 				}
@@ -288,7 +296,7 @@ public class BasicEventSimulationEngine implements SimulationEngine {
 			}
 			
 			// Check for motor ignition events, add ignition events to queue
-			for (MotorState inst : currentStatus.getActiveMotors() ){
+			for (MotorSimulation inst : currentStatus.getAllMotors() ){
 				IgnitionEvent ignitionEvent = inst.getIgnitionEvent();
 				MotorMount mount = inst.getMount();
 				RocketComponent component = (RocketComponent) mount;
@@ -296,7 +304,7 @@ public class BasicEventSimulationEngine implements SimulationEngine {
 				if (ignitionEvent.isActivationEvent(event, component)) {
 					double ignitionDelay = inst.getIgnitionDelay();
 					// TODO:  this event seems to get enque'd multiple times -- more than necessary...
-					//System.err.println("Queing ignition of mtr:"+inst.getMotor().getDesignation()+" @"+currentStatus.getSimulationTime());
+					//System.err.println("Queueing ignition of mtr:"+inst.getMotor().getDesignation()+" @"+currentStatus.getSimulationTime());
 					addEvent(new FlightEvent(FlightEvent.Type.IGNITION,
 							currentStatus.getSimulationTime() + ignitionDelay,
 							component, inst.getID() ));
@@ -341,8 +349,8 @@ public class BasicEventSimulationEngine implements SimulationEngine {
 			case IGNITION: {
 				// Ignite the motor
 				MotorInstanceId motorId = (MotorInstanceId) event.getData();
-				MotorState inst = currentStatus.getMotor( motorId);
-				inst.setIgnitionTime(event.getTime());
+				MotorSimulation inst = currentStatus.getMotor( motorId);
+				inst.ignite( event.getTime());
 				//System.err.println("Igniting motor: "+inst.getMotor().getDesignation()+" @"+currentStatus.getSimulationTime());
 				
 				currentStatus.setMotorIgnited(true);
@@ -370,10 +378,11 @@ public class BasicEventSimulationEngine implements SimulationEngine {
 				if (!currentStatus.isLiftoff()) {
 					throw new SimulationLaunchException(trans.get("BasicEventSimulationEngine.error.earlyMotorBurnout"));
 				}
+				
 				// Add ejection charge event
 				MotorInstanceId motorId = (MotorInstanceId) event.getData();
-				MotorState motor = currentStatus.getMotor( motorId);
-				double delay = motor.getEjectionDelay();
+				MotorSimulation state = currentStatus.getMotor( motorId);
+				double delay = state.getEjectionDelay();
 				if (delay != Motor.PLUGGED) {
 					addEvent(new FlightEvent(FlightEvent.Type.EJECTION_CHARGE, currentStatus.getSimulationTime() + delay,
 							event.getSource(), event.getData()));

core/src/net/sf/openrocket/simulation/MotorSimulation.java

@@ -0,0 +1,160 @@
+package net.sf.openrocket.simulation;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import net.sf.openrocket.models.atmosphere.AtmosphericConditions;
+import net.sf.openrocket.motor.Motor;
+import net.sf.openrocket.motor.MotorConfiguration;
+import net.sf.openrocket.motor.MotorInstanceId;
+import net.sf.openrocket.rocketcomponent.IgnitionEvent;
+import net.sf.openrocket.rocketcomponent.MotorMount;
+import net.sf.openrocket.util.BugException;
+
+public class MotorSimulation {
+	
+	private static final Logger log = LoggerFactory.getLogger(MotorSimulation.class);
+	
+	// for reference: set at initialization ONLY.
+	final protected Motor motor;
+	final protected MotorConfiguration config;
+	final protected double thrustDuration; 
+	
+	// for state:
+	protected double ignitionTime = Double.NaN;
+	protected double cutoffTime = Double.NaN;
+	protected double ejectionTime = Double.NaN;
+	protected MotorState currentState = MotorState.PREFLIGHT;
+		
+	public MotorSimulation(final MotorConfiguration _config) {
+		log.debug(" Creating motor instance of " + _config.getDescription());
+		this.config = _config;
+		this.motor = _config.getMotor();
+		thrustDuration = this.motor.getBurnTimeEstimate();
+		
+		this.resetToPreflight();
+	}
+	
+	@Override
+	public MotorSimulation clone() {
+		try {
+			return (MotorSimulation) super.clone();
+		} catch (CloneNotSupportedException e) {
+			throw new BugException("CloneNotSupportedException", e);
+		}
+	}
+
+	
+	public void arm( final double _armTime ){
+		if( MotorState.PREFLIGHT == currentState ){
+			log.info( "igniting motor: "+this.toString()+" at t="+_armTime);
+			//this.ignitionTime = _ignitionTime;
+			this.currentState = this.currentState.getNext();
+		}else{
+			throw new IllegalStateException("Attempted to arm a motor with status="+this.currentState.getName());
+		}
+	}
+	
+	public boolean isFinishedThrusting(){
+		return currentState.isAfter( MotorState.THRUSTING );
+	}
+	
+	public double getIgnitionTime() {
+		return ignitionTime;
+	}
+
+	public IgnitionEvent getIgnitionEvent() {
+		return config.getIgnitionEvent();
+	}
+
+	
+	public void ignite( final double _ignitionTime ){
+		if( MotorState.ARMED == currentState ){
+			log.info( "igniting motor: "+this.toString()+" at t="+_ignitionTime);
+			this.ignitionTime = _ignitionTime;
+			this.currentState = this.currentState.getNext();
+		}else{
+			throw new IllegalStateException("Attempted to ignite a motor state with status="+this.currentState.getName());
+		}		
+	}
+
+	public void burnOut( final double _burnOutTime ){
+		if( MotorState.THRUSTING == currentState ){
+			log.info( "igniting motor: "+this.toString()+" at t="+_burnOutTime);
+			this.ignitionTime = _burnOutTime;
+			this.currentState = this.currentState.getNext();
+		}else{
+			throw new IllegalStateException("Attempted to stop thrust (burn-out) a motor state with status="+this.currentState.getName());
+		}		
+	}
+	
+	public void fireEjectionCharge( final double _ejectionTime ){
+		if( MotorState.DELAYING == currentState ){
+			log.info( "igniting motor: "+this.toString()+" at t="+_ejectionTime);
+			this.ejectionTime = _ejectionTime;
+			this.currentState = this.currentState.getNext();
+		}else{
+			throw new IllegalStateException("Attempted to fire an ejection charge in motor state: "+this.currentState.getName());
+		}		
+	}
+
+	/* 
+	 * Alias for "burnOut(double)"
+	 */
+	public void cutOff( final double _cutoffTime ){
+		burnOut( _cutoffTime );		
+	}
+
+	public double getIgnitionDelay() {
+		return config.getEjectionDelay();
+	}
+	
+	public double getEjectionDelay() {
+		return config.getEjectionDelay();
+	}
+	
+	public MotorInstanceId getID() {
+		return config.getID();
+	}
+
+	public double getPropellantMass(){
+		return (motor.getLaunchMass() - motor.getBurnoutMass());
+	}
+	
+//	public boolean isActive( ) {
+//		return this.currentState.isActive();
+//	}
+	
+	public MotorMount getMount(){
+		return config.getMount();
+	}
+	
+	public Motor getMotor(){
+		return this.motor;
+	}
+	
+	double getCutOffTime(){
+		return this.cutoffTime;
+	}
+	
+	public double getThrust( final double simTime, final AtmosphericConditions cond){
+		if( this.currentState.isThrusting() ){
+			return motor.getThrustAtMotorTime( simTime - this.getIgnitionTime());
+		}else{
+			return 0.0;
+		}
+	}
+	
+	public void resetToPreflight(){
+		ignitionTime = Double.NaN;
+		cutoffTime = Double.NaN;
+		ejectionTime = Double.NaN;
+		currentState = MotorState.PREFLIGHT;
+	}
+	
+	@Override
+	public String toString(){
+		return this.motor.getDesignation();
+	}
+	
+}

core/src/net/sf/openrocket/simulation/MotorState.java

@@ -1,34 +1,104 @@
 package net.sf.openrocket.simulation;
 
-import net.sf.openrocket.models.atmosphere.AtmosphericConditions;
-import net.sf.openrocket.motor.MotorInstanceId;
-import net.sf.openrocket.rocketcomponent.IgnitionEvent;
-import net.sf.openrocket.rocketcomponent.MotorMount;
 
-public interface MotorState extends Cloneable {
+public enum MotorState {
+	FINISHED("Finished with sequence.", "Finished Producing thrust.", null)
+	,DELAYING("Delaying", " After Burnout, but before ejection", FINISHED){
+		@Override
+		public boolean needsSimulation(){ return true;}
+	}
+	,THRUSTING("Thrusting", "Currently Producing thrust", DELAYING){
+		@Override   
+		public boolean isThrusting(){ return true; }
+		@Override
+		public boolean needsSimulation(){ return true;}
+	}
+	,ARMED("Armed", "Armed, but not yet lit.", FINISHED)
+	,PREFLIGHT("Pre-Launch", "Safed and inactive, prior to launch.", FINISHED)
+	;
 	
-	public void step(double nextTime, double acceleration, AtmosphericConditions cond);
-	public double getThrust();
-	public boolean isActive();
+	private final static int SEQUENCE_NUMBER_END = 10; // arbitrary number
 	
-	public double getIgnitionTime();
-	public void setIgnitionTime( double ignitionTime );
+	private final String name;
+	private final String description;
+	private final int sequenceNumber; 
+	private final MotorState nextState;
 	
-	public void setMount(MotorMount mount);
-	public MotorMount getMount();
+	MotorState( final String name, final String description, final MotorState _nextState) {
+		this.name = name;
+		this.description = description;
+		if( null == _nextState ){
+			this.sequenceNumber = SEQUENCE_NUMBER_END;
+			this.nextState = null;
+		}else{
+			this.sequenceNumber = -1 + _nextState.getSequenceNumber() ;
+			this.nextState = _nextState;
+		}
+	}
 
-	public void setId(MotorInstanceId id);
-	public MotorInstanceId getID();
+	/**
+	 * Return a short name of this motor type.
+	 * @return  a short name of the motor type.
+	 */
+	public String getName() {
+		return this.name;
+	}
 	
-	public IgnitionEvent getIgnitionEvent();
-	public void setIgnitionEvent( IgnitionEvent event );
 
-	public double getIgnitionDelay();
-	public void setIgnitionDelay( double delay );
+	/* 
+	 * 
+	 * @Return a MotorState enum telling what state should follow this one.
+	 */
+	public MotorState getNext( ){
+		return this.nextState;
+	}
 	
-	public double getEjectionDelay();
-	public void setEjectionDelay( double delay);
+	/**
+	 * Return a long description of this motor type.
+	 * @return  a description of the motor type.
+	 */
+	public String getDescription() {
+		return this.description;
+	}
 	
-	public MotorState clone();
+	/** 
+	 * Sequence numbers have no intrinsic meaning, but their sequence (and relative value) 
+	 * indicate which states occur before other states.
+	 * @see isAfter(MotorState)
+	 * @see isBefore(MotorState)
+	 * @return integer indicating this state's place in the allowable sequence
+	 */
+	public int getSequenceNumber(){
+		return this.sequenceNumber;
+	}
 
+	public boolean isAfter( final MotorState other ){
+		return this.getSequenceNumber() > other.getSequenceNumber();
+	}
+	public boolean isBefore( final MotorState other ){
+		return this.getSequenceNumber() < other.getSequenceNumber();
+	}
+	
+
+	/* 
+	 * If this motor is in a state which produces thrust
+	 */
+	public boolean isThrusting(){
+		return false;
+	}
+	
+	/** 
+	 * This flag determines whether the motor has its state updated, and updates of cg and thrust updated.
+	 * A motor instance will always receive events -- which may affect the simulation yes/no state
+	 *    
+	 * @return should this motor be simulated
+	 */
+	public boolean needsSimulation(){
+		return false;
+	}
+
+	@Override
+	public String toString() {
+		return name;
+	}
 }

core/src/net/sf/openrocket/simulation/SimulationStatus.java

@@ -49,9 +49,9 @@ public class SimulationStatus implements Monitorable {
 	private double effectiveLaunchRodLength;
 	
 	// Set of burnt out motors
-	Set<MotorInstanceId> motorBurntOut = new HashSet<MotorInstanceId>();
+	Set<MotorInstanceId> spentMotors = new HashSet<MotorInstanceId>();
 	
-	List<MotorState> motorState = new ArrayList<MotorState>();
+	List<MotorSimulation> motorStateList = new ArrayList<MotorSimulation>();
 	
 	/** Nanosecond time when the simulation was started. */
 	private long simulationStartWallTime = Long.MIN_VALUE;
@@ -148,11 +148,10 @@ public class SimulationStatus implements Monitorable {
 		this.launchRodCleared = false;
 		this.apogeeReached = false;
 		
-		for( MotorConfiguration motorInstance : this.configuration.getActiveMotors() ) {
-			this.motorState.add( motorInstance.getSimulationState() );
+		for( MotorConfiguration motorConfig : this.configuration.getActiveMotors() ) {
+			this.motorStateList.add( new MotorSimulation( motorConfig) );
 		}
 		this.warnings = new WarningSet();
-		
 	}
 	
 	/**
@@ -185,14 +184,14 @@ public class SimulationStatus implements Monitorable {
 		this.launchRodCleared = orig.launchRodCleared;
 		this.apogeeReached = orig.apogeeReached;
 		this.tumbling = orig.tumbling;
-		this.motorBurntOut = orig.motorBurntOut;
+		this.spentMotors = orig.spentMotors;
 		
 		this.deployedRecoveryDevices.clear();
 		this.deployedRecoveryDevices.addAll(orig.deployedRecoveryDevices);
 		
 		// FIXME - is this right?
-		this.motorState.clear();
-		this.motorState.addAll(orig.motorState);
+		this.motorStateList.clear();
+		this.motorStateList.addAll(orig.motorStateList);
 		
 		this.eventQueue.clear();
 		this.eventQueue.addAll(orig.eventQueue);
@@ -225,20 +224,24 @@ public class SimulationStatus implements Monitorable {
 		this.configuration = configuration;
 	}
 	
-	public Collection<MotorState> getAllMotors() {
-		return motorState;
+	public Collection<MotorSimulation> getMotors() {
+		return motorStateList;
 	}
 	
-	public Collection<MotorState> getActiveMotors() {
-		List<MotorState> activeList = new ArrayList<MotorState>();
-		for( MotorState inst : this.motorState ){
-			if( inst.isActive() ){
-				activeList.add( inst );
-			}
+	public Collection<MotorSimulation> getAllMotors() {
+		return motorStateList;
 	}
 	
-		return activeList;
-	}
+//	public Collection<MotorInstance> getActiveMotors() {
+//		List<MotorInstance> activeList = new ArrayList<MotorInstance>();
+//		for( MotorInstance inst : this.motorStateList ){
+//			if( inst.isActive() ){
+//				activeList.add( inst );
+//			}
+//		}
+//		
+//		return activeList;
+//	}
 	
 	public FlightConfiguration getConfiguration() {
 		return configuration;
@@ -260,8 +263,8 @@ public class SimulationStatus implements Monitorable {
 		return flightData;
 	}
 	
-	public MotorState getMotor( final MotorInstanceId motorId ){
-		for( MotorState state : motorState ) {
+	public MotorSimulation getMotor( final MotorInstanceId motorId ){
+		for( MotorSimulation state : motorStateList ) {
 			if ( motorId.equals(state.getID() )) {
 				return state;
 			}
@@ -310,8 +313,15 @@ public class SimulationStatus implements Monitorable {
 	}
 	
 	
+	public boolean moveBurntOutMotor( final MotorInstanceId motor) {
+		// get motor from normal list
+		// remove motor from 'normal' list
+		// add to spent list
+		return false;
+	}
+	
 	public boolean addBurntOutMotor(MotorInstanceId motor) {
-		return motorBurntOut.add(motor);
+		return spentMotors.add(motor);
 	}
 	
 	

core/src/net/sf/openrocket/simulation/extension/impl/ScriptingSimulationListener.java

@@ -18,7 +18,7 @@ import net.sf.openrocket.rocketcomponent.MotorMount;
 import net.sf.openrocket.rocketcomponent.RecoveryDevice;
 import net.sf.openrocket.simulation.AccelerationData;
 import net.sf.openrocket.simulation.FlightEvent;
-import net.sf.openrocket.simulation.MotorState;
+import net.sf.openrocket.simulation.MotorSimulation;
 import net.sf.openrocket.simulation.SimulationStatus;
 import net.sf.openrocket.simulation.exception.SimulationException;
 import net.sf.openrocket.simulation.exception.SimulationListenerException;
@@ -105,7 +105,7 @@ public class ScriptingSimulationListener implements SimulationListener, Simulati
 	}
 	
 	@Override
-	public boolean motorIgnition(SimulationStatus status, MotorInstanceId motorId, MotorMount mount, MotorState instance) throws SimulationException {
+	public boolean motorIgnition(SimulationStatus status, MotorInstanceId motorId, MotorMount mount, MotorSimulation instance) throws SimulationException {
 		return invoke(Boolean.class, true, "motorIgnition", status, motorId, mount, instance);
 	}
 	

core/src/net/sf/openrocket/simulation/listeners/AbstractSimulationListener.java

@@ -9,7 +9,7 @@ import net.sf.openrocket.rocketcomponent.MotorMount;
 import net.sf.openrocket.rocketcomponent.RecoveryDevice;
 import net.sf.openrocket.simulation.AccelerationData;
 import net.sf.openrocket.simulation.FlightEvent;
-import net.sf.openrocket.simulation.MotorState;
+import net.sf.openrocket.simulation.MotorSimulation;
 import net.sf.openrocket.simulation.SimulationStatus;
 import net.sf.openrocket.simulation.exception.SimulationException;
 import net.sf.openrocket.util.BugException;
@@ -72,7 +72,7 @@ public class AbstractSimulationListener implements SimulationListener, Simulatio
 	}
 	
 	@Override
-	public boolean motorIgnition(SimulationStatus status, MotorInstanceId motorId, MotorMount mount, MotorState instance) throws SimulationException {
+	public boolean motorIgnition(SimulationStatus status, MotorInstanceId motorId, MotorMount mount, MotorSimulation instance) throws SimulationException {
 		return true;
 	}
 	

core/src/net/sf/openrocket/simulation/listeners/SimulationEventListener.java

@@ -4,7 +4,7 @@ import net.sf.openrocket.motor.MotorInstanceId;
 import net.sf.openrocket.rocketcomponent.MotorMount;
 import net.sf.openrocket.rocketcomponent.RecoveryDevice;
 import net.sf.openrocket.simulation.FlightEvent;
-import net.sf.openrocket.simulation.MotorState;
+import net.sf.openrocket.simulation.MotorSimulation;
 import net.sf.openrocket.simulation.SimulationStatus;
 import net.sf.openrocket.simulation.exception.SimulationException;
 
@@ -44,7 +44,7 @@ public interface SimulationEventListener {
 	 * @return			<code>true</code> to ignite the motor, <code>false</code> to abort ignition
 	 */
 	public boolean motorIgnition(SimulationStatus status, MotorInstanceId motorId, MotorMount mount,
-			MotorState instance) throws SimulationException;
+			MotorSimulation instance) throws SimulationException;
 	
 	
 	/**

core/src/net/sf/openrocket/simulation/listeners/SimulationListenerHelper.java

@@ -14,7 +14,7 @@ import net.sf.openrocket.rocketcomponent.MotorMount;
 import net.sf.openrocket.rocketcomponent.RecoveryDevice;
 import net.sf.openrocket.simulation.AccelerationData;
 import net.sf.openrocket.simulation.FlightEvent;
-import net.sf.openrocket.simulation.MotorState;
+import net.sf.openrocket.simulation.MotorSimulation;
 import net.sf.openrocket.simulation.SimulationStatus;
 import net.sf.openrocket.simulation.exception.SimulationException;
 import net.sf.openrocket.util.Coordinate;
@@ -168,7 +168,7 @@ public class SimulationListenerHelper {
 	 * @return	<code>true</code> to handle the event normally, <code>false</code> to skip event.
 	 */
 	public static boolean fireMotorIgnition(SimulationStatus status, MotorInstanceId motorId, MotorMount mount,
-			MotorState instance) throws SimulationException {
+			MotorSimulation instance) throws SimulationException {
 		boolean b;
 		int modID = status.getModID(); // Contains also motor instance
 		

core/src/net/sf/openrocket/simulation/listeners/example/DampingMoment.java

@@ -70,7 +70,7 @@ public class DampingMoment extends AbstractSimulationListener {
 		FlightConfiguration config = status.getConfiguration();
 		for (MotorConfiguration inst : config.getActiveMotors()) {
 			double x_position= inst.getX();
-			double x = x_position + inst.getMotor().getLaunchCG().x;
+			double x = x_position + inst.getMotor().getLaunchCGx();
 			if (x > nozzleDistance) {
 				nozzleDistance = x;
 			}

core/src/net/sf/openrocket/utils/MotorCheck.java

@@ -55,10 +55,10 @@ public class MotorCheck {
 						//						sum += m.getTotalTime();
 						sum += m.getDiameter();
 						sum += m.getLength();
-						sum += m.getEmptyCG().weight;
-						sum += m.getEmptyCG().x;
-						sum += m.getLaunchCG().weight;
-						sum += m.getLaunchCG().x;
+						sum += m.getBurnoutMass();
+						sum += m.getBurnoutCGx();
+						sum += m.getLaunchMass();
+						sum += m.getLaunchCGx();
 						sum += m.getMaxThrustEstimate();
 						if (Double.isInfinite(sum) || Double.isNaN(sum)) {
 							System.out.println("ERROR: Invalid motor values");

core/src/net/sf/openrocket/utils/MotorCompare.java

@@ -211,7 +211,7 @@ public class MotorCompare {
 		min = Double.MAX_VALUE;
 		System.out.printf("Init mass  :");
 		for (Motor m : motors) {
-			double f = m.getLaunchCG().weight;
+			double f = m.getLaunchMass();
 			System.out.printf("\t%.2f", f * 1000);
 			max = Math.max(max, f);
 			min = Math.min(min, f);
@@ -229,7 +229,7 @@ public class MotorCompare {
 		min = Double.MAX_VALUE;
 		System.out.printf("Empty mass :");
 		for (Motor m : motors) {
-			double f = m.getEmptyCG().weight;
+			double f = m.getBurnoutMass();
 			System.out.printf("\t%.2f", f * 1000);
 			max = Math.max(max, f);
 			min = Math.min(min, f);

core/src/net/sf/openrocket/utils/MotorCorrelation.java

@@ -8,10 +8,8 @@ import java.util.List;
 
 import net.sf.openrocket.file.motor.GeneralMotorLoader;
 import net.sf.openrocket.file.motor.MotorLoader;
-import net.sf.openrocket.models.atmosphere.AtmosphericConditions;
 import net.sf.openrocket.motor.Motor;
 import net.sf.openrocket.motor.ThrustCurveMotor;
-import net.sf.openrocket.simulation.MotorState;
 import net.sf.openrocket.util.BugException;
 import net.sf.openrocket.util.MathUtil;
 
@@ -61,29 +59,22 @@ public class MotorCorrelation {
 	 * @return			the scaled cross-correlation of the two thrust curves.
 	 */
 	public static double crossCorrelation(Motor motor1, Motor motor2) {		
-		MotorState m1 = motor1.getNewInstance();
-		MotorState m2 = motor2.getNewInstance();
-		
-		AtmosphericConditions cond = new AtmosphericConditions();
-		
 		double t;
 		double auto1 = 0;
 		double auto2 = 0;
 		double cross = 0;
 		for (t = 0; t < 1000; t += 0.01) {
-			m1.step(t, 0, cond);
-			m2.step(t, 0, cond);
 			
-			double t1 = m1.getThrust();
-			double t2 = m2.getThrust();
+			double thrust1 = motor1.getThrustAtMotorTime( t); 
+			double thrust2 = motor2.getThrustAtMotorTime( t);
 			
-			if (t1 < 0 || t2 < 0) {
-				throw new BugException("Negative thrust, t1=" + t1 + " t2=" + t2);
+			if ( thrust1 < 0 || thrust2 < 0) {
+				throw new BugException("Negative thrust, t1=" + thrust1 + " t2=" + thrust2);
 			}
 			
-			auto1 += t1 * t1;
-			auto2 += t2 * t2;
-			cross += t1 * t2;
+			auto1 += thrust1 * thrust1;
+			auto2 += thrust2 * thrust2;
+			cross += thrust1 * thrust2;
 		}
 		
 		double auto = Math.max(auto1, auto2);

core/test/net/sf/openrocket/masscalc/MassCalculatorTest.java

@@ -304,8 +304,8 @@ public class MassCalculatorTest extends BaseTestCase {
 		
 		double expLaunchMass = 0.0164; // kg
 		double expSpentMass = 0.0131; // kg
-		assertEquals(" Motor Mass "+desig+" is incorrect: ", expLaunchMass, activeMotor.getLaunchCG().weight, EPSILON);
-		assertEquals(" Motor Mass "+desig+" is incorrect: ", expSpentMass, activeMotor.getEmptyCG().weight, EPSILON);
+		assertEquals(" Motor Mass "+desig+" is incorrect: ", expLaunchMass, activeMotor.getLaunchMass(), EPSILON);
+		assertEquals(" Motor Mass "+desig+" is incorrect: ", expSpentMass, activeMotor.getBurnoutMass(), EPSILON);
 		
 		// Validate Booster Launch Mass
 		MassCalculator mc = new MassCalculator();

core/test/net/sf/openrocket/motor/ThrustCurveMotorTest.java

@@ -5,16 +5,13 @@ import static org.junit.Assert.assertEquals;
 import org.junit.Test;
 
 import net.sf.openrocket.util.Coordinate;
-import net.sf.openrocket.util.Inertia;
 
 public class ThrustCurveMotorTest {
 	
-	private final double EPS = 0.000001;
+	// private final double EPSILON = 0.000001;
 
 	private final double radius = 0.025;
 	private final double length = 0.10;
-	private final double longitudinal = Inertia.filledCylinderLongitudinal(radius, length);
-	private final double rotational = Inertia.filledCylinderRotational(radius);
 	
 	private final ThrustCurveMotor motor = 
 		new ThrustCurveMotor(Manufacturer.getManufacturer("foo"),
@@ -40,36 +37,116 @@ public class ThrustCurveMotorTest {
 	}
 
 	@Test
-	public void testInstance() {
-		ThrustCurveMotorState instance = motor.getNewInstance();
-		
-		verify(instance, 0, 0.05, 0.02);
-		instance.step(0.0, 0, null);
-		verify(instance, 0, 0.05, 0.02);
-		instance.step(0.5, 0, null);
-		verify(instance, 0.5, 0.05, 0.02);
-		instance.step(1.5, 0, null);
-		verify(instance, (1.5 + 2.125)/2, 0.05, 0.02);
-		instance.step(2.5, 0, null);
-		verify(instance, (2.125 + 2.875)/2, 0.05, 0.02);
-		instance.step(3.0, 0, null);
-		verify(instance, (2+3.0/4 + 3)/2, 0.05, 0.02);
-		instance.step(3.5, 0, null);
-		verify(instance, (1.5 + 3)/2, 0.045, 0.0225);
-		instance.step(4.5, 0, null);
-		// mass and cg is simply average of the end points
-		verify(instance, 1.5/4, 0.035, 0.0275);
-		instance.step(5.0, 0, null);
-		verify(instance, 0, 0.03, 0.03);
+	public void testTimeIndexingNegative(){
+		// attempt to retrieve for a time before the motor ignites
+		assertEquals( 0.0, motor.getPseudoIndex( -1 ),  0.001 );
 	}
 
-	private void verify(ThrustCurveMotorState instance, double thrust, double mass, double cgx) {
-		assertEquals("Testing thrust", thrust, instance.getThrust(), EPS);
-		assertEquals("Testing mass", mass, instance.getCG().weight, EPS);
-		assertEquals("Testing cg x", cgx, instance.getCG().x, EPS);
-		assertEquals("Testing longitudinal inertia", mass*longitudinal, instance.getLongitudinalInertia(), EPS);
-		assertEquals("Testing rotational inertia", mass*rotational, instance.getRotationalInertia(), EPS);
+	@Test
+	public void testTimeRetrieval(){
+		// attempt to retrieve an integer index: 
+		assertEquals( 0.0, motor.getMotorTimeAtIndex( 0 ),  0.001 );
+		assertEquals( 1.0, motor.getMotorTimeAtIndex( 1 ),  0.001 );
+		assertEquals( 4.0, motor.getMotorTimeAtIndex( 3 ),  0.001 );
+
+		final double searchTime = 0.2;
+		assertEquals( searchTime, motor.getMotorTimeAtIndex( motor.getPseudoIndex(searchTime)),  0.001 );	
 	}
 	
+	@Test
+	public void testThrustRetrieval(){
+		// attempt to retrieve an integer index: 
+		assertEquals( 2.0, motor.getThrustAtIndex( 1 ),  0.001 );
+		assertEquals( 3.0, motor.getThrustAtIndex( 2 ),  0.001 );
+		assertEquals( 0.0, motor.getThrustAtIndex( 3 ),  0.001 );
+	}
+	
+	// using better interface
+//	@Test
+//	public void testCGRetrievalByDouble(){
+//		final double actCGx0 = motor.getCGxAtIndex( 0.0 );
+//		assertEquals( 0.02, actCGx0,  0.001 );
+//		final double actMass0 = motor.getMassAtIndex( 0.0 );
+//		assertEquals( 0.05, actMass0,  0.001 );
+//		 
+//		final double actCGx25 = motor.getCGxAtIndex( 2.5 );
+//		assertEquals( 0.025, actCGx25,  0.001 );
+//		final double actMass25 = motor.getMassAtIndex( 2.5 );
+//		assertEquals( 0.04, actMass25,  0.001 );
+//	}
+	
+	// deprecated version. 
+	// delete this method upon change to new function signatures
+	@Test
+	public void testCGRetrieval(){
+		final double actCGx0 = motor.getCGAtIndex( 0.0 ).x;
+		assertEquals( 0.02, actCGx0,  0.001 );
+		final double actMass0 = motor.getCGAtIndex( 0.0 ).weight;
+		assertEquals( 0.05, actMass0,  0.001 );
+		 
+		final double actCGx25 = motor.getCGAtIndex( 2.5 ).x;
+		assertEquals( 0.025, actCGx25,  0.001 );
+		final double actMass25 = motor.getCGAtIndex( 2.5 ).weight;
+		assertEquals( 0.04, actMass25,  0.001 );
+	}
+	
+	@Test
+	public void testTimeIndexingPastEnd(){
+		// attempt to retrieve for a time after motor cutoff
+		assertEquals( 3.0, motor.getPseudoIndex( 5.0),  0.001 );
+	}
+	@Test
+	public void testTimeIndexingAtEnd(){
+		// attempt to retrieve for a time just at motor cutoff
+		assertEquals( 3.0, motor.getPseudoIndex( 4.0),  0.001 );
+	}
+	@Test
+	public void testTimeIndexingDuring(){
+		// attempt to retrieve for a generic time during the motor's burn
+		assertEquals( 1.6, motor.getPseudoIndex( 2.2), 0.001 );
+	}
+	@Test
+	public void testTimeIndexingSnapUp(){
+		// attempt to retrieve for a generic time during the motor's burn
+		assertEquals( 3.0, motor.getPseudoIndex( 3.9999), 0.001 );
+	}
+	@Test
+	public void testTimeIndexingSnapDown(){
+		// attempt to retrieve for a generic time during the motor's burn
+		assertEquals( 2.0, motor.getPseudoIndex( 3.0001), 0.001 );
+	}
+	
+//	@Test
+//	public void testInstance() {
+//		ThrustCurveMotorState instance = motor.getNewInstance();
+//		
+//		verify(instance, 0, 0.05, 0.02);
+//		instance.step(0.0, null);
+//		verify(instance, 0, 0.05, 0.02);
+//		instance.step(0.5, null);
+//		verify(instance, 0.5, 0.05, 0.02);
+//		instance.step(1.5, null);
+//		verify(instance, (1.5 + 2.125)/2, 0.05, 0.02);
+//		instance.step(2.5, null);
+//		verify(instance, (2.125 + 2.875)/2, 0.05, 0.02);
+//		instance.step(3.0, null);
+//		verify(instance, (2+3.0/4 + 3)/2, 0.05, 0.02);
+//		instance.step(3.5, null);
+//		verify(instance, (1.5 + 3)/2, 0.045, 0.0225);
+//		instance.step(4.5, null);
+//		// mass and cg is simply average of the end points
+//		verify(instance, 1.5/4, 0.035, 0.0275);
+//		instance.step(5.0, null);
+//		verify(instance, 0, 0.03, 0.03);
+//	}
+//	
+//	private void verify(ThrustCurveMotorState instance, double thrust, double mass, double cgx) {
+//		assertEquals("Testing thrust", thrust, instance.getThrust(), EPS);
+//		assertEquals("Testing mass", mass, instance.getCG().weight, EPS);
+//		assertEquals("Testing cg x", cgx, instance.getCG().x, EPS);
+//		assertEquals("Testing longitudinal inertia", mass*longitudinal, instance.getMotor().getLongitudinalInertia(), EPS);
+//		assertEquals("Testing rotational inertia", mass*rotational, instance.getMotor().getRotationalInertia(), EPS);
+//	}
+			
 	
 }

swing/src/net/sf/openrocket/database/MotorDatabaseLoader.java

@@ -8,6 +8,9 @@ import java.io.InputStream;
 import java.io.ObjectInputStream;
 import java.util.List;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import net.sf.openrocket.database.motor.ThrustCurveMotorSetDatabase;
 import net.sf.openrocket.file.iterator.DirectoryIterator;
 import net.sf.openrocket.file.iterator.FileIterator;
@@ -20,9 +23,6 @@ import net.sf.openrocket.startup.Application;
 import net.sf.openrocket.util.BugException;
 import net.sf.openrocket.util.Pair;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 /**
  * An asynchronous database loader that loads the internal thrust curves
  * and external user-supplied thrust curves to a ThrustCurveMotorSetDatabase.

swing/src/net/sf/openrocket/gui/dialogs/motor/MotorChooserDialog.java

@@ -21,10 +21,9 @@ import net.sf.openrocket.rocketcomponent.FlightConfigurationId;
 import net.sf.openrocket.rocketcomponent.MotorMount;
 import net.sf.openrocket.startup.Application;
 
+@SuppressWarnings("serial")
 public class MotorChooserDialog extends JDialog implements CloseableDialog {
 
-	private static final long serialVersionUID = 6903386330489783515L;
-
 	private final ThrustCurveMotorSelectionPanel selectionPanel;
 	
 	private boolean okClicked = false;

swing/src/net/sf/openrocket/gui/dialogs/motor/thrustcurve/MotorInformationPanel.java

@@ -16,14 +16,6 @@ import javax.swing.JScrollPane;
 import javax.swing.JTextArea;
 import javax.swing.SwingUtilities;
 
-import net.miginfocom.swing.MigLayout;
-import net.sf.openrocket.gui.util.GUIUtil;
-import net.sf.openrocket.gui.util.Icons;
-import net.sf.openrocket.l10n.Translator;
-import net.sf.openrocket.motor.ThrustCurveMotor;
-import net.sf.openrocket.startup.Application;
-import net.sf.openrocket.unit.UnitGroup;
-
 import org.jfree.chart.ChartFactory;
 import org.jfree.chart.ChartPanel;
 import org.jfree.chart.JFreeChart;
@@ -34,6 +26,14 @@ import org.jfree.chart.title.TextTitle;
 import org.jfree.data.xy.XYSeries;
 import org.jfree.data.xy.XYSeriesCollection;
 
+import net.miginfocom.swing.MigLayout;
+import net.sf.openrocket.gui.util.GUIUtil;
+import net.sf.openrocket.gui.util.Icons;
+import net.sf.openrocket.l10n.Translator;
+import net.sf.openrocket.motor.ThrustCurveMotor;
+import net.sf.openrocket.startup.Application;
+import net.sf.openrocket.unit.UnitGroup;
+
 @SuppressWarnings("serial")
 class MotorInformationPanel extends JPanel {
 	
@@ -246,9 +246,9 @@ class MotorInformationPanel extends JPanel {
 		burnTimeLabel.setText(UnitGroup.UNITS_SHORT_TIME.getDefaultUnit().toStringUnit(
 				selectedMotor.getBurnTimeEstimate()));
 		launchMassLabel.setText(UnitGroup.UNITS_MASS.getDefaultUnit().toStringUnit(
-				selectedMotor.getLaunchCG().weight));
+				selectedMotor.getLaunchMass()));
 		emptyMassLabel.setText(UnitGroup.UNITS_MASS.getDefaultUnit().toStringUnit(
-				selectedMotor.getEmptyCG().weight));
+				selectedMotor.getBurnoutMass()));
 		dataPointsLabel.setText("" + (selectedMotor.getTimePoints().length - 1));
 		if (digestLabel != null) {
 			digestLabel.setText(selectedMotor.getDigest());

swing/src/net/sf/openrocket/gui/dialogs/motor/thrustcurve/ThrustCurveMotorColumns.java

@@ -151,11 +151,11 @@ enum ThrustCurveMotorColumns {
 				UnitGroup.UNITS_IMPULSE.getDefaultUnit()
 						.toStringUnit(m.getTotalImpulseEstimate()) + "<br>");
 		tip += (trans.get("TCurveMotor.ttip.launchMass") + " " +
-				UnitGroup.UNITS_MASS.getDefaultUnit().toStringUnit(m.getLaunchCG().weight) +
+				UnitGroup.UNITS_MASS.getDefaultUnit().toStringUnit(m.getLaunchMass()) +
 				"<br>");
 		tip += (trans.get("TCurveMotor.ttip.emptyMass") + " " +
 				UnitGroup.UNITS_MASS.getDefaultUnit()
-						.toStringUnit(m.getEmptyCG().weight));
+						.toStringUnit(m.getBurnoutMass()));
 		return tip;
 	}
 	

swing/src/net/sf/openrocket/gui/print/DesignReport.java

@@ -388,7 +388,7 @@ public class DesignReport {
 					motorTable.addCell(ITextHelper.createCell(
 							ttwFormat.format(ttw) + ":1", border));
 					
-					double propMass = (motor.getLaunchCG().weight - motor.getEmptyCG().weight);
+					double propMass = (motor.getLaunchMass() - motor.getBurnoutMass());
 					motorTable.addCell(ITextHelper.createCell(
 							UnitGroup.UNITS_MASS.getDefaultUnit().toStringUnit(propMass), border));