Instance Methods
(void)	- saveToLastFrame

(Frame)	- frameAtTime:fromFrame:

Detailed Description

Definition at line 51 of file OOExhaustPlumeEntity.m.

Method Documentation

◆ frameAtTime:fromFrame:

- (Frame) frameAtTime:		(double)	t_frame
fromFrame:		(Frame)	frame_zero

Extends class OOExhaustPlumeEntity.

Definition at line 540 of file OOExhaustPlumeEntity.m.

                     :(double)t_frame fromFrame:(Frame) frame_zero  // t_frame is relative to now ie. -0.5 = half a second ago.
{
    if (t_frame >= 0.0)  return frame_zero;
    
    Frame frame_one;
    
    int t1 = PREV(_nextFrame);
    double moment_in_time = frame_zero.timeframe + t_frame;
    double period, f0;
    
    if (moment_in_time > _trackTime)                    // between the last saved frame and now
    {
        frame_one = _track[t1]; // last saved moment
        period = (moment_in_time - t_frame) - _trackTime;
        f0 = 1.0 + t_frame/period;
    }
    else if (moment_in_time < _track[_nextFrame].timeframe) // more than kExhaustFrameCount frames back
    {
        return _track[_nextFrame];
    }
    else
    {
        while (moment_in_time < _track[t1].timeframe)
        {
            t1 = PREV(t1);
        }
        int t0 = NEXT(t1);
        
        frame_zero = _track[t0];
        frame_one = _track[t1];
        period = frame_zero.timeframe - frame_one.timeframe;
        f0 = (moment_in_time - _track[t1].timeframe)/period;
    }
    
    // interpolate
    double f1 = 1.0 - f0;
    
    HPVector posn;
    posn.x =    f0 * frame_zero.position.x + f1 * frame_one.position.x;
    posn.y =    f0 * frame_zero.position.y + f1 * frame_one.position.y;
    posn.z =    f0 * frame_zero.position.z + f1 * frame_one.position.z;
    Quaternion qrot;
    qrot.w =    (float)f0 * frame_zero.orientation.w + (float)f1 * frame_one.orientation.w;
    qrot.x =    (float)f0 * frame_zero.orientation.x + (float)f1 * frame_one.orientation.x;
    qrot.y =    (float)f0 * frame_zero.orientation.y + (float)f1 * frame_one.orientation.y;
    qrot.z =    (float)f0 * frame_zero.orientation.z + (float)f1 * frame_one.orientation.z;
    
    Frame result;
    result.position = posn;
    result.orientation = qrot;
    result.timeframe = moment_in_time;
    result.k = vector_forward_from_quaternion(qrot);
    return result;
}

References Frame::k, NEXT, Frame::orientation, Frame::position, PREV, Frame::timeframe, and vector_forward_from_quaternion().

Referenced by OOExhaustPlumeEntity::update:.

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◆ saveToLastFrame

- (void) saveToLastFrame

Extends class OOExhaustPlumeEntity.

Definition at line 523 of file OOExhaustPlumeEntity.m.

{
    ShipEntity *ship = [self owner];
    
    // Absolute position of self
    // normally this would use the transformation matrix, but that
    // introduces inaccuracies
    // so just use the rotation matrix, then translate using HPVectors
    HPVector framePos = OOHPVectorMultiplyMatrix([self position], [ship drawRotationMatrix]);
    framePos = HPvector_add(framePos,[ship position]);
    Frame frame = { [UNIVERSE getTime], framePos, [ship normalOrientation], [ship upVector] };
    
    _track[_nextFrame] = frame;
    _nextFrame = (_nextFrame + 1) % kExhaustFrameCount;
}

References kExhaustFrameCount, Entity::normalOrientation, OOHPVectorMultiplyMatrix(), Entity::owner, saveToLastFrame, and ShipEntity::upVector.

Referenced by saveToLastFrame, and OOExhaustPlumeEntity::update:.