DeadReckoning/DRValue.cpp at master · Andos/DeadReckoning · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
#include "DRValue.h"

void DeadReckoningValue::Reset()
{
	currentPos = stepPos = posAtUpdate = prevPos = oldPos = oldSpeed = nextPos = averageUpdateInterval = 0;
	lastUpdate = currentStep = timeDeltaIndex = numDeltas = 0;
	smoothing = speedOverride = 0;
	extrapolationMode = 0;
	doSpeedOverride = false;
	useAcceleration = false;
	wrapMode = WRAP_LINEAR;
	wrapValue = 0;
	for(int i=0; i<AVERAGEWINDOW; i++)
		timeDeltas[i]=0;
}

void DeadReckoningValue::UpdateValue(float newValue, long time)
{
	float speed;
	long timeDelta = time - lastUpdate;
	if(timeDelta == 0)
		return;

	//If the value is circular, map it down into a linear value
	if(wrapMode == WRAP_CIRCULAR)
	{
		diffAtUpdate = CircularDifference(newValue, oldPos, wrapValue);
		newValue = oldPos + diffAtUpdate;
	}
	else
		diffAtUpdate = newValue-oldPos;

	UpdateAverageInterval(timeDelta);

	if(!doSpeedOverride)
		speed = diffAtUpdate/timeDelta;
	else
	{
		speed = oldSpeed = speedOverride;
		doSpeedOverride = false;
	}

	//If the object changes direction
	if((speed>0 && oldSpeed<0) || (speed<0 && oldSpeed>0))
		oldSpeed = 0;

	if(useAcceleration)
	{
		float acceleration = speed - oldSpeed;

		float increaseFactor = 1.0f;
		//The increasefactor can kinda be seen as the acceleration of the acceleration.
		if(oldSpeed != 0)
			increaseFactor = CLAMP(speed/oldSpeed, 0.0f, 1.0f);
		else
			increaseFactor = 0;

		//Predict the next position
		nextPos = newValue + (speed + acceleration*increaseFactor) * averageUpdateInterval;
	}
	else
		nextPos = newValue + speed * averageUpdateInterval;

	//Store values for next update
	currentStep = 0;

	prevPos = oldPos;
	oldPos = newValue;

	lastUpdate = time;
	oldSpeed = speed;
	posAtUpdate = currentPos;
	timeDeltaIndex = (timeDeltaIndex+1) % AVERAGEWINDOW;
}

void DeadReckoningValue::SetValue(float value)
{
	currentPos = prevPos = posAtUpdate = stepPos = nextPos = oldPos = value;
}

void DeadReckoningValue::SetSpeed(float speed)
{
	//Recalculate movement
	doSpeedOverride = true;
	speedOverride = speed;
	oldPos = currentPos;
	nextPos = currentPos + speed * averageUpdateInterval;
}

void DeadReckoningValue::DoStep()
{
	long timespan = (long)averageUpdateInterval;
	if(currentStep >= timespan)
		return;

	currentStep++;

	float mu = 1.0f/averageUpdateInterval * currentStep;
	float secondGuess = nextPos + (nextPos-oldPos);

	switch(extrapolationMode)
	{
	case INTERPOLATION_CUBIC:
		stepPos = CubicInterpolation(prevPos, posAtUpdate, nextPos, secondGuess, mu);
		break;
	case INTERPOLATION_LINEAR:
		stepPos = posAtUpdate+(nextPos-posAtUpdate)*mu;
		break;
	}

	//Movement smoothing
	if(smoothing > 1)
		currentPos = currentPos + (stepPos-currentPos)/smoothing;
	else
		currentPos = stepPos;
}

float DeadReckoningValue::CubicInterpolation(float y0, float y1, float y2, float y3, float mu)
{
	float a0,a1,a2,a3,mu2;
	mu2 = mu*mu;
	a0 = y3 - y2 - y0 + y1;
	a1 = y0 - y1 - a0;
	a2 = y2 - y0;
	a3 = y1;
	return a0*mu*mu2+a1*mu2+a2*mu+a3;
}

void DeadReckoningValue::UpdateAverageInterval(long timeDelta)
{
	timeDeltas[timeDeltaIndex] = timeDelta;
	if(numDeltas < AVERAGEWINDOW)
		numDeltas++;

	averageUpdateInterval = 0;
	int maxLoop = MIN(AVERAGEWINDOW, numDeltas);
	for(int i=0; i<maxLoop; i++)
		averageUpdateInterval += timeDeltas[i];
	averageUpdateInterval /= maxLoop;
}

float DeadReckoningValue::CircularDifference(float angleA, float angleB, float wrapValue)
{
	float ret = fmod(angleA - angleB, wrapValue);
	float halfWrap = wrapValue / 2.0f;

	if(ret >= halfWrap)
		return ret-wrapValue;
	else if(ret < -halfWrap)
		return ret+wrapValue;
	else
		return ret;
}


void DRObj::Reset()
{
	fixedValue = 0;
	previousAngle = 0.0f;
	oldX = oldY = 0;
	xPosition.Reset();
	yPosition.Reset();
	direction.Reset();
	angle.Reset();
}