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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
|
/// <reference path="../../scripts/jquery-3.5.1.min.js"/>
/// <reference path="../../_shared/math/vec2.js" />
/// <reference path="../../_shared/math/mat4.js" />
/// <reference path="../../_shared/2d/shader.js" />
/// <reference path="../../_shared/math/circle.js" />
/// <reference path="../../_shared/2d/program_common.js" />
(function() {
function main() {
// Define Constants
const CIRCLE_RADIUS = 16;
const GRAVITY = 9.8;
const COF_OF_RESTITUITION = 0.7;
// Retrieve context
const lProgramContext = getContext('#rigidbody_3a');
if (lProgramContext.gl === null) {
console.error('Unable to initialize WebGL. Your browser or machine may not support it.');
return;
}
lProgramContext.gl.clearColor(0.0, 0.0, 0.0, 1.0);
lProgramContext.gl.clear(lProgramContext.gl.COLOR_BUFFER_BIT);
function run() {
console.log('Running Rigid Body 3a');
lProgramContext.load().then(function(pProgramInfo) {
// Circile initialization
const horizontalCircle = circle(lProgramContext.gl, CIRCLE_RADIUS, 30, [
{ x: 1, y: 1, z: 0, w: 1 },
{ x: 1, y: 0, z: 1, w: 1 },
{ x: 0, y: 1, z: 1, w: 1 },
{ x: 0, y: 1, z: 0, w: 1 }
], vec2(400, lProgramContext.height / 2.0));
const verticalCircle = circle(lProgramContext.gl, CIRCLE_RADIUS, 30, [
{ x: 1, y: 0, z: 0, w: 1 },
{ x: 0, y: 1, z: 0, w: 1 },
{ x: 0, y: 0, z: 1, w: 1 }
], vec2(lProgramContext.width / 2.0, lProgramContext.height / 2.0 + 100));
horizontalCircle.velocity = vec2(-100, 0);
verticalCircle.velocity = vec2(0, -100);
lTimeStepScale = $('#time_step_slider').val();
/**
* Run the update method of a single circle
*
* @param {circle} pCircle
* @param {number} pDeltaTimeSeconds
*/
function updateCircle(pCircle, pDeltaTimeSeconds) {
// Same physics updates from part 1
applyForce(pCircle, vec2(0, -1.0 * (pCircle.mass * GRAVITY)));
const lCurrentAcceleration = scaleVec2(pCircle.force, 1.0 / pCircle.mass);
pCircle.prevVelocity = pCircle.velocity;
pCircle.velocity = addVec2(pCircle.velocity, scaleVec2(lCurrentAcceleration, pDeltaTimeSeconds));
pCircle.prevPos = { ...pCircle.position };
pCircle.position = addVec2(pCircle.position, scaleVec2(pCircle.velocity, pDeltaTimeSeconds));
pCircle.force = vec2();
// Same physics updates from part 2
const lMomentOfInertia = getMomentOfInertia(pCircle);
const lAngularAcceleration = pCircle.torque / lMomentOfInertia;
pCircle.rotationVelocity += lAngularAcceleration * pDeltaTimeSeconds;
pCircle.rotationRadians += pCircle.rotationVelocity * pDeltaTimeSeconds;
pCircle.torque = 0;
pCircle.model = rotateMatrix2d(translateMatrix(mat4(), pCircle.position.x, pCircle.position.y, 0), pCircle.rotationRadians);
}
function update(pDeltaTimeSeconds) {
pDeltaTimeSeconds = pDeltaTimeSeconds * lTimeStepScale;
updateCircle(horizontalCircle, pDeltaTimeSeconds);
updateCircle(verticalCircle, pDeltaTimeSeconds);
collision(pDeltaTimeSeconds);
render();
}
function collision(pDeltaTimeSeconds) {
if (!doCirclesIntersect(horizontalCircle, verticalCircle)) {
return false;
}
// We have an intersection! Let's try and figure out precisely when that happened.
let lSubdividedDeltaTime = pDeltaTimeSeconds;
let lSubdivideHorizontalBall = undefined,
lSubdivideVerticalBall = undefined;
do {
lSubdivideHorizontalBall = JSON.parse(JSON.stringify(horizontalCircle));
lSubdivideHorizontalBall.position = {...horizontalCircle.prevPos};
lSubdivideHorizontalBall.velocity = {...horizontalCircle.prevVelocity};
lSubdivideVerticalBall = JSON.parse(JSON.stringify(verticalCircle));
lSubdivideVerticalBall.position = {...verticalCircle.prevPos};
lSubdivideVerticalBall.velocity = {...verticalCircle.prevVelocity};
lSubdividedDeltaTime = lSubdividedDeltaTime / 2.0;
updateCircle(lSubdivideHorizontalBall, lSubdividedDeltaTime);
updateCircle(lSubdivideVerticalBall, lSubdividedDeltaTime);
if (lSubdividedDeltaTime === 0) {
console.error('This should NOT be happening');
break;
}
} while (doCirclesIntersect(lSubdivideHorizontalBall, lSubdivideVerticalBall))
const lIntersectionResult = getIntersectionDataForCircles(lSubdivideHorizontalBall, lSubdivideVerticalBall);
console.log('We have a collision');
const lRelativeVelocity = lIntersectionResult.relativeVelocity,
lCollisionNormal = lIntersectionResult.collisionNormal,
lFirstPerp = getPerp2(lIntersectionResult.firstPointOfApplication),
lSecondPerp = getPerp2(lIntersectionResult.secondPointOfApplication);
const lNumerator = dot2(scaleVec2(lRelativeVelocity, -(1.0 + COF_OF_RESTITUITION)), lCollisionNormal);
const lLinearDenomPart = dot2(lCollisionNormal, (scaleVec2(lCollisionNormal, 1 / horizontalCircle.mass + 1 / verticalCircle.mass)));
const lRotationalDenomPart = (Math.pow(dot2(lFirstPerp, lCollisionNormal), 2) / getMomentOfInertia(horizontalCircle))
+ (Math.pow(dot2(lSecondPerp, lCollisionNormal), 2) / getMomentOfInertia(verticalCircle))
const lImpulseMagnitude = lNumerator / (lLinearDenomPart + lRotationalDenomPart);
horizontalCircle.position = lSubdivideHorizontalBall.position;
verticalCircle.position = lSubdivideVerticalBall.position;
horizontalCircle.velocity = addVec2(horizontalCircle.velocity, scaleVec2(lCollisionNormal, lImpulseMagnitude / horizontalCircle.mass));
verticalCircle.velocity = subVec2(verticalCircle.velocity, scaleVec2(lCollisionNormal, lImpulseMagnitude / verticalCircle.mass));
horizontalCircle.rotationVelocity = horizontalCircle.rotationVelocity + dot2(lFirstPerp, scaleVec2(lCollisionNormal, lImpulseMagnitude)) / getMomentOfInertia(horizontalCircle);
verticalCircle.rotationVelocity = verticalCircle.rotationVelocity - dot2(lSecondPerp, scaleVec2(lCollisionNormal, lImpulseMagnitude)) / getMomentOfInertia(verticalCircle);
updateCircle(horizontalCircle, pDeltaTimeSeconds - lSubdividedDeltaTime);
updateCircle(verticalCircle, pDeltaTimeSeconds - lSubdividedDeltaTime);
return true;
}
function render() {
lProgramContext.gl.clearColor(0.0, 0.0, 0.0, 1.0);
lProgramContext.gl.clearDepth(1.0);
lProgramContext.gl.enable(lProgramContext.gl.DEPTH_TEST);
lProgramContext.gl.depthFunc(lProgramContext.gl.LEQUAL);
lProgramContext.gl.clear(lProgramContext.gl.COLOR_BUFFER_BIT | lProgramContext.gl.DEPTH_BUFFER_BIT);
lProgramContext.gl.useProgram(pProgramInfo.program);
lProgramContext.gl.uniformMatrix4fv(pProgramInfo.uniformLocations.projection, false, lProgramContext.perspective);
renderCircle(lProgramContext.gl, pProgramInfo, horizontalCircle);
renderCircle(lProgramContext.gl, pProgramInfo, verticalCircle);
}
const TORQUE_MULTIPLIER = 100.0; // TODO: This may be unncessary
function applyForce(pCircle, pForceVector, pPointOfApplication) {
if (pPointOfApplication !== undefined) {
const lOriginToPointOfApp = subVec2(vec2(), pPointOfApplication),
lPerpVec = vec2(-lOriginToPointOfApp.y, lOriginToPointOfApp.x);
pCircle.torque += TORQUE_MULTIPLIER * dot2(lPerpVec, pForceVector);
}
pCircle.force = addVec2(pCircle.force, pForceVector);
}
function cleanup() {
lProgramContext.gl.deleteBuffer(horizontalCircle.buffer);
lProgramContext.gl.deleteBuffer(verticalCircle.buffer);
lProgramContext.gl.deleteProgram(pProgramInfo.program);
lProgramContext.gl.clearColor(0.0, 0.0, 0.0, 1.0);
lProgramContext.gl.clear(lProgramContext.gl.COLOR_BUFFER_BIT);
}
function reset() {
lExitRequestFunc();
lProgramContext.reset();
$('#time_step_slider').unbind('change');
}
const lExitRequestFunc = requestUpdateLoop(update, cleanup);
lProgramContext.stopButton.on('click', reset);
$('#time_step_slider').on('change', function() { lTimeStepScale = $(this).val(); });
});
}
lProgramContext.playButton.on('click', run);
}
$(document).ready(main);
})()
|
