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Diffstat (limited to 'frontend/2d/_rigidbody/rigidbody_3a.js')
| -rw-r--r-- | frontend/2d/_rigidbody/rigidbody_3a.js | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/frontend/2d/_rigidbody/rigidbody_3a.js b/frontend/2d/_rigidbody/rigidbody_3a.js new file mode 100644 index 0000000..d38f1da --- /dev/null +++ b/frontend/2d/_rigidbody/rigidbody_3a.js @@ -0,0 +1,190 @@ +/// <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); +})()
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