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const BYTES_PER_FLOAT = 4;
function circle(pGl, pRadius, pSegments, pColorList, pInitialPosition) {
const lBuffer = pGl.createBuffer();
pGl.bindBuffer(pGl.ARRAY_BUFFER, lBuffer);
var lBufferedData = [];
vertexCount = 0;
const lAngleIncrements = (360.0 / pSegments) * (Math.PI / 180.0);
for (let lSegIdx = 0; lSegIdx < pSegments; lSegIdx++) {
const lAngle = lAngleIncrements * lSegIdx,
lNextAngle = lAngleIncrements * (lSegIdx + 1),
lColorIndex = Math.floor(pColorList.length * (lSegIdx / pSegments)),
lColor = pColorList[lColorIndex]; // TODO: Calculate which one to use
lBufferedData = lBufferedData.concat([
0, 0, lColor.x, lColor.y, lColor.z, lColor.w,
pRadius * Math.sin(lAngle), pRadius * Math.cos(lAngle), lColor.x, lColor.y, lColor.z, lColor.w,
pRadius * Math.sin(lNextAngle), pRadius * Math.cos(lNextAngle), lColor.x, lColor.y, lColor.z, lColor.w
]);
vertexCount += 3;
}
pGl.bufferData(pGl.ARRAY_BUFFER, new Float32Array(lBufferedData), pGl.STATIC_DRAW)
pGl.bindBuffer(pGl.ARRAY_BUFFER, undefined);
return {
buffer: lBuffer,
vertexCount: vertexCount,
position: pInitialPosition || vec2(),
velocity: vec2(),
force: vec2(),
mass: 1,
rotationRadians: 0,
model: mat4(),
radius: pRadius
};
}
function renderCircle(pGl, pProgramInfo, pCircle) {
pGl.bindBuffer(pGl.ARRAY_BUFFER, pCircle.buffer);
{
pGl.enableVertexAttribArray(pProgramInfo.attributeLocations.position);
pGl.vertexAttribPointer(pProgramInfo.attributeLocations.position, 2, pGl.FLOAT, false, BYTES_PER_FLOAT * 6, 0);
pGl.enableVertexAttribArray(pProgramInfo.attributeLocations.color);
pGl.vertexAttribPointer(pProgramInfo.attributeLocations.color, 4, pGl.FLOAT, false, BYTES_PER_FLOAT * 6, BYTES_PER_FLOAT * 2);
}
pGl.drawArrays(pGl.TRIANGLE_STRIP, 0, pCircle.vertexCount);
}
function getMomentOfInertia(pCircle) {
return (Math.PI * Math.pow(pCircle.radius, 4)) / 4;
}
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