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webgpufundamentals/webgpu/webgpu-javascript-analogies.html
Gregg Tavares 41a5d5d8d3 edit
2023-07-12 19:29:23 -07:00

367 lines
11 KiB
HTML

<!DOCTYPE html>
<style>
pre { margin: 0; }
</style>
<body></body>
<script type="module">
/* eslint no-unused-vars: 0 */
// Wrap console log so we don't have to explain some `log` function.
console.log = (origFn => {
return function(...args) {
const elem = document.createElement('pre');
elem.textContent = args.join(' ');
document.body.appendChild(elem);
origFn(...args);
};
})(console.log.bind(console));
section('run by count');
{
function draw(count, vertexShaderFn) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
internalBuffer[i] = vertexShaderFn(i);
}
console.log(JSON.stringify(internalBuffer));
}
const shader = v => v * 2;
draw(4, shader);
}
section('uniforms');
{
function draw(count, vertexShaderFn, bindings) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
internalBuffer[i] = vertexShaderFn(i, bindings);
}
console.log(JSON.stringify(internalBuffer));
}
const vertexShader = (v, bindings) => {
const uniforms = bindings[0];
return v * uniforms.multiplier;
};
const uniforms1 = {multiplier: 3};
const uniforms2 = {multiplier: 5};
const bindings1 = [uniforms1];
const bindings2 = [uniforms2];
const count = 4;
draw(count, vertexShader, bindings1);
// outputs [0, 3, 6, 9]
draw(count, vertexShader, bindings2);
// outputs [0, 5, 10, 15]
}
section('attributes');
{
function draw(count, vertexShaderFn, bindings, attribsSpec) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
const attribs = getAttribs(attribsSpec, i);
internalBuffer[i] = vertexShaderFn(i, bindings, attribs);
}
console.log(JSON.stringify(internalBuffer));
}
function getAttribs(attribs, ndx) {
return attribs.map(({source, offset, stride}) => source[ndx * stride + offset]);
}
const buffer1 = [0, 1, 2, 3, 4, 5, 6, 7];
const buffer2 = [11, 22, 33, 44];
const attribsSpec = [
{ source: buffer1, offset: 0, stride: 2, },
{ source: buffer1, offset: 1, stride: 2, },
{ source: buffer2, offset: 0, stride: 1, },
];
const vertexShader = (v, bindings, attribs) => (attribs[0] + attribs[1]) * attribs[2];
const bindings = [];
const count = 4;
draw(count, vertexShader, bindings, attribsSpec);
}
section('buffers');
{
function getAttribs(attribs, ndx) {
return attribs.map(({source, offset, stride}) => source[ndx * stride + offset]);
}
function draw(count, vertexShaderFn, bindings, attribsSpec) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
const attribs = getAttribs(attribsSpec, i);
internalBuffer[i] = vertexShaderFn(i, bindings, attribs);
}
console.log(JSON.stringify(internalBuffer));
}
const buffer1 = [0, 1, 2, 3, 4, 5, 6, 7];
const buffer2 = [11, 22, 33, 44];
const attribsSpec = [];
const bindings = [
buffer1,
buffer2,
];
const vertexShader = (ndx, bindings /* , attribs */) =>
(bindings[0][ndx * 2] + bindings[0][ndx * 2 + 1]) * bindings[1][ndx];
const count = 4;
draw(count, vertexShader, bindings, attribsSpec);
// outputs [11, 110, 297, 572]
}
section('textures');
{
function getAttribs(attribs, ndx) {
return attribs.map(({source, offset, stride}) => source[ndx * stride + offset]);
}
function draw(count, vertexShaderFn, bindings, attribsSpec) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
const attribs = getAttribs(attribsSpec, i);
internalBuffer[i] = vertexShaderFn(i, bindings, attribs);
}
console.log(JSON.stringify(internalBuffer));
}
function textureSample(texture, ndx) {
const startNdx = ndx | 0; // round down to an int
const fraction = ndx % 1; // get the fractional part between indices
const start = texture[startNdx];
const end = texture[startNdx + 1];
return start + (end - start) * fraction; // compute value between start and end
}
const texture = [10, 20, 30, 40, 50, 60, 70, 80];
const attribsSpec = [];
const bindings = [
texture,
];
const vertexShader = (ndx, bindings /* , attribs */) =>
textureSample(bindings[0], ndx * 1.75);
const count = 4;
draw(count, vertexShader, bindings, attribsSpec);
// outputs [10, 27.5, 45, 62.5]
}
section('interStageVariables: calcLine');
{
const line = calcLine([10, 10], [13, 13]);
for (let i = 0; i < line.numPixels; ++i) {
const p = calcLinePoint(line, i);
console.log(p);
}
}
section('interStageVariables: output 2 values per iteration');
{
function getAttribs(attribs, ndx) {
return attribs.map(({source, offset, stride}) => source[ndx * stride + offset]);
}
function draw(count, vertexShaderFn, bindings, attribsSpec) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
const attribs = getAttribs(attribsSpec, i);
internalBuffer[i] = vertexShaderFn(i, bindings, attribs);
}
console.log(JSON.stringify(internalBuffer));
}
const buffer1 = [5, 0, 25, 4];
const attribsSpec = [
{source: buffer1, offset: 0, stride: 2},
{source: buffer1, offset: 1, stride: 2},
];
const bindings = [];
// const dest = new Array(2);
const vertexShader = (ndx, bindings, attribs) => [attribs[0], attribs[1]];
const count = 2;
draw(count, vertexShader, bindings, attribsSpec);
// outputs [[5, 0], [25, 4]]
}
section('interStageVariables: draw line with constant value');
{
function rasterizeLines(dest, destWidth, inputs, fragShaderFn, bindings) {
for (let ndx = 0; ndx < inputs.length - 1; ndx += 2) {
const p0 = inputs[ndx ];
const p1 = inputs[ndx + 1];
const line = calcLine(p0, p1);
for (let i = 0; i < line.numPixels; ++i) {
const p = calcLinePoint(line, i);
const offset = p[1] * destWidth + p[0]; // y * width + x
dest[offset] = fragShaderFn(bindings);
}
}
}
function getAttribs(attribs, ndx) {
return attribs.map(({source, offset, stride}) => source[ndx * stride + offset]);
}
function draw(dest, destWidth,
count, vertexShaderFn, fragmentShaderFn,
bindings, attribsSpec,
) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
const attribs = getAttribs(attribsSpec, i);
internalBuffer[i] = vertexShaderFn(i, bindings, attribs);
}
rasterizeLines(dest, destWidth, internalBuffer,
fragmentShaderFn, bindings);
}
const buffer1 = [5, 0, 25, 4];
const attribsSpec = [
{source: buffer1, offset: 0, stride: 2},
{source: buffer1, offset: 1, stride: 2},
];
const bindings = [];
const vertexShader = (ndx, bindings, attribs) => [attribs[0], attribs[1]];
const count = 2;
const width = 30;
const height = 5;
const pixels = new Array(width * height).fill(0);
const fragShader = (/* bindings */) => 6;
draw(
pixels, width,
count, vertexShader, fragShader,
bindings, attribsSpec);
logArray2D(pixels, width);
}
section('interStageVariables: draw line with varying value');
{
function rasterizeLines(dest, destWidth, inputs, fragShaderFn, bindings) {
for (let ndx = 0; ndx < inputs.length - 1; ndx += 2) {
const p0 = inputs[ndx ][0];
const p1 = inputs[ndx + 1][0];
const v0 = inputs[ndx ].slice(1); // everything but the first value
const v1 = inputs[ndx + 1].slice(1);
const line = calcLine(p0, p1);
for (let i = 0; i < line.numPixels; ++i) {
const p = calcLinePoint(line, i);
const t = i / line.numPixels;
const interStageVariables = interpolateArrays(v0, v1, t);
const offset = p[1] * destWidth + p[0]; // y * width + x
dest[offset] = fragShaderFn(bindings, interStageVariables);
}
}
}
// interpolateArrays([[1,2]], [[3,4]], 0.25) => [[1.5, 2.5]]
function interpolateArrays(v0, v1, t) {
return v0.map((array0, ndx) => {
const array1 = v1[ndx];
return interpolateValues(array0, array1, t);
});
}
// interpolateValues([1,2], [3,4], 0.25) => [1.5, 2.5]
function interpolateValues(array0, array1, t) {
return array0.map((a, ndx) => {
const b = array1[ndx];
return a + (b - a) * t;
});
}
function getAttribs(attribs, ndx) {
return attribs.map(({source, offset, stride}) => source[ndx * stride + offset]);
}
function draw(dest, destWidth,
count, vertexShaderFn, fragmentShaderFn,
uniforms, attribsSpec, bindings,
) {
const internalBuffer = [];
for (let i = 0; i < count; ++i) {
const attribs = getAttribs(attribsSpec, i);
internalBuffer[i] = vertexShaderFn(i, uniforms, attribs, bindings);
}
rasterizeLines(dest, destWidth, internalBuffer,
fragmentShaderFn, uniforms, bindings);
}
const buffer1 = [5, 0, 25, 4];
const buffer2 = [9, 3];
const attribsSpec = [
{source: buffer1, offset: 0, stride: 2},
{source: buffer1, offset: 1, stride: 2},
{source: buffer2, offset: 0, stride: 1},
];
const bindings = [];
// const dest = new Array(2);
const vertexShader = (ndx, uniforms, attribs /* , bindings */) =>
[[attribs[0], attribs[1]], [attribs[2]]];
//const uniforms = {};
const count = 2;
const width = 30;
const height = 5;
const pixels = new Array(width * height).fill(0);
const fragShader = (bindings, interStageVariables) =>
interStageVariables[0] | 0;
draw(
pixels, width,
count, vertexShader, fragShader,
bindings, attribsSpec);
logArray2D(pixels, width);
}
function int(v) {
return v | 0;
}
function calcLine(p1, p2) {
const deltaInc = p1.map((v, ndx) => {
const d = int(p2[ndx]) - int(v);
return {delta: Math.abs(d), inc: Math.sign(d)};
});
const mainAxis = deltaInc[0].delta > deltaInc[1].delta ? 0 : 1;
const minAxis = 1 - mainAxis;
const minDelta = deltaInc[minAxis].delta;
const minInc = deltaInc[minAxis].inc;
const mainInc = deltaInc[mainAxis].inc;
const numPixels = deltaInc[mainAxis].delta;
return {
p1: p1.map(v => int(v)),
mainAxis,
numPixels,
minDelta,
minInc,
mainInc,
};
}
function calcLinePoint(line, i) {
const {p1, mainAxis, numPixels, minDelta, minInc, mainInc} = line;
const minAxis = 1 - mainAxis;
const accum = int(numPixels / 2) + minDelta * i;
const p = p1.slice();
p[mainAxis] += mainInc * i;
p[minAxis] += int(minInc * (accum / numPixels));
return p;
}
function section(heading) {
console.log(`\n======= [ ${heading} ] =======`);
}
function logArray2D(arr, width) {
const lines = [];
for (let i = 0; i < arr.length; i += width) {
lines.push(arr.slice(i, i + width).map(v => v || '.').join(''));
}
console.log(lines.join('\n'));
}
</script>