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image_atlas_prebake.html
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image_atlas_prebake.html
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<!-- vim: sw=4 ts=4 expandtab smartindent ft=javascript
-->
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>WebGL Demo</title>
<style> document, body { margin: 0px; padding: 0px; overflow: hidden; } </style>
</head>
<body>
<canvas id="glcanvas"></canvas>
<script>
const canvas = document.getElementById('glcanvas');
const gl = canvas.getContext('webgl2', {antialias: true});
if (!gl) { alert('Failed to initialize WebGL'); }
(window.onresize = () => {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
/* account for e.g. high-retina macbook screens */
if (window.devicePixelRatio > 1) {
canvas.style.width = `${canvas.width}px`;
canvas.style.height = `${canvas.height}px`;
canvas.width *= window.devicePixelRatio;
canvas.height *= window.devicePixelRatio;
}
gl.viewport(
0,
0,
canvas.width,
canvas.height
);
})();
const geo_vbuf_pos = gl.createBuffer();
const geo_vbuf_uv = gl.createBuffer();
const geo_ibuf = gl.createBuffer();
let shaders;
/* compile shaders */
{
const vs_geo = `
attribute vec3 a_pos;
attribute vec2 a_uv;
varying vec2 v_uv;
void main() {
gl_Position = vec4(a_pos.xyz, 1);
v_uv = a_uv;
}`;
const fs_geo = `
precision mediump float;
uniform sampler2D u_texture;
uniform float u_brightness;
varying vec2 v_uv;
void main() {
gl_FragColor = texture2D(u_texture, v_uv) * u_brightness;
}`;
const vs_fullscreen_blur = `#version 300 es
precision mediump float;
out vec2 v_texcoord;
void main(void) {
float x = float((gl_VertexID & 1) << 2);
float y = float((gl_VertexID & 2) << 1);
v_texcoord.x = x * 0.5;
v_texcoord.y = y * 0.5;
gl_Position = vec4(x - 1.0, y - 1.0, 1, 1);
}
`;
const fs_fullscreen_blur = `#version 300 es
precision mediump float;
uniform sampler2D u_texture;
uniform vec2 u_direction;
in vec2 v_texcoord;
out vec4 frag_color;
void main(void) {
vec2 one_pixel = u_direction*(vec2(1) / vec2(textureSize(u_texture, 0)));
frag_color = texture(u_texture, v_texcoord) * 0.2270270270;
frag_color += texture(u_texture, v_texcoord + one_pixel ) * 0.1945945946;
frag_color += texture(u_texture, v_texcoord - one_pixel ) * 0.1945945946;
frag_color += texture(u_texture, v_texcoord + one_pixel*2.0) * 0.1216216216;
frag_color += texture(u_texture, v_texcoord - one_pixel*2.0) * 0.1216216216;
frag_color += texture(u_texture, v_texcoord + one_pixel*3.0) * 0.0540540541;
frag_color += texture(u_texture, v_texcoord - one_pixel*3.0) * 0.0540540541;
frag_color += texture(u_texture, v_texcoord + one_pixel*4.0) * 0.0162162162;
frag_color += texture(u_texture, v_texcoord - one_pixel*4.0) * 0.0162162162;
}
`;
function createProgram(gl, vertexSource, fragmentSource) {
function createShader(gl, type, source) {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
throw new Error(gl.getShaderInfoLog(shader));
}
return shader;
}
const program = gl.createProgram();
const vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexSource);
const fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentSource);
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
throw new Error(gl.getProgramInfoLog(program));
}
const wrapper = {program};
const numAttributes = gl.getProgramParameter(program, gl.ACTIVE_ATTRIBUTES);
for (let i = 0; i < numAttributes; i++) {
const attribute = gl.getActiveAttrib(program, i);
wrapper[attribute.name] = gl.getAttribLocation(program, attribute.name);
}
const numUniforms = gl.getProgramParameter(program, gl.ACTIVE_UNIFORMS);
for (let i = 0; i < numUniforms; i++) {
const uniform = gl.getActiveUniform(program, i);
wrapper[uniform.name] = gl.getUniformLocation(program, uniform.name);
}
return wrapper;
}
shaders = {
fullscreenBlur: createProgram(gl, vs_fullscreen_blur, fs_fullscreen_blur),
geo: createProgram(gl, vs_geo, fs_geo)
}
}
let texture_starfield = gl.createTexture();
{
const texture_starfield_size = 2000;
const blur_factor = 0.00075;
const image_brightness = 0.4;
let atlas = gl.createTexture();
const ATLAS_SIZE = 2; /* in emoji */
const EMOJI_SIZE = 300;
{
const canvas = document.createElement("canvas");
canvas.width = canvas.height = ATLAS_SIZE * EMOJI_SIZE;
const ctx = canvas.getContext("2d");
{
const atlas = ['⭐️', '💫', '✨', '🪐'];
const PAD = EMOJI_SIZE*0.05;
ctx.font = (EMOJI_SIZE - PAD*2) + 'px sans-serif';
let i = 0;
for (const char of atlas) {
const x = ( i % ATLAS_SIZE ) * EMOJI_SIZE;
const y = (Math.floor(i / ATLAS_SIZE)) * EMOJI_SIZE;
ctx.fillText(
char,
x + PAD,
y + EMOJI_SIZE - PAD*2
);
i++;
}
}
gl.bindTexture(gl.TEXTURE_2D, atlas);
gl.texImage2D(
/* target */ gl.TEXTURE_2D,
/* level */ 0,
/* internalformat */ gl.RGBA,
/* width */ canvas.width,
/* height */ canvas.height,
/* border, */ 0,
/* format, */ gl.RGBA,
/* type, */ gl.UNSIGNED_BYTE,
/* data */ canvas
);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
}
let render_targets = [
{ tex: null, fb: null },
{ tex: null, fb: null },
];
gl.viewport(
0,
0,
texture_starfield_size,
texture_starfield_size
);
/* create scene-sized render-target for post-processing fx (like shadows) */
for (const target of render_targets) {
target.tex = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, target.tex);
// define size and format of level 0
gl.texImage2D(
gl.TEXTURE_2D,
/* level, */ 0,
/* internalFormat, */ gl.RGBA,
/* width, */ texture_starfield_size,
/* height, */ texture_starfield_size,
/* border, */ 0,
/* format, */ gl.RGBA,
/* type, */ gl.UNSIGNED_BYTE,
/* data */ null
);
// set the filtering so we don't need mips
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
target.fb = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, target.fb);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, target.tex, 0);
}
const geo = {
idx: [],
pos: [],
uv : [],
};
{
function drawBox(x, y, size, atlas_index) {
/* generate UVs from atlas_index */
{
const u = ( atlas_index % ATLAS_SIZE );
const v = (Math.floor(atlas_index / ATLAS_SIZE));
geo.uv.push(
(u+1)/ATLAS_SIZE, (v+1)/ATLAS_SIZE,
(u+0)/ATLAS_SIZE, (v+1)/ATLAS_SIZE,
(u+0)/ATLAS_SIZE, (v+0)/ATLAS_SIZE,
(u+1)/ATLAS_SIZE, (v+0)/ATLAS_SIZE,
);
}
/* generate position + index */
{
const vbuf_i = geo.pos.length / 3;
geo.pos.push(x+size, y-size, 0.1);
geo.pos.push(x-size, y-size, 0.1);
geo.pos.push(x-size, y+size, 0.1);
geo.pos.push(x+size, y+size, 0.1);
geo.idx.push(
vbuf_i + 0,
vbuf_i + 1,
vbuf_i + 2,
vbuf_i + 2,
vbuf_i + 3,
vbuf_i + 0
);
}
}
for (let x = -1; x <= 1; x += 0.1) {
for (let y = -1; y <= 1; y += 0.1) {
drawBox(
x + (0.5 - Math.random())*0.1,
y + (0.5 - Math.random())*0.1,
0.005 + Math.random()*0.008,
~~(Math.random()*4)
);
}
}
}
{
/* clear framebuffers */
{
const BRIGHTNESS = 0.9;
{
gl.bindFramebuffer(gl.FRAMEBUFFER, render_targets[1].fb);
/* clear all */
gl.clearColor(0.0, 0.0, 0.0, 1.0 - BRIGHTNESS);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
}
/* bind first rendertarget in blur swapchain */
{
gl.bindFramebuffer(gl.FRAMEBUFFER, render_targets[0].fb);
/* clear all */
gl.clearColor(0.0, 0.0, 0.0, 1.0 - BRIGHTNESS);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
}
}
/* basic setup */
{
/* set up premultiplied alpha */
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
/* enable depth */
gl.enable(gl.DEPTH_TEST);
gl.depthFunc(gl.LEQUAL);
}
/* geo pass */
function geoPass() {
gl.useProgram(shaders.geo.program);
gl.enableVertexAttribArray(shaders.geo.a_pos);
gl.enableVertexAttribArray(shaders.geo.a_uv);
/* upload/bind atlas */
{
gl.activeTexture(gl.TEXTURE1);
gl.bindTexture(gl.TEXTURE_2D, atlas);
gl.uniform1i(shaders.geo.u_texture, 1);
}
gl.uniform1f(shaders.geo.u_brightness, image_brightness);
/* upload/bind geometry */
{
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_pos);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geo.pos), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_pos, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_uv);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geo.uv), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_uv, 2, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, geo_ibuf);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(geo.idx), gl.STATIC_DRAW);
}
gl.drawElements(gl.TRIANGLES, geo.idx.length, gl.UNSIGNED_SHORT, 0);
}
geoPass();
/* blur passes! */
{
const blur_size = texture_starfield_size * blur_factor;
const passes = [
[render_targets[1].fb, render_targets[0].tex, [0*blur_size, 8*blur_size]],
[render_targets[0].fb, render_targets[1].tex, [7*blur_size, 0*blur_size]],
[render_targets[1].fb, render_targets[0].tex, [0*blur_size, 6*blur_size]],
[render_targets[0].fb, render_targets[1].tex, [5*blur_size, 0*blur_size]],
[render_targets[1].fb, render_targets[0].tex, [0*blur_size, 4*blur_size]],
[render_targets[0].fb, render_targets[1].tex, [3*blur_size, 0*blur_size]],
[render_targets[1].fb, render_targets[0].tex, [0*blur_size, 2*blur_size]],
[render_targets[0].fb, render_targets[1].tex, [1*blur_size, 0*blur_size]]
];
for (const [dst_fb, src_tex, dir] of passes) {
gl.bindFramebuffer(gl.FRAMEBUFFER, dst_fb);
gl.useProgram(shaders.fullscreenBlur.program);
gl.uniform2fv(shaders.fullscreenBlur.u_direction, dir);
/* bind tex */
{
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, src_tex);
gl.uniform1i(shaders.fullscreenBlur.u_texture, 0);
}
gl.drawArrays(gl.TRIANGLE_FAN, 0, 3);
}
}
geoPass();
}
gl.deleteFramebuffer(render_targets[0].fb);
texture_starfield = render_targets[0].tex;
gl.deleteFramebuffer(render_targets[1].fb);
gl.deleteTexture(render_targets[1].tex);
gl.deleteTexture(atlas);
gl.viewport(
0,
0,
canvas.width,
canvas.height
);
}
requestAnimationFrame(function frame(timestamp) {
requestAnimationFrame(frame);
const geo = {
idx: [],
pos: [],
uv : [],
};
{
function drawBox(x, y, size) {
/* generate UVs from atlas_index */
geo.uv.push(
1, 0,
0, 0,
0, 1,
1, 1,
);
/* generate position + index */
{
const vbuf_i = geo.pos.length / 3;
geo.pos.push(x+size, y-size, 0.1);
geo.pos.push(x-size, y-size, 0.1);
geo.pos.push(x-size, y+size, 0.1);
geo.pos.push(x+size, y+size, 0.1);
geo.idx.push(
vbuf_i + 0,
vbuf_i + 1,
vbuf_i + 2,
vbuf_i + 2,
vbuf_i + 3,
vbuf_i + 0
);
}
}
drawBox(0, 0, 0.8, 0);
}
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
/* clear all */
gl.clearColor(1.0, 1.0, 1.0, 1.0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
{
gl.useProgram(shaders.geo.program);
gl.enableVertexAttribArray(shaders.geo.a_pos);
gl.enableVertexAttribArray(shaders.geo.a_uv);
/* upload/bind atlas */
{
gl.activeTexture(gl.TEXTURE1);
gl.bindTexture(gl.TEXTURE_2D, texture_starfield);
gl.uniform1i(shaders.geo.u_texture, 1);
}
gl.uniform1f(shaders.geo.u_brightness, 1);
/* upload/bind geometry */
{
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_pos);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geo.pos), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_pos, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, geo_vbuf_uv);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geo.uv), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.geo.a_uv, 2, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, geo_ibuf);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(geo.idx), gl.STATIC_DRAW);
}
gl.drawElements(gl.TRIANGLES, geo.idx.length, gl.UNSIGNED_SHORT, 0);
}
})
</script>
</body>
</html>