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image_generate_shadow.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="inspectorGraphCanvas"></canvas>
<script>
function mat4_create() {
let out = new Float32Array(16);
out[0] = 1;
out[5] = 1;
out[10] = 1;
out[15] = 1;
return out;
}
function mat4_ortho(out, left, right, bottom, top, near, far) {
let lr = 1 / (left - right);
let bt = 1 / (bottom - top);
let nf = 1 / (near - far);
out[0] = -2 * lr;
out[1] = 0;
out[2] = 0;
out[3] = 0;
out[4] = 0;
out[5] = -2 * bt;
out[6] = 0;
out[7] = 0;
out[8] = 0;
out[9] = 0;
out[10] = 2 * nf;
out[11] = 0;
out[12] = (left + right) * lr;
out[13] = (top + bottom) * bt;
out[14] = (far + near) * nf;
out[15] = 1;
return out;
}
const canvas = document.getElementById('inspectorGraphCanvas');
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-dpi 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;
}
})();
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, vs: vertexShader, fs: fragmentShader };
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;
}
/* if you're going to use this multiple times in a single program,
* consider modifying it to not immediately delete all the shaders.
*
* or just take the shader compilation hit -- i don't care what you do.
*
* note, if you don't care about supporting Safari, you can generate shadows entirely in canvas
* https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/filter
*
*/
function shadowForTexture(texture, texture_width, texture_height, texture_pad) {
/* compile shaders */
let shaders;
{
const vs_img = `
attribute vec3 a_pos;
attribute vec2 a_uv;
uniform mat4 u_matrix;
varying vec2 v_uv;
void main() {
gl_Position = u_matrix * vec4(a_pos.xyz, 1);
v_uv = a_uv;
}`;
const fs_img = `
precision mediump float;
varying vec2 v_uv;
uniform sampler2D u_texture;
uniform vec2 u_mask;
void main() {
gl_FragColor = texture2D(u_texture, v_uv);
gl_FragColor.xyz *= u_mask.x;
gl_FragColor.w *= u_mask.y;
}`;
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, 0, 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;
}
`;
shaders = {
img: createProgram(gl, vs_img , fs_img ),
fullscreen_blur: createProgram(gl, vs_fullscreen_blur, fs_fullscreen_blur),
};
}
let prebaked;
{
/* some suggestions on AA/multisampling https://stackoverflow.com/a/55976760 */
const canvas_width = texture_width + texture_pad*2;
const canvas_height = texture_height + texture_pad*2;
gl.viewport(
0,
0,
canvas_width,
canvas_height
);
/* this way we can just draw the image from (0, 0)..(width,height)
* and it will have even padding on all sides */
const pMatrix = mat4_ortho(
mat4_create(),
-texture_pad,
texture_width+texture_pad,
-texture_pad,
texture_height+texture_pad,
1,
-1
);
const render_targets = [
{ tex: gl.createTexture(), fb: gl.createFramebuffer() },
{ tex: gl.createTexture(), fb: gl.createFramebuffer() },
];
for (const rt of render_targets) {
gl.bindTexture(gl.TEXTURE_2D, rt.tex);
// Upload the image into the texture.
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 */ null
);
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);
gl.bindFramebuffer(gl.FRAMEBUFFER, rt.fb);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, rt.tex, 0);
}
/* prebaked rt is bound */
const img_vbuf_pos = gl.createBuffer();
const img_vbuf_uv = gl.createBuffer();
const img_ibuf = gl.createBuffer();
{
const img_idx = [];
const img_pos = [];
const img_uv = [];
{
const min_x = 0;
const min_y = 0;
const max_x = texture_width;
const max_y = texture_height;
img_uv.push(
1, 0,
0, 0,
0, 1,
1, 1
);
const vbuf_i = img_pos.length / 3;
img_pos.push(max_x, min_y, 0.1);
img_pos.push(min_x, min_y, 0.1);
img_pos.push(min_x, max_y, 0.1);
img_pos.push(max_x, max_y, 0.1);
img_idx.push(vbuf_i + 0, vbuf_i + 1, vbuf_i + 2, vbuf_i + 2, vbuf_i + 3, vbuf_i + 0);
}
/* set up premultiplied alpha */
gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
gl.enable(gl.DEPTH_TEST);
gl.depthFunc(gl.LEQUAL);
/* clear all */
gl.clearColor(0, 0, 0, 0);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
/* shadow img pass (see color mask) */
function imgPass(u_color_mask, u_alpha_mask) {
gl.useProgram(shaders.img.program);
gl.enableVertexAttribArray(shaders.img.a_pos);
gl.enableVertexAttribArray(shaders.img.a_uv);
/* upload/bind atlas */
{
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.uniform1i(shaders.img.u_texture, 0);
}
gl.uniformMatrix4fv(shaders.img.u_matrix, false, pMatrix);
gl.uniform2f(shaders.img.u_mask, u_color_mask, u_alpha_mask);
/* upload/bind geometry */
{
gl.bindBuffer(gl.ARRAY_BUFFER, img_vbuf_pos);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(img_pos), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.img.a_pos, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, img_vbuf_uv);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(img_uv), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.img.a_uv, 2, gl.FLOAT, true, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, img_ibuf);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(img_idx), gl.STATIC_DRAW);
}
gl.drawElements(gl.TRIANGLES, img_idx.length, gl.UNSIGNED_SHORT, 0);
}
imgPass(0.08, 0.5);
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
/* blur time */
{
const passes = [
// [render_targets[1].fb, render_targets[0].tex, [ 0, 10]],
// [render_targets[0].fb, render_targets[1].tex, [ 9, 0]],
// [render_targets[1].fb, render_targets[0].tex, [ 0, 8]],
[render_targets[0].fb, render_targets[1].tex, [ 7, 0]],
[render_targets[1].fb, render_targets[0].tex, [ 0, 6]],
[render_targets[0].fb, render_targets[1].tex, [ 5, 0]],
[render_targets[1].fb, render_targets[0].tex, [ 0, 4]],
[render_targets[0].fb, render_targets[1].tex, [ 3, 0]],
[render_targets[1].fb, render_targets[0].tex, [ 0, 2]],
[render_targets[0].fb, render_targets[1].tex, [ 1, 0]]
];
for (const [dst_fb, src_tex, dir] of passes) {
gl.bindFramebuffer(gl.FRAMEBUFFER, dst_fb);
gl.useProgram(shaders.fullscreen_blur.program);
gl.uniform2fv(shaders.fullscreen_blur.u_direction, [dir[0]*2, dir[1]*2]);
/* bind tex */
{
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, src_tex);
gl.uniform1i(shaders.fullscreen_blur.u_texture, 0);
}
gl.drawArrays(gl.TRIANGLE_FAN, 0, 3);
}
}
gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
imgPass(1, 1);
}
gl.deleteBuffer(img_vbuf_pos);
gl.deleteBuffer(img_vbuf_uv );
gl.deleteBuffer(img_ibuf );
gl.deleteProgram(shaders.img.program);
gl.deleteShader(shaders.img.vs);
gl.deleteShader(shaders.img.fs);
gl.deleteProgram(shaders.fullscreen_blur.program);
gl.deleteShader(shaders.fullscreen_blur.vs);
gl.deleteShader(shaders.fullscreen_blur.fs);
gl.deleteFramebuffer(render_targets[0].fb);
gl.deleteFramebuffer(render_targets[1].fb);
gl.deleteTexture(render_targets[1].tex);
prebaked = render_targets[0].tex;
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
}
return prebaked;
}
class PopupRenderer {
constructor(gl) {
const img_vbuf_pos = this.img_vbuf_pos = gl.createBuffer();
const img_vbuf_uv = this.img_vbuf_uv = gl.createBuffer();
const img_ibuf = this.img_ibuf = gl.createBuffer();
/* compile shaders */
let shaders;
{
const vsImg = `
attribute vec3 a_pos;
attribute vec2 a_uv;
uniform mat4 u_matrix;
varying vec2 v_uv;
void main() {
gl_Position = u_matrix * vec4(a_pos.xyz, 1);
v_uv = a_uv;
}`;
const fsImg = `
precision mediump float;
varying vec2 v_uv;
uniform sampler2D u_texture;
void main() {
gl_FragColor = texture2D(u_texture, v_uv);
}`;
shaders = this.shaders = {
img: createProgram(gl, vsImg, fsImg),
};
}
let atlas = gl.createTexture();
{
const canvas = document.createElement("canvas");
const SIZE = canvas.width = canvas.height = 500;
const ctx = canvas.getContext("2d");
const PAD = SIZE*0.2;
ctx.font = (SIZE - PAD*2) + 'px sans-serif';
ctx.fillText('🌡️', PAD, SIZE - PAD*2);
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);
}
this.prebaked = shadowForTexture(atlas, 500, 500, 50);
gl.deleteTexture(atlas);
this.img_idx = [];
this.img_pos = [];
this.img_uv = [];
}
drawBox(
min_x, min_y,
max_x, max_y,
min_u, min_v,
max_u, max_v
) {
const vbuf_i = this.img_pos.length / 3;
this.img_pos.push(max_x, min_y, 0.1);
this.img_pos.push(min_x, min_y, 0.1);
this.img_pos.push(min_x, max_y, 0.1);
this.img_pos.push(max_x, max_y, 0.1);
this.img_uv .push(max_u, min_v);
this.img_uv .push(min_u, min_v);
this.img_uv .push(min_u, max_v);
this.img_uv .push(max_u, max_v);
this.img_idx.push(vbuf_i + 0, vbuf_i + 1, vbuf_i + 2, vbuf_i + 2, vbuf_i + 3, vbuf_i + 0);
}
render(gl) {
const { shaders } = this;
gl.viewport(
0,
0,
canvas.width,
canvas.height
);
/* set up premultiplied alpha */
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
/* clear all */
gl.clearColor(0.2, 0.2, 0.2, 1);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
/* geo pass */
{
gl.useProgram(shaders.img.program);
gl.enableVertexAttribArray(shaders.img.a_pos);
gl.enableVertexAttribArray(shaders.img.a_uv);
const pMatrix = mat4_ortho(mat4_create(), 0, gl.canvas.width, gl.canvas.height, 0, 1, -1);
gl.uniformMatrix4fv(shaders.img.u_matrix, false, pMatrix);
{
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, this.prebaked);
gl.uniform1i(shaders.img.u_texture, 0);
}
/* upload/bind geometry */
{
gl.bindBuffer(gl.ARRAY_BUFFER, this.img_vbuf_pos);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(this.img_pos), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.img.a_pos, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, this.img_vbuf_uv);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(this.img_uv), gl.STATIC_DRAW);
gl.vertexAttribPointer(shaders.img.a_uv, 2, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, this.img_ibuf);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(this.img_idx), gl.STATIC_DRAW);
}
gl.drawElements(gl.TRIANGLES, this.img_idx.length, gl.UNSIGNED_SHORT, 0);
}
/* prepare for next frame */
this.img_idx = [];
this.img_pos = [];
this.img_uv = [];
}
}
const pr = new PopupRenderer(gl, canvas);
requestAnimationFrame(function frame(timestamp) {
requestAnimationFrame(frame);
for (let i = 0; i < 50; i++) {
const r = i/50 * Math.PI*2;
const x = Math.cos(r) * 500;
const y = Math.sin(r) * 500;
pr.drawBox(
x + 500,
y + 500,
x + 500+500,
y + 500+500,
0, 0, 1, 1
);
}
pr.render(gl);
})
</script>
</body>
</html>