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fire.js
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fire.js
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const WIDTH = 512;
const HEIGHT = 256;
const QUAD = new Float32Array([-1, -1, +1, -1, -1, +1, +1, +1]);
const PALETTE = new Uint8Array([
0x07, 0x07, 0x07, 0x1F, 0x07, 0x07, 0x2F, 0x0F, 0x07, 0x47, 0x0F, 0x07,
0x57, 0x17, 0x07, 0x67, 0x1F, 0x07, 0x77, 0x1F, 0x07, 0x8F, 0x27, 0x07,
0x9F, 0x2F, 0x07, 0xAF, 0x3F, 0x07, 0xBF, 0x47, 0x07, 0xC7, 0x47, 0x07,
0xDF, 0x4F, 0x07, 0xDF, 0x57, 0x07, 0xDF, 0x57, 0x07, 0xD7, 0x5F, 0x07,
0xD7, 0x5F, 0x07, 0xD7, 0x67, 0x0F, 0xCF, 0x6F, 0x0F, 0xCF, 0x77, 0x0F,
0xCF, 0x7F, 0x0F, 0xCF, 0x87, 0x17, 0xC7, 0x87, 0x17, 0xC7, 0x8F, 0x17,
0xC7, 0x97, 0x1F, 0xBF, 0x9F, 0x1F, 0xBF, 0x9F, 0x1F, 0xBF, 0xA7, 0x27,
0xBF, 0xA7, 0x27, 0xBF, 0xAF, 0x2F, 0xB7, 0xAF, 0x2F, 0xB7, 0xB7, 0x2F,
0xB7, 0xB7, 0x37, 0xCF, 0xCF, 0x6F, 0xDF, 0xDF, 0x9F, 0xEF, 0xEF, 0xC7,
0xFF, 0xFF, 0xFF
]);
const DEPTH = PALETTE.length / 3;
/* The state is an RGB image only using the red channel. Values range
* from 0 to 1 and are mapped back onto the 37-element palette.
*/
const STATE_RENDER = {
vert: `precision mediump float;
attribute vec2 a_point;
varying vec2 v_point;
void main() {
v_point = (a_point + 1.0) / 2.0;
gl_Position = vec4(a_point, 0, 1);
}`,
frag: `precision mediump float;
uniform sampler2D u_state;
uniform sampler2D u_palette;
varying vec2 v_point;
void main() {
float v = texture2D(u_state, v_point).r;
vec4 color = texture2D(u_palette, vec2(v, 0));
gl_FragColor = vec4(color);
}`,
};
/* Writes the next state into the framebuffer from the current state,
* which is bound to active texture 0.
*
* u_temperature and u_flame_height are tweakable parameters.
*
* u_random feeds new entropy into the system.
*/
const STATE_UPDATE = {
vert: `precision mediump float;
attribute vec2 a_point;
varying vec2 v_point;
void main() {
v_point = (a_point + 1.0) / 2.0;
gl_Position = vec4(a_point, 0, 1);
}`,
frag: `precision mediump float;
uniform sampler2D u_state;
uniform float u_temperature;
uniform float u_flame_height;
uniform vec4 u_random;
varying vec2 v_point;
float get(vec2 p) {
float depth = float(${DEPTH - 1});
vec2 scale = vec2(${WIDTH - 1}, ${HEIGHT - 1});
return floor(texture2D(u_state, p / scale).r * depth + 0.5);
}
float rand(vec2 s) {
s += v_point;
float a = sin(dot(v_point + s, vec2(12.9898, 78.233)));
return fract(fract(a * 41.0744) * 86.9083);
}
void main() {
vec2 scale = vec2(${WIDTH - 1}, ${HEIGHT - 1});
vec2 pos = floor(v_point * scale + 0.5);
if (pos.y == 0.0) {
gl_FragColor = vec4(u_temperature, 0, 0, 0);
} else {
float dx = floor(rand(u_random.xy) * 3.0) - 1.0;
float dy = floor(rand(u_random.zw) * 3.0) - 2.0;
float r = floor(rand(u_random.wx) + 1.0 - u_flame_height);
float v = get(pos + vec2(dx, dy)) - r;
float depth = float(${DEPTH - 1});
gl_FragColor = vec4(v / depth, 0, 0, 0);
}
}`,
};
function compile(gl, vert, frag) {
let v = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(v, vert);
let f = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(f, frag);
gl.compileShader(v);
if (!gl.getShaderParameter(v, gl.COMPILE_STATUS))
throw new Error(gl.getShaderInfoLog(v));
gl.compileShader(f);
if (!gl.getShaderParameter(f, gl.COMPILE_STATUS))
throw new Error(gl.getShaderInfoLog(f));
let p = gl.createProgram();
gl.attachShader(p, v);
gl.attachShader(p, f);
gl.linkProgram(p);
if (!gl.getProgramParameter(p, gl.LINK_STATUS))
throw new Error(gl.getProgramInfoLog(p));
gl.deleteShader(v);
gl.deleteShader(f);
let result = {
program: p
};
let nattrib = gl.getProgramParameter(p, gl.ACTIVE_ATTRIBUTES);
for (let a = 0; a < nattrib; a++) {
let name = gl.getActiveAttrib(p, a).name;
result[name] = gl.getAttribLocation(p, name);
}
let nuniform = gl.getProgramParameter(p, gl.ACTIVE_UNIFORMS);
for (let u = 0; u < nuniform; u++) {
let name = gl.getActiveUniform(p, u).name;
result[name] = gl.getUniformLocation(p, name);
}
return result;
};
function Fire(gl) {
let quad = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, quad);
gl.bufferData(gl.ARRAY_BUFFER, QUAD, gl.STATIC_DRAW);
let state0 = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, state0);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texImage2D(
gl.TEXTURE_2D,
0, gl.RGBA,
WIDTH, HEIGHT,
0, gl.RGBA,
gl.UNSIGNED_BYTE,
null
);
let state1 = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, state1);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texImage2D(
gl.TEXTURE_2D,
0, gl.RGBA,
WIDTH, HEIGHT,
0, gl.RGBA,
gl.UNSIGNED_BYTE,
null
);
let palette = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, palette);
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.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texImage2D(
gl.TEXTURE_2D,
0, gl.RGB,
DEPTH, 1,
0, gl.RGB,
gl.UNSIGNED_BYTE,
PALETTE
);
let fb = gl.createFramebuffer();
let update = compile(gl, STATE_UPDATE.vert, STATE_UPDATE.frag);
let render = compile(gl, STATE_RENDER.vert, STATE_RENDER.frag);
gl.bindTexture(gl.TEXTURE_2D, null);
gl.bindBuffer(gl.ARRAY_BUFFER, null);
let self = {
temperature: 1.0, // 0.0 - 1.0
flame_height: 0.75, // 0.0 - 1.0
update: function() {
gl.useProgram(update.program);
gl.uniform1f(update.u_temperature, self.temperature);
gl.uniform1f(update.u_flame_height, self.flame_height);
gl.uniform4f(
update.u_random,
Math.random(),
Math.random(),
Math.random(),
Math.random()
);
gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
gl.framebufferTexture2D(
gl.FRAMEBUFFER,
gl.COLOR_ATTACHMENT0,
gl.TEXTURE_2D,
state1,
0
);
gl.viewport(0, 0, WIDTH, HEIGHT);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, state0);
gl.uniform1i(update.u_state, 0);
gl.enableVertexAttribArray(render.a_point);
gl.bindBuffer(gl.ARRAY_BUFFER, quad);
gl.vertexAttribPointer(render.a_point, 2, gl.FLOAT, false, 0, 0);
gl.drawArrays(gl.TRIANGLE_STRIP, 0, QUAD.length / 2);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
gl.bindBuffer(gl.ARRAY_BUFFER, null);
gl.useProgram(null);
[state0, state1] = [state1, state0]; // swap old and new
},
render: function() {
gl.clear(gl.COLOR_BUFFER_BIT);
gl.viewport(0, 0, gl.drawingBufferWidth, gl.drawingBufferHeight);
gl.useProgram(render.program);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, state0);
gl.uniform1i(render.u_state, 0);
gl.activeTexture(gl.TEXTURE1);
gl.bindTexture(gl.TEXTURE_2D, palette);
gl.uniform1i(render.u_palette, 1);
gl.enableVertexAttribArray(render.a_point);
gl.bindBuffer(gl.ARRAY_BUFFER, quad);
gl.vertexAttribPointer(render.a_point, 2, gl.FLOAT, false, 0, 0);
gl.drawArrays(gl.TRIANGLE_STRIP, 0, QUAD.length / 2);
/* Cleanup */
gl.bindBuffer(gl.ARRAY_BUFFER, null);
gl.useProgram(null);
},
clear: function() {
gl.bindTexture(gl.TEXTURE_2D, state0);
gl.texSubImage2D(
gl.TEXTURE_2D,
0, 0, 0,
WIDTH, HEIGHT,
gl.RGBA,
gl.UNSIGNED_BYTE,
new Uint8Array(WIDTH * HEIGHT * 4)
);
gl.bindTexture(gl.TEXTURE_2D, null);
},
destroy: function() {
gl.deleteProgram(update.program);
gl.deleteProgram(render.program);
gl.deleteBuffer(quad);
gl.deleteTexture(state0);
gl.deleteTexture(state1);
gl.deleteTexture(palette);
gl.deleteFramebuffer(fb);
}
};
return self;
}
(function() {
let canvas = document.querySelector('canvas');
let gl = canvas.getContext('webgl');
let fire = new Fire(gl);
let running = true;
let dirty = false;
let period = 1000 / 70; // 70 FPS (max)
let last = 0;
window.addEventListener('keyup', function(e) {
switch (e.which) {
case 32: /* Space */
running = !running;
break;
case 33: /* PgUp */
fire.temperature = Math.min(fire.temperature + 0.1, 1);
break;
case 34: /* PgDown */
fire.temperature = Math.max(fire.temperature - 0.1, 0);
break;
case 38: /* Up */
fire.flame_height = Math.min(1.0, fire.flame_height += 0.05);
console.log(fire.flame_height);
break;
case 40: /* Down */
fire.flame_height = Math.max(0.0, fire.flame_height -= 0.05);
console.log(fire.flame_height);
break;
case 65: /* a */
for (let i = 0; i < 1024; i++)
fire.update();
dirty = true;
break;
case 67: /* c */
fire.clear();
dirty = true;
break;
case 82: /* r */
fire.destroy();
fire = new Fire(gl);
period = 1000 / 70;
dirty = true;
break;
case 107: /* Minus */
case 187:
period *= 1 / 1.2;
console.log(1000 / period + ' fps');
break;
case 109: /* Plus */
case 189:
period *= 1.2;
console.log(1000 / period + ' fps');
break;
case 190: /* Period */
if (running)
running = false;
else
fire.update();
dirty = true;
break;
}
});
function cb(t) {
let ww = window.innerWidth;
let wh = window.innerHeight;
if (canvas.width != ww || canvas.height != wh) {
canvas.width = ww;
canvas.height = wh;
dirty = true;
}
if (running) {
let now = Date.now();
if (now - last > period) {
fire.update();
dirty = true;
last = now;
}
}
if (dirty) {
fire.render();
dirty = false;
}
window.requestAnimationFrame(cb);
}
window.requestAnimationFrame(cb);
}());