（转载）如何实现网站鼠标特效
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使用以下代码可以实现一个在画布上的鼠标特效
"use strict";
const canvas = document.getElementsByTagName("canvas")[0];
canvas.width = canvas.clientWidth;
canvas.height = canvas.clientHeight;
Array.prototype.getRandom = function () {
return this[Math.floor(Math.random() * this.length)];
};
let splatColors = [{ r: 0, g: 0.15, b: 0 }];
let idleSplats;
function idleSplatsFunction() {
multipleSplats(
parseInt(Math.random() * config.RANDOM_AMOUNT) +
config.RANDOM_AMOUNT / 2 +
1
);
}
let config = {
SIM_RESOLUTION: 256,
DYE_RESOLUTION: 1024,
DENSITY_DISSIPATION: 0.97,
VELOCITY_DISSIPATION: 0.98,
PRESSURE_DISSIPATION: 0.8,
PRESSURE_ITERATIONS: 20,
CURL: 30,
SPLAT_RADIUS: 0.3,
SHADING: true,
COLORFUL: true,
PAUSED: false,
BACK_COLOR: { r: 0, g: 0, b: 0 },
TRANSPARENT: false,
BLOOM: true,
BLOOM_ITERATIONS: 8,
BLOOM_RESOLUTION: 256,
BLOOM_INTENSITY: 0.8,
BLOOM_THRESHOLD: 0.6,
BLOOM_SOFT_KNEE: 0.7,
POINTER_COLOR: [{ r: 0, g: 0.15, b: 0 }],
SOUND_SENSITIVITY: 0.25,
AUDIO_RESPONSIVE: true,
FREQ_RANGE: 8,
FREQ_RANGE_START: 0,
IDLE_SPLATS: false,
RANDOM_AMOUNT: 10,
RANDOM_INTERVAL: 1,
SPLAT_ON_CLICK: true,
SHOW_MOUSE_MOVEMENT: true,
};
document.addEventListener("DOMContentLoaded", () => {
window.wallpaperPropertyListener = {
applyUserProperties: (properties) => {
if (properties.bloom_intensity)
config.BLOOM_INTENSITY = properties.bloom_intensity.value;
if (properties.bloom_threshold)
config.BLOOM_THRESHOLD = properties.bloom_threshold.value;
if (properties.colorful) config.COLORFUL = properties.colorful.value;
if (properties.density_diffusion)
config.DENSITY_DISSIPATION = properties.density_diffusion.value;
if (properties.enable_bloom) config.BLOOM = properties.enable_bloom.value;
if (properties.paused) config.PAUSED = properties.paused.value;
if (properties.pressure_diffusion)
config.PRESSURE_DISSIPATION = properties.pressure_diffusion.value;
if (properties.shading) config.SHADING = properties.shading.value;
if (properties.splat_radius)
config.SPLAT_RADIUS = properties.splat_radius.value;
if (properties.velocity_diffusion)
config.VELOCITY_DISSIPATION = properties.velocity_diffusion.value;
if (properties.vorticity) config.CURL = properties.vorticity.value;
if (properties.sound_sensitivity)
config.SOUND_SENSITIVITY = properties.sound_sensitivity.value;
if (properties.audio_responsive)
config.AUDIO_RESPONSIVE = properties.audio_responsive.value;
if (properties.simulation_resolution) {
config.SIM_RESOLUTION = properties.simulation_resolution.value;
initFramebuffers();
}
if (properties.dye_resolution) {
config.DYE_RESOLUTION = properties.dye_resolution.value;
initFramebuffers();
}
if (properties.splat_color) {
splatColors[0] = rgbToPointerColor(properties.splat_color.value);
if (!config.COLORFUL) config.POINTER_COLOR = [splatColors[0]];
}
if (properties.splat_color_2)
splatColors[1] = rgbToPointerColor(properties.splat_color_2.value);
if (properties.splat_color_3)
splatColors[2] = rgbToPointerColor(properties.splat_color_3.value);
if (properties.splat_color_4)
splatColors[3] = rgbToPointerColor(properties.splat_color_4.value);
if (properties.splat_color_5)
splatColors[4] = rgbToPointerColor(properties.splat_color_5.value);
if (properties.background_color) {
let c = properties.background_color.value.split(" "),
r = Math.floor(c[0] * 255),
g = Math.floor(c[1] * 255),
b = Math.floor(c[2] * 255);
document.body.style.backgroundColor = `rgb(${r}, ${g}, ${b})`;
config.BACK_COLOR.r = r;
config.BACK_COLOR.g = g;
config.BACK_COLOR.b = b;
}
if (properties.more_colors && !properties.more_colors.value) {
config.POINTER_COLOR = [splatColors[0]];
} else if (properties.more_colors && properties.more_colors.value) {
config.POINTER_COLOR = splatColors;
}
if (properties.use_background_image)
config.TRANSPARENT = properties.use_background_image.value;
if (properties.background_image)
canvas.style.backgroundImage = `url("file:///${properties.background_image.value}")`;
if (properties.repeat_background)
canvas.style.backgroundRepeat = properties.repeat_background.value
? "repeat"
: "no-repeat";
if (properties.background_image_size)
canvas.style.backgroundSize = properties.background_image_size.value;
if (properties.frequency_range) {
config.FREQ_RANGE = properties.frequency_range.value;
if (config.FREQ_RANGE + config.FREQ_RANGE_START > 61) {
config.FREQ_RANGE_START = 62 - config.FREQ_RANGE;
}
}
if (properties.frequency_range_start) {
if (config.FREQ_RANGE + properties.frequency_range_start.value > 61) {
config.FREQ_RANGE_START = 62 - config.FREQ_RANGE;
} else {
config.FREQ_RANGE_START = properties.frequency_range_start.value;
}
}
if (properties.idle_random_splats) {
config.IDLE_SPLATS = properties.idle_random_splats.value;
if (properties.idle_random_splats.value) {
idleSplats = setInterval(
idleSplatsFunction,
config.RANDOM_INTERVAL * 1000
);
} else {
clearInterval(idleSplats);
}
}
if (properties.random_splat_interval) {
config.RANDOM_INTERVAL = properties.random_splat_interval.value;
if (config.IDLE_SPLATS) {
clearInterval(idleSplats);
idleSplats = setInterval(
idleSplatsFunction,
config.RANDOM_INTERVAL * 1000
);
}
}
if (properties.random_splat_amount) {
config.RANDOM_AMOUNT = properties.random_splat_amount.value;
if (config.IDLE_SPLATS) {
clearInterval(idleSplats);
idleSplats = setInterval(
idleSplatsFunction,
config.RANDOM_INTERVAL * 1000
);
}
}
if (properties.splat_on_click)
config.SPLAT_ON_CLICK = properties.splat_on_click.value;
if (properties.show_mouse_movement)
config.SHOW_MOUSE_MOVEMENT = properties.show_mouse_movement.value;
},
};
window.wallpaperRegisterAudioListener((audioArray) => {
if (!config.AUDIO_RESPONSIVE) return;
if (audioArray[0] > 5) return;
let bass = 0.0;
let half = Math.floor(audioArray.length / 2);
for (let i = 0; i <= config.FREQ_RANGE; i++) {
bass += audioArray[i + config.FREQ_RANGE_START];
bass += audioArray[half + (i + config.FREQ_RANGE_START)];
}
bass /= config.FREQ_RANGE * 2;
multipleSplats(Math.floor(bass * config.SOUND_SENSITIVITY * 10));
});
});
function indexOfMax(arr) {
if (arr.length === 0) {
return -1;
}
var max = arr[0];
var maxIndex = 0;
for (var i = 1; i < arr.length; i++) {
if (arr[i] > max) {
maxIndex = i;
max = arr[i];
}
}
return maxIndex;
}
class pointerPrototype {
constructor() {
this.id = -1;
this.x = 0;
this.y = 0;
this.dx = 0;
this.dy = 0;
this.down = false;
this.moved = false;
this.color = config.COLORFUL
? generateColor()
: config.POINTER_COLOR.getRandom();
}
}
let pointers = [];
let splatStack = [];
let bloomFramebuffers = [];
pointers.push(new pointerPrototype());
const { gl, ext } = getWebGLContext(canvas);
if (isMobile()) config.SHADING = false;
if (!ext.supportLinearFiltering) {
config.SHADING = false;
config.BLOOM = false;
}
function getWebGLContext(canvas) {
const params = {
alpha: true,
depth: false,
stencil: false,
antialias: false,
preserveDrawingBuffer: false,
};
let gl = canvas.getContext("webgl2", params);
const isWebGL2 = !!gl;
if (!isWebGL2)
gl =
canvas.getContext("webgl", params) ||
canvas.getContext("experimental-webgl", params);
let halfFloat;
let supportLinearFiltering;
if (isWebGL2) {
gl.getExtension("EXT_color_buffer_float");
supportLinearFiltering = gl.getExtension("OES_texture_float_linear");
} else {
halfFloat = gl.getExtension("OES_texture_half_float");
supportLinearFiltering = gl.getExtension("OES_texture_half_float_linear");
}
gl.clearColor(0.0, 0.0, 0.0, 1.0);
const halfFloatTexType = isWebGL2 ? gl.HALF_FLOAT : halfFloat.HALF_FLOAT_OES;
let formatRGBA;
let formatRG;
let formatR;
if (isWebGL2) {
formatRGBA = getSupportedFormat(gl, gl.RGBA16F, gl.RGBA, halfFloatTexType);
formatRG = getSupportedFormat(gl, gl.RG16F, gl.RG, halfFloatTexType);
formatR = getSupportedFormat(gl, gl.R16F, gl.RED, halfFloatTexType);
} else {
formatRGBA = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
formatRG = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
formatR = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
}
return {
gl,
ext: {
formatRGBA,
formatRG,
formatR,
halfFloatTexType,
supportLinearFiltering,
},
};
}
function getSupportedFormat(gl, internalFormat, format, type) {
if (!supportRenderTextureFormat(gl, internalFormat, format, type)) {
switch (internalFormat) {
case gl.R16F:
return getSupportedFormat(gl, gl.RG16F, gl.RG, type);
case gl.RG16F:
return getSupportedFormat(gl, gl.RGBA16F, gl.RGBA, type);
default:
return null;
}
}
return {
internalFormat,
format,
};
}
function supportRenderTextureFormat(gl, internalFormat, format, type) {
let texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
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.texImage2D(gl.TEXTURE_2D, 0, internalFormat, 4, 4, 0, format, type, null);
let fbo = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
gl.framebufferTexture2D(
gl.FRAMEBUFFER,
gl.COLOR_ATTACHMENT0,
gl.TEXTURE_2D,
texture,
0
);
const status = gl.checkFramebufferStatus(gl.FRAMEBUFFER);
if (status != gl.FRAMEBUFFER_COMPLETE) return false;
return true;
}
function isMobile() {
return /Mobi|Android/i.test(navigator.userAgent);
}
class GLProgram {
constructor(vertexShader, fragmentShader) {
this.uniforms = {};
this.program = gl.createProgram();
gl.attachShader(this.program, vertexShader);
gl.attachShader(this.program, fragmentShader);
gl.linkProgram(this.program);
if (!gl.getProgramParameter(this.program, gl.LINK_STATUS))
throw gl.getProgramInfoLog(this.program);
const uniformCount = gl.getProgramParameter(
this.program,
gl.ACTIVE_UNIFORMS
);
for (let i = 0; i < uniformCount; i++) {
const uniformName = gl.getActiveUniform(this.program, i).name;
this.uniforms[uniformName] = gl.getUniformLocation(
this.program,
uniformName
);
}
}
bind() {
gl.useProgram(this.program);
}
}
function compileShader(type, source) {
const shader = gl.createShader(type);
gl.shaderSource(shader, source);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS))
throw gl.getShaderInfoLog(shader);
return shader;
}
const baseVertexShader = compileShader(
gl.VERTEX_SHADER,
`
precision highp float;
attribute vec2 aPosition;
varying vec2 vUv;
varying vec2 vL;
varying vec2 vR;
varying vec2 vT;
varying vec2 vB;
uniform vec2 texelSize;
void main () {
vUv = aPosition * 0.5 + 0.5;
vL = vUv - vec2(texelSize.x, 0.0);
vR = vUv + vec2(texelSize.x, 0.0);
vT = vUv + vec2(0.0, texelSize.y);
vB = vUv - vec2(0.0, texelSize.y);
gl_Position = vec4(aPosition, 0.0, 1.0);
}
`
);
const clearShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying highp vec2 vUv;
uniform sampler2D uTexture;
uniform float value;
void main () {
gl_FragColor = value * texture2D(uTexture, vUv);
}
`
);
const colorShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
uniform vec4 color;
void main () {
gl_FragColor = color;
}
`
);
const backgroundShader = compileShader(
gl.FRAGMENT_SHADER,
`
void main () {
gl_FragColor = vec4(0.0, 0.0, 0.0, 0.0);
}
`
);
const displayShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
uniform sampler2D uTexture;
void main () {
vec3 C = texture2D(uTexture, vUv).rgb;
float a = max(C.r, max(C.g, C.b));
gl_FragColor = vec4(C, a);
}
`
);
const displayBloomShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
uniform sampler2D uTexture;
uniform sampler2D uBloom;
uniform sampler2D uDithering;
uniform vec2 ditherScale;
void main () {
vec3 C = texture2D(uTexture, vUv).rgb;
vec3 bloom = texture2D(uBloom, vUv).rgb;
bloom = pow(bloom.rgb, vec3(1.0 / 2.2));
C += bloom;
float a = max(C.r, max(C.g, C.b));
gl_FragColor = vec4(C, a);
}
`
);
const displayShadingShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
varying vec2 vL;
varying vec2 vR;
varying vec2 vT;
varying vec2 vB;
uniform sampler2D uTexture;
uniform vec2 texelSize;
void main () {
vec3 L = texture2D(uTexture, vL).rgb;
vec3 R = texture2D(uTexture, vR).rgb;
vec3 T = texture2D(uTexture, vT).rgb;
vec3 B = texture2D(uTexture, vB).rgb;
vec3 C = texture2D(uTexture, vUv).rgb;
float dx = length(R) - length(L);
float dy = length(T) - length(B);
vec3 n = normalize(vec3(dx, dy, length(texelSize)));
vec3 l = vec3(0.0, 0.0, 1.0);
float diffuse = clamp(dot(n, l) + 0.7, 0.7, 1.0);
C.rgb *= diffuse;
float a = max(C.r, max(C.g, C.b));
gl_FragColor = vec4(C, a);
}
`
);
const displayBloomShadingShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
varying vec2 vL;
varying vec2 vR;
varying vec2 vT;
varying vec2 vB;
uniform sampler2D uTexture;
uniform sampler2D uBloom;
uniform sampler2D uDithering;
uniform vec2 ditherScale;
uniform vec2 texelSize;
void main () {
vec3 L = texture2D(uTexture, vL).rgb;
vec3 R = texture2D(uTexture, vR).rgb;
vec3 T = texture2D(uTexture, vT).rgb;
vec3 B = texture2D(uTexture, vB).rgb;
vec3 C = texture2D(uTexture, vUv).rgb;
float dx = length(R) - length(L);
float dy = length(T) - length(B);
vec3 n = normalize(vec3(dx, dy, length(texelSize)));
vec3 l = vec3(0.0, 0.0, 1.0);
float diffuse = clamp(dot(n, l) + 0.7, 0.7, 1.0);
C *= diffuse;
vec3 bloom = texture2D(uBloom, vUv).rgb;
bloom = pow(bloom.rgb, vec3(1.0 / 2.2));
C += bloom;
float a = max(C.r, max(C.g, C.b));
gl_FragColor = vec4(C, a);
}
`
);
const bloomPrefilterShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying vec2 vUv;
uniform sampler2D uTexture;
uniform vec3 curve;
uniform float threshold;
void main () {
vec3 c = texture2D(uTexture, vUv).rgb;
float br = max(c.r, max(c.g, c.b));
float rq = clamp(br - curve.x, 0.0, curve.y);
rq = curve.z * rq * rq;
c *= max(rq, br - threshold) / max(br, 0.0001);
gl_FragColor = vec4(c, 0.0);
}
`
);
const bloomBlurShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying vec2 vL;
varying vec2 vR;
varying vec2 vT;
varying vec2 vB;
uniform sampler2D uTexture;
void main () {
vec4 sum = vec4(0.0);
sum += texture2D(uTexture, vL);
sum += texture2D(uTexture, vR);
sum += texture2D(uTexture, vT);
sum += texture2D(uTexture, vB);
sum *= 0.25;
gl_FragColor = sum;
}
`
);
const bloomFinalShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying vec2 vL;
varying vec2 vR;
varying vec2 vT;
varying vec2 vB;
uniform sampler2D uTexture;
uniform float intensity;
void main () {
vec4 sum = vec4(0.0);
sum += texture2D(uTexture, vL);
sum += texture2D(uTexture, vR);
sum += texture2D(uTexture, vT);
sum += texture2D(uTexture, vB);
sum *= 0.25;
gl_FragColor = sum * intensity;
}
`
);
const splatShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
uniform sampler2D uTarget;
uniform float aspectRatio;
uniform vec3 color;
uniform vec2 point;
uniform float radius;
void main () {
vec2 p = vUv - point.xy;
p.x *= aspectRatio;
vec3 splat = exp(-dot(p, p) / radius) * color;
vec3 base = texture2D(uTarget, vUv).xyz;
gl_FragColor = vec4(base + splat, 1.0);
}
`
);
const advectionManualFilteringShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
uniform sampler2D uVelocity;
uniform sampler2D uSource;
uniform vec2 texelSize;
uniform vec2 dyeTexelSize;
uniform float dt;
uniform float dissipation;
vec4 bilerp (sampler2D sam, vec2 uv, vec2 tsize) {
vec2 st = uv / tsize - 0.5;
vec2 iuv = floor(st);
vec2 fuv = fract(st);
vec4 a = texture2D(sam, (iuv + vec2(0.5, 0.5)) * tsize);
vec4 b = texture2D(sam, (iuv + vec2(1.5, 0.5)) * tsize);
vec4 c = texture2D(sam, (iuv + vec2(0.5, 1.5)) * tsize);
vec4 d = texture2D(sam, (iuv + vec2(1.5, 1.5)) * tsize);
return mix(mix(a, b, fuv.x), mix(c, d, fuv.x), fuv.y);
}
void main () {
vec2 coord = vUv - dt * bilerp(uVelocity, vUv, texelSize).xy * texelSize;
gl_FragColor = dissipation * bilerp(uSource, coord, dyeTexelSize);
gl_FragColor.a = 1.0;
}
`
);
const advectionShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
uniform sampler2D uVelocity;
uniform sampler2D uSource;
uniform vec2 texelSize;
uniform float dt;
uniform float dissipation;
void main () {
vec2 coord = vUv - dt * texture2D(uVelocity, vUv).xy * texelSize;
gl_FragColor = dissipation * texture2D(uSource, coord);
gl_FragColor.a = 1.0;
}
`
);
const divergenceShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying highp vec2 vUv;
varying highp vec2 vL;
varying highp vec2 vR;
varying highp vec2 vT;
varying highp vec2 vB;
uniform sampler2D uVelocity;
void main () {
float L = texture2D(uVelocity, vL).x;
float R = texture2D(uVelocity, vR).x;
float T = texture2D(uVelocity, vT).y;
float B = texture2D(uVelocity, vB).y;
vec2 C = texture2D(uVelocity, vUv).xy;
if (vL.x < 0.0) { L = -C.x; }
if (vR.x > 1.0) { R = -C.x; }
if (vT.y > 1.0) { T = -C.y; }
if (vB.y < 0.0) { B = -C.y; }
float div = 0.5 * (R - L + T - B);
gl_FragColor = vec4(div, 0.0, 0.0, 1.0);
}
`
);
const curlShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying highp vec2 vUv;
varying highp vec2 vL;
varying highp vec2 vR;
varying highp vec2 vT;
varying highp vec2 vB;
uniform sampler2D uVelocity;
void main () {
float L = texture2D(uVelocity, vL).y;
float R = texture2D(uVelocity, vR).y;
float T = texture2D(uVelocity, vT).x;
float B = texture2D(uVelocity, vB).x;
float vorticity = R - L - T + B;
gl_FragColor = vec4(0.5 * vorticity, 0.0, 0.0, 1.0);
}
`
);
const vorticityShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision highp float;
precision highp sampler2D;
varying vec2 vUv;
varying vec2 vL;
varying vec2 vR;
varying vec2 vT;
varying vec2 vB;
uniform sampler2D uVelocity;
uniform sampler2D uCurl;
uniform float curl;
uniform float dt;
void main () {
float L = texture2D(uCurl, vL).x;
float R = texture2D(uCurl, vR).x;
float T = texture2D(uCurl, vT).x;
float B = texture2D(uCurl, vB).x;
float C = texture2D(uCurl, vUv).x;
vec2 force = 0.5 * vec2(abs(T) - abs(B), abs(R) - abs(L));
force /= length(force) + 0.0001;
force *= curl * C;
force.y *= -1.0;
vec2 vel = texture2D(uVelocity, vUv).xy;
gl_FragColor = vec4(vel + force * dt, 0.0, 1.0);
}
`
);
const pressureShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying highp vec2 vUv;
varying highp vec2 vL;
varying highp vec2 vR;
varying highp vec2 vT;
varying highp vec2 vB;
uniform sampler2D uPressure;
uniform sampler2D uDivergence;
vec2 boundary (vec2 uv) {
return uv;
// uncomment if you use wrap or repeat texture mode
// uv = min(max(uv, 0.0), 1.0);
// return uv;
}
void main () {
float L = texture2D(uPressure, boundary(vL)).x;
float R = texture2D(uPressure, boundary(vR)).x;
float T = texture2D(uPressure, boundary(vT)).x;
float B = texture2D(uPressure, boundary(vB)).x;
float C = texture2D(uPressure, vUv).x;
float divergence = texture2D(uDivergence, vUv).x;
float pressure = (L + R + B + T - divergence) * 0.25;
gl_FragColor = vec4(pressure, 0.0, 0.0, 1.0);
}
`
);
const gradientSubtractShader = compileShader(
gl.FRAGMENT_SHADER,
`
precision mediump float;
precision mediump sampler2D;
varying highp vec2 vUv;
varying highp vec2 vL;
varying highp vec2 vR;
varying highp vec2 vT;
varying highp vec2 vB;
uniform sampler2D uPressure;
uniform sampler2D uVelocity;
vec2 boundary (vec2 uv) {
return uv;
// uv = min(max(uv, 0.0), 1.0);
// return uv;
}
void main () {
float L = texture2D(uPressure, boundary(vL)).x;
float R = texture2D(uPressure, boundary(vR)).x;
float T = texture2D(uPressure, boundary(vT)).x;
float B = texture2D(uPressure, boundary(vB)).x;
vec2 velocity = texture2D(uVelocity, vUv).xy;
velocity.xy -= vec2(R - L, T - B);
gl_FragColor = vec4(velocity, 0.0, 1.0);
}
`
);
const blit = (() => {
gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer());
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array([-1, -1, -1, 1, 1, 1, 1, -1]),
gl.STATIC_DRAW
);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, gl.createBuffer());
gl.bufferData(
gl.ELEMENT_ARRAY_BUFFER,
new Uint16Array([0, 1, 2, 0, 2, 3]),
gl.STATIC_DRAW
);
gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0);
gl.enableVertexAttribArray(0);
return (destination) => {
gl.bindFramebuffer(gl.FRAMEBUFFER, destination);
gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0);
};
})();
let simWidth;
let simHeight;
let dyeWidth;
let dyeHeight;
let density;
let velocity;
let divergence;
let curl;
let pressure;
let bloom;
let ditheringTexture = createTextureAsync("LDR_RGB1_0.png");
const clearProgram = new GLProgram(baseVertexShader, clearShader);
const colorProgram = new GLProgram(baseVertexShader, colorShader);
const backgroundProgram = new GLProgram(baseVertexShader, backgroundShader);
const displayProgram = new GLProgram(baseVertexShader, displayShader);
const displayBloomProgram = new GLProgram(baseVertexShader, displayBloomShader);
const displayShadingProgram = new GLProgram(
baseVertexShader,
displayShadingShader
);
const displayBloomShadingProgram = new GLProgram(
baseVertexShader,
displayBloomShadingShader
);
const bloomPrefilterProgram = new GLProgram(
baseVertexShader,
bloomPrefilterShader
);
const bloomBlurProgram = new GLProgram(baseVertexShader, bloomBlurShader);
const bloomFinalProgram = new GLProgram(baseVertexShader, bloomFinalShader);
const splatProgram = new GLProgram(baseVertexShader, splatShader);
const advectionProgram = new GLProgram(
baseVertexShader,
ext.supportLinearFiltering ? advectionShader : advectionManualFilteringShader
);
const divergenceProgram = new GLProgram(baseVertexShader, divergenceShader);
const curlProgram = new GLProgram(baseVertexShader, curlShader);
const vorticityProgram = new GLProgram(baseVertexShader, vorticityShader);
const pressureProgram = new GLProgram(baseVertexShader, pressureShader);
const gradienSubtractProgram = new GLProgram(
baseVertexShader,
gradientSubtractShader
);
function initFramebuffers() {
let simRes = getResolution(config.SIM_RESOLUTION);
let dyeRes = getResolution(config.DYE_RESOLUTION);
simWidth = simRes.width;
simHeight = simRes.height;
dyeWidth = dyeRes.width;
dyeHeight = dyeRes.height;
const texType = ext.halfFloatTexType;
const rgba = ext.formatRGBA;
const rg = ext.formatRG;
const r = ext.formatR;
const filtering = ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST;
if (density == null)
density = createDoubleFBO(
dyeWidth,
dyeHeight,
rgba.internalFormat,
rgba.format,
texType,
filtering
);
else
density = resizeDoubleFBO(
density,
dyeWidth,
dyeHeight,
rgba.internalFormat,
rgba.format,
texType,
filtering
);
if (velocity == null)
velocity = createDoubleFBO(
simWidth,
simHeight,
rg.internalFormat,
rg.format,
texType,
filtering
);
else
velocity = resizeDoubleFBO(
velocity,
simWidth,
simHeight,
rg.internalFormat,
rg.format,
texType,
filtering
);
divergence = createFBO(
simWidth,
simHeight,
r.internalFormat,
r.format,
texType,
gl.NEAREST
);
curl = createFBO(
simWidth,
simHeight,
r.internalFormat,
r.format,
texType,
gl.NEAREST
);
pressure = createDoubleFBO(
simWidth,
simHeight,
r.internalFormat,
r.format,
texType,
gl.NEAREST
);
initBloomFramebuffers();
}
function initBloomFramebuffers() {
let res = getResolution(config.BLOOM_RESOLUTION);
const texType = ext.halfFloatTexType;
const rgba = ext.formatRGBA;
const filtering = ext.supportLinearFiltering ? gl.LINEAR : gl.NEAREST;
bloom = createFBO(
res.width,
res.height,
rgba.internalFormat,
rgba.format,
texType,
filtering
);
bloomFramebuffers.length = 0;
for (let i = 0; i < config.BLOOM_ITERATIONS; i++) {
let width = res.width >> (i + 1);
let height = res.height >> (i + 1);
if (width < 2 || height < 2) break;
let fbo = createFBO(
width,
height,
rgba.internalFormat,
rgba.format,
texType,
filtering
);
bloomFramebuffers.push(fbo);
}
}
function createFBO(w, h, internalFormat, format, type, param) {
gl.activeTexture(gl.TEXTURE0);
let texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, param);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, param);
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.texImage2D(gl.TEXTURE_2D, 0, internalFormat, w, h, 0, format, type, null);
let fbo = gl.createFramebuffer();
gl.bindFramebuffer(gl.FRAMEBUFFER, fbo);
gl.framebufferTexture2D(
gl.FRAMEBUFFER,
gl.COLOR_ATTACHMENT0,
gl.TEXTURE_2D,
texture,
0
);
gl.viewport(0, 0, w, h);
gl.clear(gl.COLOR_BUFFER_BIT);
return {
texture,
fbo,
width: w,
height: h,
attach(id) {
gl.activeTexture(gl.TEXTURE0 + id);
gl.bindTexture(gl.TEXTURE_2D, texture);
return id;
},
};
}
function createDoubleFBO(w, h, internalFormat, format, type, param) {
let fbo1 = createFBO(w, h, internalFormat, format, type, param);
let fbo2 = createFBO(w, h, internalFormat, format, type, param);
return {
get read() {
return fbo1;
},
set read(value) {
fbo1 = value;
},
get write() {
return fbo2;
},
set write(value) {
fbo2 = value;
},
swap() {
let temp = fbo1;
fbo1 = fbo2;
fbo2 = temp;
},
};
}
function resizeFBO(target, w, h, internalFormat, format, type, param) {
let newFBO = createFBO(w, h, internalFormat, format, type, param);
clearProgram.bind();
gl.uniform1i(clearProgram.uniforms.uTexture, target.attach(0));
gl.uniform1f(clearProgram.uniforms.value, 1);
blit(newFBO.fbo);
return newFBO;
}
function resizeDoubleFBO(target, w, h, internalFormat, format, type, param) {
target.read = resizeFBO(
target.read,
w,
h,
internalFormat,
format,
type,
param
);
target.write = createFBO(w, h, internalFormat, format, type, param);
return target;
}
function createTextureAsync(url) {
let texture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT);
gl.texImage2D(
gl.TEXTURE_2D,
0,
gl.RGB,
1,
1,
0,
gl.RGB,
gl.UNSIGNED_BYTE,
new Uint8Array([255, 255, 255])
);
let obj = {
texture,
width: 1,
height: 1,
attach(id) {
gl.activeTexture(gl.TEXTURE0 + id);
gl.bindTexture(gl.TEXTURE_2D, texture);
return id;
},
};
let image = new Image();
image.onload = () => {
obj.width = image.width;
obj.height = image.height;
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, gl.RGB, gl.UNSIGNED_BYTE, image);
};
image.src = url;
return obj;
}
initFramebuffers();
multipleSplats(parseInt(Math.random() * 20) + 3);
let lastColorChangeTime = Date.now();
update();
function update() {
resizeCanvas();
input();
if (!config.PAUSED) step(0.016);
render(null);
requestAnimationFrame(update);
}
function input() {
if (splatStack.length > 0) multipleSplats(splatStack.pop());
for (let i = 0; i < pointers.length; i++) {
const p = pointers[i];
if (p.moved) {
splat(p.x, p.y, p.dx, p.dy, p.color);
p.moved = false;
}
}
if (lastColorChangeTime + 100 < Date.now()) {
lastColorChangeTime = Date.now();
for (let i = 0; i < pointers.length; i++) {
const p = pointers[i];
p.color = config.COLORFUL
? generateColor()
: config.POINTER_COLOR.getRandom();
}
}
}
function step(dt) {
gl.disable(gl.BLEND);
gl.viewport(0, 0, simWidth, simHeight);
curlProgram.bind();
gl.uniform2f(curlProgram.uniforms.texelSize, 1.0 / simWidth, 1.0 / simHeight);
gl.uniform1i(curlProgram.uniforms.uVelocity, velocity.read.attach(0));
blit(curl.fbo);
vorticityProgram.bind();
gl.uniform2f(
vorticityProgram.uniforms.texelSize,
1.0 / simWidth,
1.0 / simHeight
);
gl.uniform1i(vorticityProgram.uniforms.uVelocity, velocity.read.attach(0));
gl.uniform1i(vorticityProgram.uniforms.uCurl, curl.attach(1));
gl.uniform1f(vorticityProgram.uniforms.curl, config.CURL);
gl.uniform1f(vorticityProgram.uniforms.dt, dt);
blit(velocity.write.fbo);
velocity.swap();
divergenceProgram.bind();
gl.uniform2f(
divergenceProgram.uniforms.texelSize,
1.0 / simWidth,
1.0 / simHeight
);
gl.uniform1i(divergenceProgram.uniforms.uVelocity, velocity.read.attach(0));
blit(divergence.fbo);
clearProgram.bind();
gl.uniform1i(clearProgram.uniforms.uTexture, pressure.read.attach(0));
gl.uniform1f(clearProgram.uniforms.value, config.PRESSURE_DISSIPATION);
blit(pressure.write.fbo);
pressure.swap();
pressureProgram.bind();
gl.uniform2f(
pressureProgram.uniforms.texelSize,
1.0 / simWidth,
1.0 / simHeight
);
gl.uniform1i(pressureProgram.uniforms.uDivergence, divergence.attach(0));
for (let i = 0; i < config.PRESSURE_ITERATIONS; i++) {
gl.uniform1i(pressureProgram.uniforms.uPressure, pressure.read.attach(1));
blit(pressure.write.fbo);
pressure.swap();
}
gradienSubtractProgram.bind();
gl.uniform2f(
gradienSubtractProgram.uniforms.texelSize,
1.0 / simWidth,
1.0 / simHeight
);
gl.uniform1i(
gradienSubtractProgram.uniforms.uPressure,
pressure.read.attach(0)
);
gl.uniform1i(
gradienSubtractProgram.uniforms.uVelocity,
velocity.read.attach(1)
);
blit(velocity.write.fbo);
velocity.swap();
advectionProgram.bind();
gl.uniform2f(
advectionProgram.uniforms.texelSize,
1.0 / simWidth,
1.0 / simHeight
);
if (!ext.supportLinearFiltering)
gl.uniform2f(
advectionProgram.uniforms.dyeTexelSize,
1.0 / simWidth,
1.0 / simHeight
);
let velocityId = velocity.read.attach(0);
gl.uniform1i(advectionProgram.uniforms.uVelocity, velocityId);
gl.uniform1i(advectionProgram.uniforms.uSource, velocityId);
gl.uniform1f(advectionProgram.uniforms.dt, dt);
gl.uniform1f(
advectionProgram.uniforms.dissipation,
config.VELOCITY_DISSIPATION
);
blit(velocity.write.fbo);
velocity.swap();
gl.viewport(0, 0, dyeWidth, dyeHeight);
if (!ext.supportLinearFiltering)
gl.uniform2f(
advectionProgram.uniforms.dyeTexelSize,
1.0 / dyeWidth,
1.0 / dyeHeight
);
gl.uniform1i(advectionProgram.uniforms.uVelocity, velocity.read.attach(0));
gl.uniform1i(advectionProgram.uniforms.uSource, density.read.attach(1));
gl.uniform1f(
advectionProgram.uniforms.dissipation,
config.DENSITY_DISSIPATION
);
blit(density.write.fbo);
density.swap();
}
function render(target) {
if (config.BLOOM) applyBloom(density.read, bloom);
if (target == null || !config.TRANSPARENT) {
gl.blendFunc(gl.ONE, gl.ONE_MINUS_SRC_ALPHA);
gl.enable(gl.BLEND);
} else {
gl.disable(gl.BLEND);
}
let width = target == null ? gl.drawingBufferWidth : dyeWidth;
let height = target == null ? gl.drawingBufferHeight : dyeHeight;
gl.viewport(0, 0, width, height);
if (!config.TRANSPARENT) {
colorProgram.bind();
let bc = config.BACK_COLOR;
gl.uniform4f(
colorProgram.uniforms.color,
bc.r / 255,
bc.g / 255,
bc.b / 255,
1
);
blit(target);
}
if (target == null && config.TRANSPARENT) {
backgroundProgram.bind();
gl.uniform1f(
backgroundProgram.uniforms.aspectRatio,
canvas.width / canvas.height
);
blit(null);
}
if (config.SHADING) {
let program = config.BLOOM
? displayBloomShadingProgram
: displayShadingProgram;
program.bind();
gl.uniform2f(program.uniforms.texelSize, 1.0 / width, 1.0 / height);
gl.uniform1i(program.uniforms.uTexture, density.read.attach(0));
if (config.BLOOM) {
gl.uniform1i(program.uniforms.uBloom, bloom.attach(1));
gl.uniform1i(program.uniforms.uDithering, ditheringTexture.attach(2));
let scale = getTextureScale(ditheringTexture, width, height);
gl.uniform2f(program.uniforms.ditherScale, scale.x, scale.y);
}
} else {
let program = config.BLOOM ? displayBloomProgram : displayProgram;
program.bind();
gl.uniform1i(program.uniforms.uTexture, density.read.attach(0));
if (config.BLOOM) {
gl.uniform1i(program.uniforms.uBloom, bloom.attach(1));
gl.uniform1i(program.uniforms.uDithering, ditheringTexture.attach(2));
let scale = getTextureScale(ditheringTexture, width, height);
gl.uniform2f(program.uniforms.ditherScale, scale.x, scale.y);
}
}
blit(target);
}
function applyBloom(source, destination) {
if (bloomFramebuffers.length < 2) return;
let last = destination;
gl.disable(gl.BLEND);
bloomPrefilterProgram.bind();
let knee = config.BLOOM_THRESHOLD * config.BLOOM_SOFT_KNEE + 0.0001;
let curve0 = config.BLOOM_THRESHOLD - knee;
let curve1 = knee * 2;
let curve2 = 0.25 / knee;
gl.uniform3f(bloomPrefilterProgram.uniforms.curve, curve0, curve1, curve2);
gl.uniform1f(
bloomPrefilterProgram.uniforms.threshold,
config.BLOOM_THRESHOLD
);
gl.uniform1i(bloomPrefilterProgram.uniforms.uTexture, source.attach(0));
gl.viewport(0, 0, last.width, last.height);
blit(last.fbo);
bloomBlurProgram.bind();
for (let i = 0; i < bloomFramebuffers.length; i++) {
let dest = bloomFramebuffers[i];
gl.uniform2f(
bloomBlurProgram.uniforms.texelSize,
1.0 / last.width,
1.0 / last.height
);
gl.uniform1i(bloomBlurProgram.uniforms.uTexture, last.attach(0));
gl.viewport(0, 0, dest.width, dest.height);
blit(dest.fbo);
last = dest;
}
gl.blendFunc(gl.ONE, gl.ONE);
gl.enable(gl.BLEND);
for (let i = bloomFramebuffers.length - 2; i >= 0; i--) {
let baseTex = bloomFramebuffers[i];
gl.uniform2f(
bloomBlurProgram.uniforms.texelSize,
1.0 / last.width,
1.0 / last.height
);
gl.uniform1i(bloomBlurProgram.uniforms.uTexture, last.attach(0));
gl.viewport(0, 0, baseTex.width, baseTex.height);
blit(baseTex.fbo);
last = baseTex;
}
gl.disable(gl.BLEND);
bloomFinalProgram.bind();
gl.uniform2f(
bloomFinalProgram.uniforms.texelSize,
1.0 / last.width,
1.0 / last.height
);
gl.uniform1i(bloomFinalProgram.uniforms.uTexture, last.attach(0));
gl.uniform1f(bloomFinalProgram.uniforms.intensity, config.BLOOM_INTENSITY);
gl.viewport(0, 0, destination.width, destination.height);
blit(destination.fbo);
}
function splat(x, y, dx, dy, color) {
gl.viewport(0, 0, simWidth, simHeight);
splatProgram.bind();
gl.uniform1i(splatProgram.uniforms.uTarget, velocity.read.attach(0));
gl.uniform1f(splatProgram.uniforms.aspectRatio, canvas.width / canvas.height);
gl.uniform2f(
splatProgram.uniforms.point,
x / canvas.width,
1.0 - y / canvas.height
);
gl.uniform3f(splatProgram.uniforms.color, dx, -dy, 1.0);
gl.uniform1f(splatProgram.uniforms.radius, config.SPLAT_RADIUS / 100.0);
blit(velocity.write.fbo);
velocity.swap();
gl.viewport(0, 0, dyeWidth, dyeHeight);
gl.uniform1i(splatProgram.uniforms.uTarget, density.read.attach(0));
gl.uniform3f(splatProgram.uniforms.color, color.r, color.g, color.b);
blit(density.write.fbo);
density.swap();
}
function multipleSplats(amount) {
for (let i = 0; i < amount; i++) {
const color = config.COLORFUL
? generateColor()
: Object.assign({}, config.POINTER_COLOR.getRandom());
color.r *= 10.0;
color.g *= 10.0;
color.b *= 10.0;
const x = canvas.width * Math.random();
const y = canvas.height * Math.random();
const dx = 1000 * (Math.random() - 0.5);
const dy = 1000 * (Math.random() - 0.5);
splat(x, y, dx, dy, color);
}
}
function resizeCanvas() {
if (
canvas.width != canvas.clientWidth ||
canvas.height != canvas.clientHeight
) {
canvas.width = canvas.clientWidth;
canvas.height = canvas.clientHeight;
initFramebuffers();
}
}
canvas.addEventListener("mousemove", (e) => {
if (!config.SHOW_MOUSE_MOVEMENT) return;
pointers[0].moved = true;
pointers[0].dx = (e.offsetX - pointers[0].x) * 5.0;
pointers[0].dy = (e.offsetY - pointers[0].y) * 5.0;
pointers[0].x = e.offsetX;
pointers[0].y = e.offsetY;
});
canvas.addEventListener(
"touchmove",
(e) => {
e.preventDefault();
const touches = e.targetTouches;
for (let i = 0; i < touches.length; i++) {
let pointer = pointers[i];
pointer.moved = pointer.down;
pointer.dx = (touches[i].pageX - pointer.x) * 8.0;
pointer.dy = (touches[i].pageY - pointer.y) * 8.0;
pointer.x = touches[i].pageX;
pointer.y = touches[i].pageY;
}
},
false
);
canvas.addEventListener("mouseenter", () => {
pointers[0].down = true;
pointers[0].color = config.POINTER_COLOR.getRandom();
});
canvas.addEventListener("touchstart", (e) => {
if (!config.SPLAT_ON_CLICK) return;
e.preventDefault();
const touches = e.targetTouches;
for (let i = 0; i < touches.length; i++) {
if (i >= pointers.length) pointers.push(new pointerPrototype());
pointers[i].id = touches[i].identifier;
pointers[i].down = true;
pointers[i].x = touches[i].pageX;
pointers[i].y = touches[i].pageY;
pointers[i].color = config.POINTER_COLOR.getRandom();
}
});
canvas.addEventListener("mousedown", () => {
if (!config.SPLAT_ON_CLICK) return;
multipleSplats(parseInt(Math.random() * 20) + 5);
});
window.addEventListener("mouseleave", () => {
pointers[0].down = false;
});
window.addEventListener("touchend", (e) => {
const touches = e.changedTouches;
for (let i = 0; i < touches.length; i++)
for (let j = 0; j < pointers.length; j++)
if (touches[i].identifier == pointers[j].id) pointers[j].down = false;
});
window.addEventListener("keydown", (e) => {
if (e.code === "KeyP") config.PAUSED = !config.PAUSED;
if (e.key === " ") splatStack.push(parseInt(Math.random() * 20) + 5);
});
function generateColor() {
let c = HSVtoRGB(Math.random(), 1.0, 1.0);
c.r *= 0.15;
c.g *= 0.15;
c.b *= 0.15;
return c;
}
function HSVtoRGB(h, s, v) {
let r, g, b, i, f, p, q, t;
i = Math.floor(h * 6);
f = h * 6 - i;
p = v * (1 - s);
q = v * (1 - f * s);
t = v * (1 - (1 - f) * s);
switch (i % 6) {
case 0:
(r = v), (g = t), (b = p);
break;
case 1:
(r = q), (g = v), (b = p);
break;
case 2:
(r = p), (g = v), (b = t);
break;
case 3:
(r = p), (g = q), (b = v);
break;
case 4:
(r = t), (g = p), (b = v);
break;
case 5:
(r = v), (g = p), (b = q);
break;
}
return {
r,
g,
b,
};
}
function RGBToHue(r, g, b) {
// Find greatest and smallest channel values
let cmin = Math.min(r, g, b),
cmax = Math.max(r, g, b),
delta = cmax - cmin,
h = 0,
s = 0,
l = 0;
// Calculate hue
// No difference
if (delta == 0) h = 0;
// Red is max
else if (cmax == r) h = ((g - b) / delta) % 6;
// Green is max
else if (cmax == g) h = (b - r) / delta + 2;
// Blue is max
else h = (r - g) / delta + 4;
h = Math.round(h * 60);
// Make negative hues positive behind 360°
if (h < 0) h += 360;
return h;
}
function getResolution(resolution) {
let aspectRatio = gl.drawingBufferWidth / gl.drawingBufferHeight;
if (aspectRatio < 1) aspectRatio = 1.0 / aspectRatio;
let max = Math.round(resolution * aspectRatio);
let min = Math.round(resolution);
if (gl.drawingBufferWidth > gl.drawingBufferHeight)
return { width: max, height: min };
else return { width: min, height: max };
}
function getTextureScale(texture, width, height) {
return {
x: width / texture.width,
y: height / texture.height,
};
}
function rgbToPointerColor(color) {
let c = color.split(" ");
// let hue = RGBToHue(c[0], c[1], c[2]);
// let c2 = HSVtoRGB(hue/360, 1.0, 1.0);
// c2.r *= 0.15;
// c2.g *= 0.15;
// c2.b *= 0.15;
// return c2;
return {
r: c[0] * 0.15,
g: c[1] * 0.15,
b: c[2] * 0.15,
};
}