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/** |
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* Authoring contract: `vec4 render(vec2 uv, float t)`, with everything in |
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* PRELUDE in scope. `uv` is centered and normalized by the shorter axis, `t` is |
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* seconds already scaled by the speed token. The canvas is transparent, so a |
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* shader only paints what it wants over the page color. |
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*/ |
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|
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// The one shader the flow draws when a design names none. |
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export const DEFAULT_SHADER = `vec4 render(vec2 uv, float t) { |
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vec2 drift = vec2(sin(t * 0.26), cos(t * 0.26)); |
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float dist = length(uv - drift * 0.55); |
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float falloff = smoothstep(0.95 * u_scale, 0.0, dist); |
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return vec4(u_color1, falloff * 0.32 * u_intensity); |
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}`; |
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|
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const VERTEX = `#version 300 es |
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in vec2 a_position; |
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void main() { |
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gl_Position = vec4(a_position, 0.0, 1.0); |
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}`; |
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|
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export const PRELUDE = `#version 300 es |
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precision highp float; |
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|
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uniform vec2 u_resolution; |
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uniform vec2 u_offset; |
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uniform float u_time; |
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uniform float u_speed; |
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uniform float u_scale; |
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uniform float u_intensity; |
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uniform vec3 u_color1; |
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uniform vec3 u_color2; |
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uniform vec3 u_color3; |
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uniform sampler2D u_prev; |
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uniform float u_frame; |
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|
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out vec4 fragColor; |
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|
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vec2 screenUV() { |
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return gl_FragCoord.xy / u_resolution; |
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} |
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|
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// The frame before this one: alpha is the shader's state, so Intensity is |
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// applied on the way to the screen and not by the shader. |
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vec4 prev(vec2 at) { |
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return texture(u_prev, at); |
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} |
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|
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float hash21(vec2 p) { |
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p = fract(p * vec2(123.34, 456.21)); |
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p += dot(p, p + 45.32); |
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return fract(p.x * p.y); |
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} |
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|
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float noise(vec2 p) { |
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vec2 i = floor(p); |
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vec2 f = fract(p); |
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vec2 u = f * f * (3.0 - 2.0 * f); |
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return mix( |
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mix(hash21(i), hash21(i + vec2(1.0, 0.0)), u.x), |
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mix(hash21(i + vec2(0.0, 1.0)), hash21(i + vec2(1.0, 1.0)), u.x), |
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u.y |
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); |
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} |
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|
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float fbm(vec2 p) { |
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float total = 0.0; |
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float amplitude = 0.5; |
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for (int i = 0; i < 5; i++) { |
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total += noise(p) * amplitude; |
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p *= 2.0; |
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amplitude *= 0.5; |
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} |
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return total; |
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} |
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`; |
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|
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const MAIN = ` |
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void main() { |
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vec2 uv = (gl_FragCoord.xy - 0.5 * u_resolution) / min(u_resolution.x, u_resolution.y) - u_offset; |
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fragColor = render(uv, u_time * u_speed); |
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} |
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`; |
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|
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const UNIFORMS = [ |
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'u_resolution', |
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'u_offset', |
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'u_time', |
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'u_speed', |
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'u_scale', |
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'u_intensity', |
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'u_color1', |
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'u_color2', |
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'u_color3', |
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'u_prev', |
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'u_frame', |
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]; |
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|
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// A board held between frames runs at cell resolution, not at canvas resolution. |
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const BOARD_COLUMNS = 90; |
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|
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const COPY_FRAGMENT = `#version 300 es |
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precision highp float; |
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uniform sampler2D u_source; |
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uniform vec2 u_resolution; |
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uniform vec2 u_offset; |
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uniform float u_intensity; |
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out vec4 fragColor; |
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void main() { |
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fragColor = texture(u_source, gl_FragCoord.xy / u_resolution - u_offset) * vec4(1.0, 1.0, 1.0, u_intensity); |
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} |
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`; |
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|
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// Full resolution: at half, a point-sized detail upscales into a smudge. |
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const RENDER_SCALE = 1; |
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const MAX_FPS = 30; |
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// No static check proves a shader is cheap enough for a given GPU, so watch it run. |
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const SLOW_FRAME_MS = (1000 / MAX_FPS) * 4; |
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const SLOW_FRAME_LIMIT = 30; |
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|
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const compile = (gl, type, source) => { |
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const shader = gl.createShader(type); |
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gl.shaderSource(shader, source); |
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gl.compileShader(shader); |
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if (gl.getShaderParameter(shader, gl.COMPILE_STATUS)) return { shader }; |
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const log = gl.getShaderInfoLog(shader); |
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gl.deleteShader(shader); |
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return { error: log || 'Shader failed to compile.' }; |
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}; |
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|
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export const createShaderCanvas = (canvas) => { |
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const gl = canvas.getContext('webgl2', { |
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alpha: true, |
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antialias: false, |
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depth: false, |
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stencil: false, |
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premultipliedAlpha: false, |
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powerPreference: 'low-power', |
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}); |
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if (!gl) return null; |
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|
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const quad = gl.createBuffer(); |
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gl.bindBuffer(gl.ARRAY_BUFFER, quad); |
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gl.bufferData( |
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gl.ARRAY_BUFFER, |
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new Float32Array([-1, -1, 3, -1, -1, 3]), |
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gl.STATIC_DRAW, |
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); |
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|
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let program = null; |
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let locations = {}; |
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let board = null; |
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let copy = null; |
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let frames = 0; |
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let frame = null; |
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let lastDraw = 0; |
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let paused = false; |
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let still = false; |
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let slowFrames = 0; |
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const start = performance.now(); |
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let values = { |
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speed: 1, |
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scale: 1, |
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intensity: 1, |
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offset: [0, 0], |
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colors: [ |
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[1, 1, 1], |
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[1, 1, 1], |
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[1, 1, 1], |
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], |
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}; |
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|
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const buildProgram = (fragmentSource) => { |
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const vertex = compile(gl, gl.VERTEX_SHADER, VERTEX); |
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const fragment = compile(gl, gl.FRAGMENT_SHADER, fragmentSource); |
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if (vertex.error || fragment.error) { |
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return { error: vertex.error || fragment.error }; |
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} |
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const next = gl.createProgram(); |
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gl.attachShader(next, vertex.shader); |
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gl.attachShader(next, fragment.shader); |
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gl.bindAttribLocation(next, 0, 'a_position'); |
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gl.linkProgram(next); |
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gl.deleteShader(vertex.shader); |
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gl.deleteShader(fragment.shader); |
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if (gl.getProgramParameter(next, gl.LINK_STATUS)) return { program: next }; |
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const log = gl.getProgramInfoLog(next); |
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gl.deleteProgram(next); |
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return { error: log || 'Shader failed to link.' }; |
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}; |
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|
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// Wrapped, so a shape leaving one edge of the board arrives at the other. |
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const makeSurface = (width, height) => { |
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const texture = gl.createTexture(); |
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gl.bindTexture(gl.TEXTURE_2D, texture); |
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gl.texImage2D( |
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gl.TEXTURE_2D, |
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0, |
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gl.RGBA, |
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width, |
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height, |
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0, |
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gl.RGBA, |
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gl.UNSIGNED_BYTE, |
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null, |
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); |
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST); |
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST); |
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT); |
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT); |
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const buffer = gl.createFramebuffer(); |
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gl.bindFramebuffer(gl.FRAMEBUFFER, buffer); |
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gl.framebufferTexture2D( |
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gl.FRAMEBUFFER, |
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gl.COLOR_ATTACHMENT0, |
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gl.TEXTURE_2D, |
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texture, |
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0, |
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); |
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gl.bindFramebuffer(gl.FRAMEBUFFER, null); |
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return { texture, buffer }; |
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}; |
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|
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const dropBoard = () => { |
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if (!board) return; |
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for (const surface of board.surfaces) { |
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gl.deleteTexture(surface.texture); |
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gl.deleteFramebuffer(surface.buffer); |
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} |
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board = null; |
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}; |
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|
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// Scale is the cell size, so changing it or the canvas starts the board over. |
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const ensureBoard = () => { |
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const columns = Math.round( |
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Math.min(260, Math.max(24, BOARD_COLUMNS * values.scale)), |
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); |
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const rows = Math.max( |
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1, |
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Math.round((columns * canvas.height) / Math.max(canvas.width, 1)), |
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); |
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if (board && board.width === columns && board.height === rows) return; |
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dropBoard(); |
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board = { |
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width: columns, |
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height: rows, |
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surfaces: [makeSurface(columns, rows), makeSurface(columns, rows)], |
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index: 0, |
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}; |
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frames = 0; |
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}; |
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|
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const resize = () => { |
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const dpr = Math.min(window.devicePixelRatio || 1, 2) * RENDER_SCALE; |
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const width = Math.max(1, Math.round(canvas.clientWidth * dpr)); |
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const height = Math.max(1, Math.round(canvas.clientHeight * dpr)); |
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if (canvas.width === width && canvas.height === height) return; |
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canvas.width = width; |
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canvas.height = height; |
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gl.viewport(0, 0, width, height); |
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}; |
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|
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const setUniforms = (width, height) => { |
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gl.uniform2f(locations.u_resolution, width, height); |
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gl.uniform1f( |
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locations.u_time, |
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still ? 0 : (performance.now() - start) / 1000, |
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); |
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gl.uniform1f(locations.u_speed, values.speed); |
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gl.uniform1f(locations.u_scale, values.scale); |
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gl.uniform1f(locations.u_intensity, values.intensity); |
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gl.uniform2f(locations.u_offset, values.offset[0], values.offset[1]); |
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gl.uniform3fv(locations.u_color1, values.colors[0]); |
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gl.uniform3fv(locations.u_color2, values.colors[1]); |
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gl.uniform3fv(locations.u_color3, values.colors[2]); |
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gl.uniform1f(locations.u_frame, frames); |
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}; |
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|
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// Intensity lands on the copy: the shader spends its alpha carrying state. |
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const drawBoard = () => { |
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ensureBoard(); |
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const read = board.surfaces[board.index]; |
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const write = board.surfaces[1 - board.index]; |
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|
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gl.bindFramebuffer(gl.FRAMEBUFFER, write.buffer); |
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gl.viewport(0, 0, board.width, board.height); |
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// biome-ignore lint/correctness/useHookAtTopLevel: WebGL, not a React hook. |
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gl.useProgram(program); |
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setUniforms(board.width, board.height); |
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gl.activeTexture(gl.TEXTURE0); |
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gl.bindTexture(gl.TEXTURE_2D, read.texture); |
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gl.uniform1i(locations.u_prev, 0); |
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gl.drawArrays(gl.TRIANGLES, 0, 3); |
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|
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gl.bindFramebuffer(gl.FRAMEBUFFER, null); |
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gl.viewport(0, 0, canvas.width, canvas.height); |
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gl.clearColor(0, 0, 0, 0); |
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gl.clear(gl.COLOR_BUFFER_BIT); |
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// biome-ignore lint/correctness/useHookAtTopLevel: WebGL, not a React hook. |
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gl.useProgram(copy.program); |
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gl.uniform2f(copy.resolution, canvas.width, canvas.height); |
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gl.uniform2f(copy.offset, values.offset[0], values.offset[1]); |
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gl.uniform1f(copy.intensity, values.intensity); |
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gl.activeTexture(gl.TEXTURE0); |
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gl.bindTexture(gl.TEXTURE_2D, write.texture); |
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gl.uniform1i(copy.source, 0); |
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gl.drawArrays(gl.TRIANGLES, 0, 3); |
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|
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board.index = 1 - board.index; |
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frames += 1; |
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}; |
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|
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const draw = () => { |
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if (!program) return; |
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resize(); |
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if (copy) { |
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drawBoard(); |
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return; |
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} |
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gl.clearColor(0, 0, 0, 0); |
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gl.clear(gl.COLOR_BUFFER_BIT); |
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// biome-ignore lint/correctness/useHookAtTopLevel: WebGL, not a React hook. |
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gl.useProgram(program); |
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setUniforms(canvas.width, canvas.height); |
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gl.drawArrays(gl.TRIANGLES, 0, 3); |
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frames += 1; |
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}; |
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|
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const loop = (now) => { |
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frame = requestAnimationFrame(loop); |
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if (paused || still) return; |
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if (now - lastDraw < 1000 / MAX_FPS) return; |
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// First frame has no interval to measure, and would read as a stall. |
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const elapsed = lastDraw ? now - lastDraw : 0; |
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lastDraw = now; |
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draw(); |
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|
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slowFrames = elapsed > SLOW_FRAME_MS ? slowFrames + 1 : 0; |
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if (slowFrames < SLOW_FRAME_LIMIT) return; |
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// Freezing keeps the look the partner chose; an error would reach nobody. |
| 341 |
still = true; |
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}; |
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|
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const ensureCopy = () => { |
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if (copy) return true; |
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const built = buildProgram(COPY_FRAGMENT); |
| 347 |
if (built.error) return false; |
| 348 |
copy = { |
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program: built.program, |
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source: gl.getUniformLocation(built.program, 'u_source'), |
| 351 |
resolution: gl.getUniformLocation(built.program, 'u_resolution'), |
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offset: gl.getUniformLocation(built.program, 'u_offset'), |
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intensity: gl.getUniformLocation(built.program, 'u_intensity'), |
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}; |
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return true; |
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}; |
| 357 |
|
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const dropCopy = () => { |
| 359 |
if (!copy) return; |
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gl.deleteProgram(copy.program); |
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copy = null; |
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dropBoard(); |
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}; |
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|
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const setSource = (body) => { |
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const built = buildProgram(PRELUDE + body + MAIN); |
| 367 |
if (built.error) return false; |
| 368 |
|
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// Only a shader that reads the frame before pays for the second pass. |
| 370 |
const held = /\bprev\s*\(/.test(body); |
| 371 |
if (held && !ensureCopy()) { |
| 372 |
gl.deleteProgram(built.program); |
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return false; |
| 374 |
} |
| 375 |
if (!held) dropCopy(); |
| 376 |
|
| 377 |
if (program) gl.deleteProgram(program); |
| 378 |
program = built.program; |
| 379 |
frames = 0; |
| 380 |
locations = Object.fromEntries( |
| 381 |
UNIFORMS.map((name) => [name, gl.getUniformLocation(program, name)]), |
| 382 |
); |
| 383 |
// biome-ignore lint/correctness/useHookAtTopLevel: WebGL, not a React hook. |
| 384 |
gl.useProgram(program); |
| 385 |
gl.enableVertexAttribArray(0); |
| 386 |
gl.bindBuffer(gl.ARRAY_BUFFER, quad); |
| 387 |
gl.vertexAttribPointer(0, 2, gl.FLOAT, false, 0, 0); |
| 388 |
slowFrames = 0; |
| 389 |
draw(); |
| 390 |
return true; |
| 391 |
}; |
| 392 |
|
| 393 |
const setValues = (next) => { |
| 394 |
values = { ...values, ...next }; |
| 395 |
if (still || paused) draw(); |
| 396 |
}; |
| 397 |
|
| 398 |
// Reduced motion gets one frame rather than a blank background. |
| 399 |
const setStill = (value) => { |
| 400 |
still = value; |
| 401 |
if (value) draw(); |
| 402 |
}; |
| 403 |
|
| 404 |
const controller = new AbortController(); |
| 405 |
const { signal } = controller; |
| 406 |
document.addEventListener( |
| 407 |
'visibilitychange', |
| 408 |
() => { |
| 409 |
paused = document.hidden; |
| 410 |
}, |
| 411 |
{ signal }, |
| 412 |
); |
| 413 |
canvas.addEventListener( |
| 414 |
'webglcontextlost', |
| 415 |
(event) => { |
| 416 |
event.preventDefault(); |
| 417 |
paused = true; |
| 418 |
}, |
| 419 |
{ signal }, |
| 420 |
); |
| 421 |
|
| 422 |
frame = requestAnimationFrame(loop); |
| 423 |
|
| 424 |
return { |
| 425 |
setSource, |
| 426 |
setValues, |
| 427 |
setStill, |
| 428 |
destroy() { |
| 429 |
controller.abort(); |
| 430 |
if (frame) cancelAnimationFrame(frame); |
| 431 |
if (program) gl.deleteProgram(program); |
| 432 |
dropCopy(); |
| 433 |
gl.deleteBuffer(quad); |
| 434 |
gl.getExtension('WEBGL_lose_context')?.loseContext(); |
| 435 |
}, |
| 436 |
}; |
| 437 |
}; |
| 438 |
|
