567 lines
18 KiB
TypeScript
567 lines
18 KiB
TypeScript
import { frag, vert } from './common/tags.ts';
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import { WebGLUtils } from './common/webgl.ts';
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import type { FolkShape } from './folk-shape.ts';
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/**
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* The DistanceField class calculates a distance field using the Jump Flooding Algorithm (JFA) in WebGL.
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* It renders shapes as seed points and computes the distance from each pixel to the nearest seed point.
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* Previous CPU-based implementation: github.com/folk-canvas/folk-canvas/commit/fdd7fb9d84d93ad665875cad25783c232fd17bcc
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*/
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export class DistanceField extends HTMLElement {
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static tagName = 'distance-field';
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private textures: WebGLTexture[] = [];
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private shapes!: NodeListOf<FolkShape>;
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private canvas!: HTMLCanvasElement;
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private glContext!: WebGL2RenderingContext;
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private framebuffer!: WebGLFramebuffer;
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private fullscreenQuadVAO!: WebGLVertexArrayObject;
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private shapeVAO!: WebGLVertexArrayObject;
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private jfaProgram!: WebGLProgram; // Shader program for the Jump Flooding Algorithm
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private renderProgram!: WebGLProgram; // Shader program for final rendering
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private seedProgram!: WebGLProgram; // Shader program for rendering seed points
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private static readonly MAX_DISTANCE = 99999.0;
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private positionBuffer: WebGLBuffer | null = null;
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private isPingTexture: boolean = true;
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static define() {
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customElements.define(this.tagName, this);
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}
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connectedCallback() {
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this.shapes = document.querySelectorAll('folk-shape');
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this.initWebGL();
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this.initShaders();
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this.initPingPongTextures();
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this.initSeedPointRendering();
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window.addEventListener('resize', this.handleResize);
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this.shapes.forEach((geometry) => {
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geometry.addEventListener('move', this.handleGeometryUpdate);
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geometry.addEventListener('resize', this.handleGeometryUpdate);
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});
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}
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disconnectedCallback() {
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window.removeEventListener('resize', this.handleResize);
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this.shapes.forEach((geometry) => {
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geometry.removeEventListener('move', this.handleGeometryUpdate);
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geometry.removeEventListener('resize', this.handleGeometryUpdate);
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});
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this.cleanupWebGLResources();
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}
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private initWebGL() {
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const { gl, canvas } = WebGLUtils.createWebGLCanvas(this.clientWidth, this.clientHeight, this);
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if (!gl || !canvas) {
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throw new Error('Failed to initialize WebGL context.');
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}
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this.canvas = canvas;
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this.glContext = gl;
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}
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/**
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* Handles updates to geometry elements by re-initializing seed points and rerunning the JFA.
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*/
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private handleGeometryUpdate = () => {
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this.initSeedPointRendering();
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this.runJumpFloodingAlgorithm();
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};
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/**
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* Initializes all shader programs used in rendering.
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*/
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private initShaders() {
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this.jfaProgram = WebGLUtils.createShaderProgram(this.glContext, commonVertShader, jfaFragShader);
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this.renderProgram = WebGLUtils.createShaderProgram(this.glContext, commonVertShader, renderFragShader);
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this.seedProgram = WebGLUtils.createShaderProgram(this.glContext, seedVertShader, seedFragShader);
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}
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/**
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* Initializes textures and framebuffer for ping-pong rendering.
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* Ping-pong textures are used to alternate between reading and writing textures in multi-pass algorithms.
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*/
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private initPingPongTextures() {
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const gl = this.glContext;
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const width = this.canvas.width;
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const height = this.canvas.height;
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// Delete existing textures to prevent memory leaks
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for (const texture of this.textures) {
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gl.deleteTexture(texture);
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}
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this.textures = [];
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// Enable the EXT_color_buffer_half_float extension for high-precision floating-point textures
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const ext = gl.getExtension('EXT_color_buffer_half_float');
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if (!ext) {
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console.error('EXT_color_buffer_half_float extension is not supported.');
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return;
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}
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// Create two textures for ping-pong rendering
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for (let i = 0; i < 2; i++) {
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const texture = gl.createTexture()!;
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gl.bindTexture(gl.TEXTURE_2D, texture);
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// Set texture parameters
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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.CLAMP_TO_EDGE);
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
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// Use high-precision format for accurate distance calculations
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gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA16F, width, height, 0, gl.RGBA, gl.HALF_FLOAT, null);
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this.textures.push(texture);
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}
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// Create or reuse the framebuffer
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if (!this.framebuffer) {
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this.framebuffer = gl.createFramebuffer()!;
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}
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// Check if framebuffer is complete
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const status = gl.checkFramebufferStatus(gl.FRAMEBUFFER);
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if (status !== gl.FRAMEBUFFER_COMPLETE) {
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console.error('Framebuffer is not complete:', status);
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return;
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}
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}
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/**
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* Initializes rendering of seed points (shapes) into a texture.
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* Seed points are the starting locations for distance calculations.
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*/
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private initSeedPointRendering() {
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const gl = this.glContext;
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const positions: number[] = [];
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const windowWidth = window.innerWidth;
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const windowHeight = window.innerHeight;
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// Collect positions and assign unique IDs to all shapes
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this.shapes.forEach((geometry, index) => {
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const rect = geometry.getClientRect();
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// Convert DOM coordinates to Normalized Device Coordinates (NDC)
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const x1 = (rect.left / windowWidth) * 2 - 1;
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const y1 = -((rect.top / windowHeight) * 2 - 1);
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const x2 = (rect.right / windowWidth) * 2 - 1;
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const y2 = -((rect.bottom / windowHeight) * 2 - 1);
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const shapeID = index + 1; // Avoid zero to prevent hash function issues
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// Represent each rectangle as two triangles, including shapeID as the z component
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positions.push(
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x1,
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y1,
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shapeID,
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x2,
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y1,
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shapeID,
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x1,
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y2,
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shapeID,
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x1,
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y2,
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shapeID,
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x2,
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y1,
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shapeID,
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x2,
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y2,
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shapeID
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);
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});
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if (!this.shapeVAO) {
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this.shapeVAO = gl.createVertexArray()!;
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gl.bindVertexArray(this.shapeVAO);
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this.positionBuffer = gl.createBuffer()!;
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gl.bindBuffer(gl.ARRAY_BUFFER, this.positionBuffer);
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gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.DYNAMIC_DRAW);
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const positionLocation = gl.getAttribLocation(this.seedProgram, 'a_position');
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gl.enableVertexAttribArray(positionLocation);
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gl.vertexAttribPointer(positionLocation, 3, gl.FLOAT, false, 0, 0);
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gl.bindVertexArray(null);
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} else {
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gl.bindBuffer(gl.ARRAY_BUFFER, this.positionBuffer!);
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gl.bufferSubData(gl.ARRAY_BUFFER, 0, new Float32Array(positions));
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}
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// Render the seed points into the texture
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this.renderSeedPoints();
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}
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/**
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* Renders the seed points (shapes) into one of the ping-pong textures.
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* This serves as the initial state for the Jump Flooding Algorithm.
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*/
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private renderSeedPoints() {
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const gl = this.glContext;
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// Bind framebuffer to render to the seed texture
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const seedTexture = this.textures[this.isPingTexture ? 0 : 1];
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gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer);
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gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, seedTexture, 0);
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// Clear the texture with a large initial distance
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gl.viewport(0, 0, this.canvas.width, this.canvas.height);
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gl.clearColor(0.0, 0.0, 0.0, DistanceField.MAX_DISTANCE);
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gl.clear(gl.COLOR_BUFFER_BIT);
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// Use the seed shader program
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gl.useProgram(this.seedProgram);
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// Set the canvas size uniform
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const canvasSizeLocation = gl.getUniformLocation(this.seedProgram, 'u_canvasSize');
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gl.uniform2f(canvasSizeLocation, this.canvas.width, this.canvas.height);
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// Bind VAO and draw shapes
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gl.bindVertexArray(this.shapeVAO);
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gl.drawArrays(gl.TRIANGLES, 0, this.shapes.length * 6);
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// Unbind VAO and framebuffer
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gl.bindVertexArray(null);
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gl.bindFramebuffer(gl.FRAMEBUFFER, null);
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}
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/**
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* Executes the Jump Flooding Algorithm (JFA) to compute the distance field.
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* It progressively reduces step sizes to refine the distance calculations.
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*/
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private runJumpFloodingAlgorithm() {
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let stepSize = 1 << Math.floor(Math.log2(Math.max(this.canvas.width, this.canvas.height)));
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// Perform passes with decreasing step sizes
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for (; stepSize >= 1; stepSize >>= 1) {
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this.renderPass(stepSize);
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}
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// Render the final result to the screen
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this.renderToScreen();
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}
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/**
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* Performs a single pass of the Jump Flooding Algorithm with a given step size.
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* This involves sampling neighboring pixels at the current step size.
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* @param stepSize The current step size for this pass.
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*/
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private renderPass(stepSize: number) {
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const gl = this.glContext;
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// Swap textures for ping-pong rendering
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const inputTexture = this.isPingTexture ? this.textures[0] : this.textures[1];
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const outputTexture = this.isPingTexture ? this.textures[1] : this.textures[0];
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// Bind framebuffer to output texture
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gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer);
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gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, outputTexture, 0);
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// Use the JFA shader program
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gl.useProgram(this.jfaProgram);
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// Compute and set the offsets uniform for neighboring pixels
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const offsets = this.computeOffsets(stepSize);
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const offsetsLocation = gl.getUniformLocation(this.jfaProgram, 'u_offsets');
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gl.uniform2fv(offsetsLocation, offsets);
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// Bind input texture containing the previous step's results
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gl.activeTexture(gl.TEXTURE0);
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gl.bindTexture(gl.TEXTURE_2D, inputTexture);
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gl.uniform1i(gl.getUniformLocation(this.jfaProgram, 'u_previousTexture'), 0);
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// Draw a fullscreen quad to process all pixels
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this.drawFullscreenQuad();
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// Toggle the flag
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this.isPingTexture = !this.isPingTexture;
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}
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/**
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* Renders the final distance field to the screen using the render shader program.
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*/
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private renderToScreen() {
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const gl = this.glContext;
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// Unbind framebuffer to render directly to the canvas
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gl.bindFramebuffer(gl.FRAMEBUFFER, null);
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gl.viewport(0, 0, this.canvas.width, this.canvas.height);
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// Use the render shader program
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gl.useProgram(this.renderProgram);
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// Bind the final texture containing the computed distance field
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const finalTexture = this.textures[this.isPingTexture ? 0 : 1];
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gl.activeTexture(gl.TEXTURE0);
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gl.bindTexture(gl.TEXTURE_2D, finalTexture);
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gl.uniform1i(gl.getUniformLocation(this.renderProgram, 'u_texture'), 0);
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// Draw a fullscreen quad to display the result
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this.drawFullscreenQuad();
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}
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/**
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* Draws a fullscreen quad to cover the entire canvas.
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* This is used in shader passes where every pixel needs to be processed.
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*/
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private drawFullscreenQuad() {
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const gl = this.glContext;
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// Initialize the quad geometry if it hasn't been done yet
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if (!this.fullscreenQuadVAO) {
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this.initFullscreenQuad();
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}
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gl.bindVertexArray(this.fullscreenQuadVAO);
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gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
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gl.bindVertexArray(null);
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}
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/**
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* Initializes the geometry and buffers for the fullscreen quad.
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*/
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private initFullscreenQuad() {
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const gl = this.glContext;
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// Define positions for a quad covering the entire screen
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const positions = new Float32Array([-1, -1, 1, -1, -1, 1, 1, 1]);
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this.fullscreenQuadVAO = gl.createVertexArray()!;
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gl.bindVertexArray(this.fullscreenQuadVAO);
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const positionBuffer = gl.createBuffer()!;
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gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
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gl.bufferData(gl.ARRAY_BUFFER, positions, gl.STATIC_DRAW);
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const positionAttributeLocation = gl.getAttribLocation(this.jfaProgram, 'a_position');
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gl.enableVertexAttribArray(positionAttributeLocation);
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gl.vertexAttribPointer(
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positionAttributeLocation,
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2, // size (x, y)
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gl.FLOAT, // type
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false, // normalize
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0, // stride
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0 // offset
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);
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gl.bindVertexArray(null);
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}
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/**
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* Handles window resize events by updating canvas size, re-initializing textures and seed points,
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* and rerunning the Jump Flooding Algorithm.
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*/
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private handleResize = () => {
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const gl = this.glContext;
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// Update canvas size to match the window
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this.canvas.width = window.innerWidth;
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this.canvas.height = window.innerHeight;
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// Update the viewport
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gl.viewport(0, 0, this.canvas.width, this.canvas.height);
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// Re-initialize textures with the new dimensions
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this.initPingPongTextures();
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// Re-initialize seed point rendering to update positions
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this.initSeedPointRendering();
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// Rerun the Jump Flooding Algorithm with the new sizes
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this.runJumpFloodingAlgorithm();
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};
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/**
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* Computes the offsets to sample neighboring pixels based on the current step size.
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* These offsets are used in the JFA shader to determine where to look for potential nearer seed points.
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* @param stepSize The current step size for neighbor sampling.
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* @returns A Float32Array of offsets.
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*/
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private computeOffsets(stepSize: number): Float32Array {
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const aspectRatio = this.canvas.width / this.canvas.height;
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const offsets: number[] = [];
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for (let y = -1; y <= 1; y++) {
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for (let x = -1; x <= 1; x++) {
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// Adjust x offset by aspect ratio to maintain uniform distances
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offsets.push((x * stepSize * aspectRatio) / this.canvas.width, (y * stepSize) / this.canvas.height);
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}
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}
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return new Float32Array(offsets);
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}
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/**
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* Cleans up WebGL resources to prevent memory leaks.
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* This is called when the element is disconnected from the DOM.
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*/
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private cleanupWebGLResources() {
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const gl = this.glContext;
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// Delete textures
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this.textures.forEach((texture) => gl.deleteTexture(texture));
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this.textures = [];
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// Delete framebuffer
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if (this.framebuffer) {
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gl.deleteFramebuffer(this.framebuffer);
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}
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// Delete VAOs
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if (this.fullscreenQuadVAO) {
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gl.deleteVertexArray(this.fullscreenQuadVAO);
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}
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if (this.shapeVAO) {
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gl.deleteVertexArray(this.shapeVAO);
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}
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// Delete shader programs
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if (this.jfaProgram) {
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gl.deleteProgram(this.jfaProgram);
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}
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if (this.renderProgram) {
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gl.deleteProgram(this.renderProgram);
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}
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if (this.seedProgram) {
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gl.deleteProgram(this.seedProgram);
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}
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// Clear other references
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this.shapes = null!;
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}
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}
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/**
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* Vertex shader shared by multiple programs.
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* Transforms vertices to normalized device coordinates and passes texture coordinates to the fragment shader.
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*/
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const commonVertShader = vert`#version 300 es
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precision mediump float;
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in vec2 a_position;
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out vec2 v_texCoord;
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void main() {
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v_texCoord = a_position * 0.5 + 0.5; // Transform to [0, 1] range
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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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* Fragment shader for the Jump Flooding Algorithm.
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* Updates the nearest seed point and distance for each pixel by examining neighboring pixels.
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*/
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const jfaFragShader = frag`#version 300 es
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precision mediump float;
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precision mediump int;
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in vec2 v_texCoord;
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out vec4 outColor;
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uniform sampler2D u_previousTexture;
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uniform vec2 u_offsets[9];
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void main() {
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vec4 nearest = texture(u_previousTexture, v_texCoord);
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float minDist = nearest.a;
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float aspectRatio = float(textureSize(u_previousTexture, 0).x) / float(textureSize(u_previousTexture, 0).y);
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for (int i = 0; i < 9; ++i) {
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vec2 sampleCoord = v_texCoord + u_offsets[i];
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sampleCoord = clamp(sampleCoord, vec2(0.0), vec2(1.0));
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vec4 sampled = texture(u_previousTexture, sampleCoord);
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if (sampled.z == 0.0) {
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continue;
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}
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// Adjust x coordinate by aspect ratio when calculating distance
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vec2 adjustedCoord = vec2(v_texCoord.x * aspectRatio, v_texCoord.y);
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vec2 adjustedSampledCoord = vec2(sampled.x * aspectRatio, sampled.y);
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float dist = distance(adjustedSampledCoord, adjustedCoord);
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if (dist < minDist) {
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nearest = sampled;
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nearest.a = dist;
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minDist = dist;
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}
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}
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outColor = nearest;
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}`;
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/**
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* Fragment shader for rendering the final distance field.
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* Converts distances to colors for visualization.
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*/
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const renderFragShader = frag`#version 300 es
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precision mediump float;
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in vec2 v_texCoord;
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out vec4 outColor;
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uniform sampler2D u_texture;
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vec3 hsv2rgb(vec3 c) {
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vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
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vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
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return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
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}
|
|
|
|
void main() {
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|
vec4 texel = texture(u_texture, v_texCoord);
|
|
|
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// Extract shape ID and distance
|
|
float shapeID = texel.z;
|
|
float distance = texel.a;
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|
|
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float hue = fract(shapeID * 0.61803398875); // Golden ratio conjugate
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vec3 shapeColor = hsv2rgb(vec3(hue, 0.5, 0.95));
|
|
|
|
|
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// Visualize distance as intensity
|
|
float intensity = exp(-distance * 10.0);
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|
|
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outColor = vec4(shapeColor * intensity, 1.0);
|
|
}`;
|
|
|
|
/**
|
|
* Vertex shader for rendering seed points.
|
|
* Outputs the shape ID to the fragment shader.
|
|
*/
|
|
const seedVertShader = vert`#version 300 es
|
|
precision mediump float;
|
|
|
|
in vec3 a_position; // x, y position and shapeID as z
|
|
flat out float v_shapeID;
|
|
|
|
void main() {
|
|
gl_Position = vec4(a_position.xy, 0.0, 1.0);
|
|
v_shapeID = a_position.z; // Pass shape ID to fragment shader
|
|
}`;
|
|
|
|
/**
|
|
* Fragment shader for rendering seed points.
|
|
* Initializes the texture with seed point positions and shape IDs.
|
|
*/
|
|
const seedFragShader = frag`#version 300 es
|
|
precision mediump float;
|
|
|
|
flat in float v_shapeID;
|
|
uniform vec2 u_canvasSize;
|
|
|
|
out vec4 outColor;
|
|
|
|
void main() {
|
|
vec2 seedCoord = gl_FragCoord.xy / u_canvasSize;
|
|
outColor = vec4(seedCoord, v_shapeID, 0.0); // Seed coords (x, y), shape ID (z), initial distance (a)
|
|
}`;
|