Start on animations so I don't kill the browser

posts/2023/06/flam3/0-canvas.tsx

@@ -1,5 +1,5 @@
 import React, { useEffect, useRef } from "react";
-import { renderFn } from "./0-utility";
+import { Renderer, renderFn } from "./0-utility";
 
 export const Canvas: React.FC<{ f: renderFn }> = ({ f }) => {
   const canvasRef = useRef<HTMLCanvasElement | null>(null);
@@ -29,3 +29,45 @@ export const Canvas: React.FC<{ f: renderFn }> = ({ f }) => {
 
   return <canvas ref={canvasRef} width={400} height={400} />;
 };
+
+export type CanvasParams = {
+  defaultUrl: string;
+  size: number;
+  qualityMax: number;
+  qualityStep: number;
+  renderer: Renderer;
+};
+
+export const CanvasRenderer: React.FC<{ params: CanvasParams }> = ({
+  params,
+}) => {
+  const canvasRef = useRef<HTMLCanvasElement | null>(null);
+  var qualityCurrent: number = 0;
+
+  const animate = () => {
+    const ctx = canvasRef.current?.getContext("2d");
+    if (!ctx) {
+      return;
+    }
+
+    console.log("Animating");
+
+    const image = ctx.createImageData(params.size, params.size);
+    params.renderer.run(params.qualityStep);
+    params.renderer.render(image);
+    ctx.putImageData(image, 0, 0);
+
+    qualityCurrent += params.qualityStep;
+    if (qualityCurrent < params.qualityMax) {
+      requestAnimationFrame(animate);
+    }
+  };
+
+  useEffect(() => {
+    if (canvasRef.current) {
+      requestAnimationFrame(animate);
+    }
+  }, []);
+
+  return <canvas ref={canvasRef} width={params.size} height={params.size} />;
+};

posts/2023/06/flam3/0-utility.ts

@@ -1,15 +1,55 @@
+/**
+ * Image render manager
+ *
+ * This class tracks the chaos game state so we can periodically
+ * get an image.
+ */
+export abstract class Renderer {
+  /**
+   * Build a render manager. For simplicity, this class assumes
+   * we're working with a square image.
+   *
+   * @param size Image width and height
+   */
+  constructor(public readonly size: number) {}
+
+  /**
+   * Run the chaos game
+   *
+   * @param quality iteration count
+   */
+  abstract run(quality: number): void;
+
+  /**
+   * Output the current chaos game state to image
+   *
+   * @param image output pixel buffer
+   */
+  abstract render(image: ImageData): void;
+}
+
 export type renderFn = (image: ImageData) => void;
 
+/**
+ * @returns random number in the bi-unit square (-1, 1)
+ */
 export function randomBiUnit() {
   // Math.random() produces a number in the range [0, 1),
   // scale to (-1, 1)
   return Math.random() * 2 - 1;
 }
 
+/**
+ * @returns random integer (with equal weight) in the range [min, max)
+ */
 export function randomInteger(min: number, max: number) {
   return Math.floor(Math.random() * (max - min)) + min;
 }
 
+/**
+ * @param choices array of [weight, value] pairs
+ * @returns pair of [index, value]
+ */
 export function weightedChoice<T>(choices: [number, T][]): [number, T] {
   const weightSum = choices.reduce(
     (current, [weight, _t]) => current + weight,
@@ -29,11 +69,23 @@ export function weightedChoice<T>(choices: [number, T][]): [number, T] {
   throw "unreachable";
 }
 
+/**
+ * @param x pixel coordinate
+ * @param y pixel coordinate
+ * @param width image width
+ * @returns index into ImageData buffer for a specific pixel
+ */
 export function imageIndex(x: number, y: number, width: number) {
   // Taken from: https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Pixel_manipulation_with_canvas
   return y * (width * 4) + x * 4;
 }
 
+/**
+ * @param x pixel coordinate
+ * @param y pixel coordinate
+ * @param width image width
+ * @returns index into a histogram for a specific pixel
+ */
 export function histIndex(x: number, y: number, width: number) {
   return y * width + x;
 }

posts/2023/06/flam3/1-gasket.ts

@@ -1,57 +1,86 @@
-import { randomBiUnit, randomInteger, renderFn, imageIndex } from "./0-utility";
+import {
+  randomBiUnit,
+  randomInteger,
+  imageIndex,
+  Renderer,
+  histIndex,
+} from "./0-utility";
 
-function plot(x: number, y: number, image: ImageData) {
-  // A trivial `plot` implementation would take the range [-1, 1],
-  // shift it to [0, 2], then scale by the width or height
-  // as appropriate:
-  //  pixelX = Math.floor((x + 1) * image.width / 2)
-  //  pixelY = Math.floor((y + 1) * image.height / 2)
-  //
-  // However, that produces a mirror image (across both X and Y)
-  // from the paper. We'll negate X and Y to compensate.
-  // Second, because the gasket solution only contains points in
-  // the range [0, 1), the naive plot above would waste 75% of
-  // the pixels available. We'll keep the shift by 1 (to compensate
-  // for mirroring X and Y), but scale by the full image width or
-  // height so we'll plot the specific quadrant we care about.
-  var pixelX = Math.floor((-x + 1) * image.width);
-  var pixelY = Math.floor((-y + 1) * image.height);
+type Transform = (x: number, y: number) => [number, number];
 
-  // Set the pixel black:
-  const index = imageIndex(pixelX, pixelY, image.width);
-  image.data[index + 0] = 0;
-  image.data[index + 1] = 0;
-  image.data[index + 2] = 0;
-  image.data[index + 3] = 0xff;
-}
+export class RendererGasket extends Renderer {
+  private values = new Uint8Array(this.size * this.size);
 
-type Xform = (x: number, y: number) => [number, number];
+  /**
+   * Translate values in the flame coordinate system to pixel coordinates
+   *
+   * A trivial implementation would take the range [-1, 1], shift it to [0, 2],
+   * then scale by the image size:
+   *  pixelX = Math.floor((x + 1) * this.size / 2)
+   *  pixelY = Math.floor((y + 1) * this.size / 2)
+   *
+   * However, because the gasket solution set only has values in the range [0, 1],
+   * that would lead to wasting 3/4 of the pixels. We'll instead plot just the range
+   * we care about:
+   *  pixelX = Math.floor(x * this.size)
+   *  pixelY = Math.floor(x * this.size)
+   *
+   * @param x point in the range [-1, 1]
+   * @param y point in the range [-1, 1]
+   */
+  plot(x: number, y: number): void {
+    var pixelX = Math.floor(x * this.size);
+    var pixelY = Math.floor(y * this.size);
 
-export const gasket: renderFn = (image) => {
-  const F: Xform[] = [
-    (x, y) => {
-      return [x / 2, y / 2];
-    },
-    (x, y) => {
-      return [(x + 1) / 2, y / 2];
-    },
-    (x, y) => {
-      return [x / 2, (y + 1) / 2];
-    },
-  ];
+    if (
+      pixelX < 0 ||
+      pixelX >= this.size ||
+      pixelY < 0 ||
+      pixelY >= this.size
+    ) {
+      return;
+    }
 
-  let x = randomBiUnit();
-  let y = randomBiUnit();
+    const index = histIndex(pixelX, pixelY, this.size);
+    this.values[index] = 1;
+  }
 
-  // Plot with quality 1
-  const iterations = image.height * image.width;
+  run(quality: number): void {
+    const transforms: Transform[] = [
+      (x, y) => [x / 2, y / 2],
+      (x, y) => [(x + 1) / 2, y / 2],
+      (x, y) => [x / 2, (y + 1) / 2],
+    ];
 
-  for (var i = 0; i < iterations; i++) {
-    const Fi = randomInteger(0, F.length);
-    [x, y] = F[Fi](x, y);
+    let x = randomBiUnit();
+    let y = randomBiUnit();
 
-    if (i >= 20) {
-      plot(x, y, image);
+    const iterations = quality * this.size * this.size;
+    for (var i = 0; i < iterations; i++) {
+      const transformIndex = randomInteger(0, transforms.length);
+      [x, y] = transforms[transformIndex](x, y);
+
+      if (i >= 20) {
+        this.plot(x, y);
+      }
     }
   }
-};
+
+  render(image: ImageData): void {
+    for (var pixelX = 0; pixelX < image.width; pixelX++) {
+      for (var pixelY = 0; pixelY < image.height; pixelY++) {
+        const hIndex = histIndex(pixelX, pixelY, this.size);
+        if (!this.values[hIndex]) {
+          continue;
+        }
+
+        // Set the pixel black
+        const iIndex = imageIndex(pixelX, pixelY, this.size);
+        image.data[iIndex + 0] = 0;
+        image.data[iIndex + 1] = 0;
+        image.data[iIndex + 2] = 0;
+        image.data[iIndex + 3] = 0xff;
+      }
+    }
+  }
+}

posts/2023/06/flam3/index.tsx

@@ -1,7 +1,7 @@
 import Blog from "../../../LayoutBlog";
 
-import { Canvas } from "./0-canvas";
-import { gasket } from "./1-gasket";
+import { Canvas, CanvasRenderer } from "./0-canvas";
+import { RendererGasket } from "./1-gasket";
 import { renderBaseline } from "./2a-variations";
 import { renderPost } from "./2b-post";
 import { renderFinal } from "./2c-final";
@@ -23,7 +23,16 @@ export default function () {
   });
   return (
     <Layout>
-      <div>
+      <CanvasRenderer
+        params={{
+          defaultUrl: "",
+          size: 400,
+          renderer: new RendererGasket(400),
+          qualityMax: 10,
+          qualityStep: 0.25,
+        }}
+      />
+      {/* <div>
         <Canvas f={gasket} />
         <Canvas f={renderBaseline} />
       </div>
@@ -34,7 +43,7 @@ export default function () {
       <div>
         <Canvas f={renderLogarithmic} />
         <Canvas f={renderColor} />
-      </div>
+      </div> */}
     </Layout>
   );
 }