faster

src/distanceField/cpt.ts

@@ -1,51 +1,108 @@
 import type { Vector2 } from '../utils/Vector2.ts';
-import { findHullParabolas, transpose } from './utils.ts';
 
+/** Adapted from Felzenszwalb, P. F., & Huttenlocher, D. P. (2012). Distance Transforms of Sampled Functions. Theory of Computing, 8(1), 415–428. */
 export function computeCPT(
   sedt: Float32Array[],
   cpt: Vector2[][],
   xcoords: Float32Array[],
   ycoords: Float32Array[]
 ): Vector2[][] {
   const length = sedt.length;
+  const tempArray = new Float32Array(length);
+
+  // Pre-allocate hull arrays
+  const hullVertices: Vector2[] = [];
+  const hullIntersections: Vector2[] = [];
 
   for (let row = 0; row < length; row++) {
-    horizontalPass(sedt[row], xcoords[row]);
+    horizontalPass(sedt[row], xcoords[row], hullVertices, hullIntersections);
   }
 
-  transpose(sedt);
+  for (let i = 0; i < length; i++) {
+    for (let j = i + 1; j < length; j++) {
+      tempArray[0] = sedt[i][j];
+      sedt[i][j] = sedt[j][i];
+      sedt[j][i] = tempArray[0];
+    }
+  }
 
   for (let row = 0; row < length; row++) {
-    horizontalPass(sedt[row], ycoords[row]);
+    horizontalPass(sedt[row], ycoords[row], hullVertices, hullIntersections);
   }
 
-  for (let col = 0; col < length; col++) {
-    for (let row = 0; row < length; row++) {
-      const y = ycoords[col][row];
-      const x = xcoords[y][col];
-      cpt[row][col] = { x, y };
-    }
+  const len = length * length;
+  for (let i = 0; i < len; i++) {
+    const row = i % length;
+    const col = (i / length) | 0;
+    const y = ycoords[col][row];
+    const x = xcoords[y][col];
+    cpt[row][col].x = x;
+    cpt[row][col].y = y;
   }
 
   return cpt;
 }
 
-function horizontalPass(singleRow: Float32Array, indices: Float32Array) {
-  const hullVertices: Vector2[] = [];
-  const hullIntersections: Vector2[] = [];
+function horizontalPass(
+  singleRow: Float32Array,
+  indices: Float32Array,
+  hullVertices: Vector2[],
+  hullIntersections: Vector2[]
+) {
+  // Clear hull arrays before use
+  hullVertices.length = 0;
+  hullIntersections.length = 0;
+
   findHullParabolas(singleRow, hullVertices, hullIntersections);
   marchParabolas(singleRow, hullVertices, hullIntersections, indices);
 }
 
 function marchParabolas(row: Float32Array, verts: Vector2[], intersections: Vector2[], indices: Float32Array) {
   let k = 0;
+  const n = row.length;
+  const numVerts = verts.length;
 
-  for (let i = 0; i < row.length; i++) {
-    while (intersections[k + 1].x < i) {
+  for (let i = 0; i < n; i++) {
+    while (k < numVerts - 1 && intersections[k + 1].x < i) {
       k++;
     }
     const dx = i - verts[k].x;
     row[i] = dx * dx + verts[k].y;
     indices[i] = verts[k].x;
   }
 }
+
+function findHullParabolas(row: Float32Array, verts: Vector2[], intersections: Vector2[]) {
+  let k = 0;
+
+  verts[k] = { x: 0, y: row[0] };
+  intersections[k] = { x: -Infinity, y: 0 };
+  intersections[k + 1] = { x: Infinity, y: 0 };
+
+  const n = row.length;
+
+  for (let i = 1; i < n; i++) {
+    const s: Vector2 = { x: 0, y: 0 };
+    const qx = i;
+    const qy = row[i];
+    let p = verts[k];
+
+    // Calculate intersection
+    s.x = (qy + qx * qx - (p.y + p.x * p.x)) / (2 * (qx - p.x));
+
+    while (k > 0 && s.x <= intersections[k].x) {
+      k--;
+      p = verts[k];
+      s.x = (qy + qx * qx - (p.y + p.x * p.x)) / (2 * (qx - p.x));
+    }
+
+    k++;
+    verts[k] = { x: qx, y: qy };
+    intersections[k] = { x: s.x, y: 0 };
+    intersections[k + 1] = { x: Infinity, y: 0 };
+  }
+
+  // Adjust the length of verts and intersections arrays
+  verts.length = k + 1;
+  intersections.length = k + 2;
+}

src/distanceField/fields.ts

@@ -147,47 +147,6 @@ export class Fields {
     }
   }
 
-  private renderer(
-    pixelRenderer: (
-      distance: number,
-      closestX: number,
-      closestY: number,
-      shapeColor: number,
-      row: number,
-      col: number
-    ) => { r: number; g: number; b: number }
-  ): ImageData {
-    const imageData = new ImageData(this.resolution, this.resolution);
-    const data = imageData.data;
-    const resolution = this.resolution;
-
-    // Pre-cache arrays to avoid repeated property access
-    const edt = this.edt;
-    const cpt = this.cpt;
-    const colorField = this.colorField;
-
-    // Process pixels in a single loop
-    for (let i = 0; i < resolution * resolution; i++) {
-      const row = i % resolution;
-      const col = (i / resolution) | 0; // Faster integer division
-      const index = i * 4;
-
-      const distance = edt[row][col];
-      const { x: closestX, y: closestY } = cpt[row][col];
-      const shapeColor = colorField[closestX][closestY];
-
-      const color = pixelRenderer(distance, closestX, closestY, shapeColor, row, col);
-
-      // Direct array access is faster than property access
-      data[index] = color.r;
-      data[index + 1] = color.g;
-      data[index + 2] = color.b;
-      data[index + 3] = 255;
-    }
-
-    return imageData;
-  }
-
   public generateImageData(): ImageData {
     const imageData = new ImageData(this.resolution, this.resolution);
     const data = imageData.data;