random spirals

anatol-grabowski · Jan 19, 2025 · 7b635af · 7b635af
1 parent 3b3d702
commit 7b635af
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Showing 2 changed files with 69 additions and 14 deletions.
diff --git a/capture/capture.html b/capture/capture.html
@@ -133,7 +133,11 @@
 
     // Generate a random path
     function generatePath() {
-      path = spiral(10, 10, canvas.width-10, canvas.height-10, 15, 10, 1, 'clockwise').map(([x, y]) => ({ x, y}))
+        const corner = Math.floor(Math.random() * 4)
+        const direction = Math.floor(Math.random() * 2)
+        const steps = Math.floor(Math.random() * 10)
+      path = spiral(10, 10, canvas.width-10, canvas.height-10, 10+steps, 5+steps, corner, direction)
+        .map(([x, y]) => ({ x, y}))
       crosshairIndex = 0;
       drawFrame();
     }

diff --git a/capture/spiral.js b/capture/spiral.js
@@ -1,47 +1,96 @@
-
-function spiral(xmin, ymin, xmax, ymax, xsteps, ysteps) {
+function spiral(xmin, ymin, xmax, ymax, xsteps, ysteps, startCorner = 0, direction = 0) {
     const pointsList = [];
-    let x = 0, y = 0;
+    let x, y;
+    let dir;
     const numPoints = (xsteps + 1) * (ysteps + 1);
-    let dir = 'right';
     let x0 = 0, y0 = 0, x1 = xsteps, y1 = ysteps;
+    startCorner = {
+        0: 'top-left',
+        1: 'top-right',
+        2: 'bottom-right',
+        3: 'bottom-left',
+    }[startCorner]
+
+    // Determine initial position and direction based on starting corner and direction
+    switch (startCorner) {
+        case 'top-left':
+            x = 0;
+            y = 0;
+            dir = direction === 0 ? 'right' : 'down';
+            break;
+        case 'top-right':
+            x = xsteps;
+            y = 0;
+            dir = direction === 0 ? 'down' : 'left';
+            break;
+        case 'bottom-right':
+            x = xsteps;
+            y = ysteps;
+            dir = direction === 0 ? 'left' : 'up';
+            break;
+        case 'bottom-left':
+            x = 0;
+            y = ysteps;
+            dir = direction === 0 ? 'up' : 'right';
+            break;
+        default:
+            throw new Error('Invalid startCorner. Must be "top-left", "top-right", "bottom-left", or "bottom-right".');
+    }
 
+    // Generate the spiral
     while (pointsList.length < numPoints) {
         pointsList.push([x, y]);
         if (dir === 'right') {
             x += 1;
             if (x === x1) {
-                y0 += 1;
-                dir = 'down';
+                if (direction === 0) {
+                    y0 += 1; // Update bounds clockwise
+                } else {
+                    y1 -= 1; // Update bounds counterclockwise
+                }
+                dir = direction === 0 ? 'down' : 'up';
             }
             continue;
         }
         if (dir === 'down') {
             y += 1;
             if (y === y1) {
-                x1 -= 1;
-                dir = 'left';
+                if (direction === 0) {
+                    x1 -= 1; // Update bounds clockwise
+                } else {
+                    x0 += 1; // Update bounds counterclockwise
+                }
+                dir = direction === 0 ? 'left' : 'right';
             }
             continue;
         }
         if (dir === 'left') {
             x -= 1;
             if (x === x0) {
-                y1 -= 1;
-                dir = 'up';
+                if (direction === 0) {
+                    y1 -= 1; // Update bounds clockwise
+                } else {
+                    y0 += 1; // Update bounds counterclockwise
+                }
+                dir = direction === 0 ? 'up' : 'down';
             }
             continue;
         }
         if (dir === 'up') {
             y -= 1;
             if (y === y0) {
-                x0 += 1;
-                dir = 'right';
+                if (direction === 0) {
+                    x0 += 1; // Update bounds clockwise
+                } else {
+                    x1 -= 1; // Update bounds counterclockwise
+                }
+                dir = direction === 0 ? 'right' : 'left';
             }
             continue;
         }
     }
 
+    // Scale points to the given xmin, ymin, xmax, ymax
     const dx = (xmax - xmin) / xsteps;
     const dy = (ymax - ymin) / ysteps;
     const points = pointsList.map(([px, py]) => [
@@ -52,4 +101,6 @@ function spiral(xmin, ymin, xmax, ymax, xsteps, ysteps) {
     return points;
 }
 
-window.spiral = spiral
+// Example usage:
+window.spiral = spiral;
+