Code for 2D camera system

blog/2024-11-15-playing-with-fire/4-camera/camera.ts

@@ -0,0 +1,38 @@
+export function camera(
+    x: number,
+    y: number,
+    width: number,
+    height: number,
+    scale: number,
+    zoom: number,
+    rotate: number,
+    offsetX: number,
+    offsetY: number,
+): [number, number] {
+    const zoomFactor = Math.pow(2, zoom);
+
+    // Zoom, offset, and rotation are
+    // applied in IFS coordinates
+    [x, y] = [
+        (x - offsetX) * zoomFactor,
+        (y - offsetY) * zoomFactor,
+    ];
+
+    [x, y] = [
+        x * Math.cos(rotate) -
+        y * Math.sin(rotate),
+        x * Math.sin(rotate) +
+        y * Math.cos(rotate),
+    ]
+
+    // Scale is applied to pixel
+    // coordinates. Shift by half
+    // the image width and height
+    // to compensate for the
+    // IFS coordinates being symmetric
+    // around the origin
+    return [
+        Math.floor(x * scale + width / 2),
+        Math.floor(y * scale + height / 2)
+    ];
+}