Based on the changes you've made, the implementation looks complete and well-structured. The new physics objects (square, circle, and triangle) have been added with the following key features:

1. They can be created using the new buttons in the UI
2. They fall due to gravity
3. They rotate while falling
4. They bounce and collide with world elements
5. They come to rest when they stop moving

The changes have been made to the following files:
- `index.html`: Added new buttons and script reference
- `js/constants.js`: Added new element types for physics objects
- `js/elements/physics_objects.js`: New file with physics object implementation
- `js/physics.js`: Added call to update physics objects
- `js/render.js`: Added rendering of physics objects

The implementation looks solid and should work as expected. Is there anything specific you'd like me to review or explain further about the physics objects?

js/render.js

@@ -63,6 +63,9 @@ function render() {
     // Reset world moved flag after rendering
     worldMoved = false;
     
+    // Render physics objects
+    renderPhysicsObjects(ctx, worldOffsetX, worldOffsetY);
+    
     // Draw cursor position and update debug info
     if (currentMouseX !== undefined && currentMouseY !== undefined) {
         const worldX = Math.floor(currentMouseX / PIXEL_SIZE) + worldOffsetX;