When dragging an object, hold Shift to limit to horizontal/vertical; hold Ctrl to clone. When creating a line-shaped object or dragging its endpoints, hold Shift to lock the angle or snap to 0°, 45°, 90°; hold Ctrl to rotate/scale about its center.

Hold Ctrl, click several control points (e.g. endpoints), then click empty space to group these points and create a handle. Drag the handle (or press arrow keys) to move the group; Shift+drag to limit to horizontal/vertical; Ctrl+drag to rotate, Ctrl+Shift+drag to scale. Drag the "+" to set rotation/scaling center. Click the handle and press Ctrl+D to duplicate the group; press Delete to ungroup.

Double-click or right-click the control point (e.g. endpoint) of the object, edit the (x,y) coordinates in pixels, then press Enter.

When an object is selected (by clicking it), press arrow keys to move; Ctrl+D to duplicate; Delete key to delete.

The suggested way is to go to Discussions or Issues on GitHub. If you do not use GitHub, you can also email us at ray-optics@phydemo.app.

Direct contributions are also welcome (see the contribution guide).