if the selection is cleared with this tool active, there is no way to switch to another tool than to re-select an object (by clicking it) because the tool buttons in the toolbar will have been disabled. The mouse-event happens after the selection is changed, so we need to keep track of what the selection was previously by monitoring the selection state.
The map created by the shader is not strictly a depth map; not only is the "depth" encoded in the rgb channels, but it is also a distance to the camera instead of a "scene depth".
This is the first draft of the Support Eraser tool. The plugin creates a cube mesh which has the `anti_overhang_mesh` decorator causing it to block the creation of support material for overhangs within its volume. This distinction is necessary to avoid confusing this behavior from actually erasing a _portion_ of a support structure.
Some (non-necessary) improvements could be made such as:
- Better graphical style
- Discussion of whether the cube should be able to pass through the build plate or not
- Possible improvements to the tool's icon
- Placing the cube at a cursor click location
