todo.txt

General:
- Renaming property should update all the nodes that use that property.
Priority: 3, Difficulty: 3
- Add Vector4 class to allow specifying vec4 uniforms/attributes without using Color class.
Priority: 3, Difficulty: 3
- Previews for some shader nodes.
Priority: 3, Difficulty: 8
- Advanced control of OpenGL settings in shaders.
Priority: 2, Difficulty: 5
- Figure out why Gradient node is difficult to close (click on button).
Priority: 2, Difficulty: 6
- Allow rendering to named frame buffers.
Priority: 2, Difficulty: 7
- Pipeline transitions (i.e. between scenes).
Priority: 2, Difficulty: 8
- Disable/enable "Up" and "Dn" buttons for shader lists.
Priority: 1, Difficulty: 2
- Shortcut to create and connect a property, when clicking on node circle in graph.
Priority: 1, Difficulty: 4
- Stencil support.
Priority: 1, Difficulty: 7

Sprite shader:

Particle shader:
- Add support for line particles.
Priority: 2, Difficulty: 5

Model shader: