Replace 3D billboard rendering with 2D screen-space overlays using
GetWorldToScreen() and DrawTexturePro() for constant visibility.
Changes:
- Rename render functions to *_screen_space suffix
- Use GetWorldToScreen() to transform 3D positions to screen coordinates
- Replace DrawBillboard/DrawBillboardPro() with DrawTexturePro() for 2D rendering
- Use constant pixel sizes (40px spacecraft, 20-60px markers)
- Add off-screen culling to skip rendering outside viewport
- Update render order: 3D scene first, then 2D overlays
- Update documentation to reflect screen-space approach
Benefits:
- Markers remain visible at all zoom levels (constant screen size)
- Simplified sizing with pixel values instead of world-space math
- Better performance with off-screen culling
- Clearer separation: 3D scene vs UI indicators
- Create ui_renderer.cpp/h with all raygui UI panel rendering functions
- Remove UI rendering code from renderer.cpp (421 lines moved)
- Remove UI state fields from RenderState, create separate UIState struct
- Remove raygui dependency from renderer module
- Update main.cpp to initialize UIState and call UI render functions
- Update documentation to reflect new module structure
- Improve separation of concerns between 3D rendering and UI overlays
cinnaboot