refactor: Improve convert_shadertoy.py to generate compile-ready code

Major improvements to reduce manual code changes after conversion:

**Scene vs Post-Process Detection:**
- Added --post-process flag (default: scene effect)
- Scene effects: Simple pattern like HeptagonEffect (no texture input)
- Post-process effects: Uses PostProcessEffect base class

**Generated Code Now Compiles As-Is:**
- Scene: Uses gpu_create_render_pass() helper
- Post-process: Uses create_post_process_pipeline() helper
- No manual Effect base class rewrites needed
- Correct shader bindings for each type

**Improved WGSL Conversion:**
- Better mainImage extraction and conversion
- Proper fragCoord -> p.xy mapping
- Handles iResolution/iTime -> uniforms automatically
- Fixed return statements (fragColor = ... -> return ...)
- Preserves helper functions from original shader

**Better Instructions:**
- Shows exact asset.txt format with SHADER_ prefix
- Includes shader declaration/definition steps
- Indicates correct test list (scene_effects vs post_process_effects)

**Example:**
```bash
./tools/shadertoy/convert_shadertoy.py shader.txt MyEffect
# Generates compile-ready scene effect

./tools/shadertoy/convert_shadertoy.py blur.txt Blur --post-process
# Generates compile-ready post-process effect
```

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions