jpmschweitzerandClaude Opus 4.6
f204bf3372
Proves the full asset pipeline: concept image → Trellis 3D → Blender post-process → Godot render with toon shader and recolor masks. Key findings: - gltf/embedded_image_handling=3 required (extract mode silently fails) - Luminance-preserving recolor shader keeps texture detail - Trellis output quality is sufficient for isometric game assets - Camera uses pivot-based system with screen-aligned WASD pan Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
115 lines
4.3 KiB
Markdown
115 lines
4.3 KiB
Markdown
# 3D Pipeline Spike
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Proof of concept for the Trellis image-to-3D asset pipeline with runtime
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recoloring in Godot 4.6.
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## What This Proves
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1. **Trellis generates usable 3D assets** from 2D concept art (via /image-gen)
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2. **Blender post-processing** normalizes scale, centers models, generates
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recolor masks, and adjusts materials for toon rendering
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3. **Godot renders textured GLBs** with embedded textures when
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`gltf/embedded_image_handling=3` (embed uncompressed) is set
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4. **Luminance-preserving recoloring** via shader + mask sidecar: tint the
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dominant color region while keeping texture detail (shadows, highlights,
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edges)
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## Pipeline
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```
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concept.png ──→ Trellis ──→ raw.glb ──→ Blender postprocess ──→ model.glb + mask.png
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│
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Godot import
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(embedded textures)
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│
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toon_masked.gdshader
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(texture + mask + tint)
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```
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## Key Findings
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### GLB Import Settings (Critical)
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Godot's GLTF importer `gltf/embedded_image_handling` values:
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| Value | Mode | Result |
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|-------|------|--------|
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| 0 | Discard textures | Models render without any texture |
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| 1 | Extract textures | **Silently fails** — materials get null texture refs |
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| 2 | Embed as Basis Universal | Compressed, may lose quality |
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| 3 | Embed uncompressed | **Works correctly** — textures preserved in .scn |
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**Always use value 3** for Trellis-generated GLBs. Set in project.godot under
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`[gltf]` so new imports pick it up automatically.
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### Recolor Shader
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The `toon_masked.gdshader` uses luminance-preserving blending:
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```glsl
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float luma = dot(original.rgb, vec3(0.299, 0.587, 0.114));
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vec3 tinted = tint_color.rgb * (luma * 1.5 + 0.2);
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vec3 base = mix(original.rgb, tinted, mask);
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```
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- Where `mask = 0` (black): original Trellis texture preserved
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- Where `mask = 1` (white): tint color applied, scaled by original luminance
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- This keeps shadows, highlights, and detail lines even in recolored regions
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The mask default is `hint_default_black` (replace nothing when no mask loaded).
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### Toon Shadow
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Gentle 15% darkening with `smoothstep` transition — not the harsh binary
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shadow/lit split. This preserves texture readability at isometric camera angles
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where many faces would otherwise be fully in shadow.
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### Alpha / See-Through Fix
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Trellis texture atlases sometimes have alpha artifacts at UV seams. The shader
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does NOT output ALPHA — all models render fully opaque. If transparency is
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needed for specific assets (glass, holograms), use a separate shader variant.
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## Running
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```bash
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cd spikes/3dpipeline
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godot --headless --import # first time only — generates .godot/imported/
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godot --path . # run the spike
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```
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### Controls
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| Key | Action |
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|-----|--------|
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| WASD | Pan camera (screen-aligned) |
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| Mouse wheel | Zoom in/out |
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| T | Cycle camera angle (top-down / 45 iso / 30 dramatic) |
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| R | Randomize character colors |
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## Files
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```
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project.godot # Minimal Godot project config
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scenes/spike_3d.tscn # Main scene (Camera3D + script)
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scripts/spike/spike_main.gd # Camera, model loading, shader application
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shaders/spike/toon_masked.gdshader # Texture + recolor mask + toon shadow
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shaders/spike/toon.gdshader # Flat color toon (characters)
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shaders/spike/outline.gdshader # Inverted hull outline (not used yet)
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models/furniture/*.glb + *_mask.png # Post-processed Trellis models + masks
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models/props/*.glb + *_mask.png # Post-processed Trellis props + masks
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```
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## Known Issues
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- Baroque table mask is too aggressive — tints the whole model bright white
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- Character scale needs tuning relative to furniture
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- Trellis mesh quality varies — some models have holes visible at close zoom
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- No outline shader applied yet (inverted hull ready but not wired up)
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## Dependencies
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- Godot 4.6+ (gl_compatibility renderer)
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- Models generated by: `tooling/db/trellis_connector.py` + `.claude/skills/glb-gen/`
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- Concept images generated by: `.claude/skills/image-gen/`
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