fix(3d): Unify all objects to SDF path for consistent shadows

- Updated ObjectData to include inv_model for reliable world-to-local mapping.
- Enabled SDF raymarching path for all objects in test_3d_render (floor is now a large SDF BOX).
- Implemented robust normal calculation using SDF gradient for all objects.
- Standardized lighting (light_dir = 1,1,1) and diffuse+ambient model.
- Refined calc_shadow with instance-based skip_idx and robust bias.
- Fixed non-uniform scale handling in shader by extracting min scale from model matrix.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/3d/renderer.h b/src/3d/renderer.h
index a7f29da..c6ca2a3 100644
--- a/src/3d/renderer.h
+++ b/src/3d/renderer.h
@@ -23,7 +23,7 @@ struct GlobalUniforms {
 // Matches the GPU struct layout
 struct ObjectData {
   mat4 model;
-  mat4 model_inverse_transpose;
+  mat4 inv_model;
   vec4 color;
   vec4 params; // Type, etc.
 };