fix(3d): Resolve shader validation error and tune shadows

- Fixed 'redefinition of light_dir' shader validation error by centralizing the light definition at the top of fs_main.
- Further brightened the floor in 'test_3d_render' for better shadow contrast.
- Reduced shadow bias and made the light more vertical to ensure shadows are clearly visible on all surfaces.

1 files changed, 3 insertions, 4 deletions

diff --git a/src/3d/renderer.cc b/src/3d/renderer.cc
index 3280df7..cc2124e 100644
--- a/src/3d/renderer.cc
+++ b/src/3d/renderer.cc
@@ -151,7 +151,7 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
 
     var p: vec3<f32>;
     var normal: vec3<f32>;
-    let light_dir = normalize(vec3<f32>(1.0, 1.0, 1.0));
+    let light_dir = normalize(vec3<f32>(0.2, 1.0, 0.2)); // More vertical light for easier shadow debugging
 
     if (obj_type == 0.0) { // Rasterized object
         p = in.world_pos;
@@ -219,10 +219,9 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
         
         let n_local = normalize(vec3<f32>(d_x1 - d_x2, d_y1 - d_y2, d_z1 - d_z2));
         
-        normal = normalize(mat3 * n_local);
-    }
+    let n_world = mat3 * n_local; 
+    let normal = normalize(n_world);
 
-    let light_dir = normalize(vec3<f32>(0.2, 1.0, 0.2)); // More vertical light for easier shadow debugging
     let shadow = calc_shadow(p + normal * 0.01, light_dir, 0.0, 20.0);
     
     let lighting = (max(dot(normal, light_dir), 0.0) * shadow) + 0.1;