feat(gpu): Implement recursive WGSL composition and modularize shaders (Task #50)

- Updated ShaderComposer to support recursive #include "snippet_name" with cycle detection.
- Extracted granular WGSL snippets: math/sdf_shapes, math/sdf_utils, render/shadows, render/scene_query, render/lighting_utils.
- Refactored Renderer3D to use #include in shaders, simplifying C++ dependency lists.
- Fixed WGPUShaderSourceWGSL usage on macOS to correctly handle composed shader strings.
- Added comprehensive unit tests for recursive composition in test_shader_composer.
- Verified system stability with test_3d_render and full test suite.
- Marked Task #50 as recurrent for future code hygiene.

1 files changed, 9 insertions, 35 deletions

diff --git a/assets/final/shaders/renderer_3d.wgsl b/assets/final/shaders/renderer_3d.wgsl
index 7be8d4e..b39525d 100644
--- a/assets/final/shaders/renderer_3d.wgsl
+++ b/assets/final/shaders/renderer_3d.wgsl
@@ -1,3 +1,5 @@
+#include "common_uniforms"
+
 @group(0) @binding(0) var<uniform> globals: GlobalUniforms;
 @group(0) @binding(1) var<storage, read> object_data: ObjectsBuffer;
 @group(0) @binding(2) var noise_tex: texture_2d<f32>;
@@ -54,37 +56,10 @@ fn vs_main(@builtin(vertex_index) vertex_index: u32,
     return out;
 }
 
-fn get_dist(p: vec3<f32>, obj_type: f32) -> f32 {
-    if (obj_type == 1.0) { return length(p) - 1.0; } // Unit Sphere
-    if (obj_type == 2.0) { return sdBox(p, vec3<f32>(1.0)); } // Unit Box
-    if (obj_type == 3.0) { return sdTorus(p, vec2<f32>(1.0, 0.4)); } // Unit Torus
-    if (obj_type == 4.0) { return sdPlane(p, vec3<f32>(0.0, 1.0, 0.0), 0.0); }
-    return 100.0;
-}
-
-fn map_scene(p: vec3<f32>, skip_idx: u32) -> f32 {
-    var d = 1000.0;
-    let count = u32(globals.params.x);
-    
-    for (var i = 0u; i < count; i = i + 1u) {
-        if (i == skip_idx) { continue; }
-        let obj = object_data.objects[i];
-        let obj_type = obj.params.x;
-        // Skip rasterized objects (like the floor) in the SDF map
-        if (obj_type <= 0.0) { continue; } 
-
-        let q = (obj.inv_model * vec4<f32>(p, 1.0)).xyz;
-        
-        let scale_x = length(obj.model[0].xyz);
-        let scale_y = length(obj.model[1].xyz);
-        let scale_z = length(obj.model[2].xyz);
-        // Use conservative minimum scale to avoid overstepping the distance field
-        let s = min(scale_x, min(scale_y, scale_z));
-        
-        d = min(d, get_dist(q, obj_type) * s);
-    }
-    return d;
-}
+#include "render/scene_query"
+#include "render/shadows"
+#include "render/lighting_utils"
+#include "ray_box"
 
 @fragment
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
@@ -189,7 +164,6 @@ fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     }
 
     let shadow = calc_shadow(p, light_dir, 0.05, 20.0, in.instance_index);
-    let diffuse = max(dot(normal, light_dir), 0.0);
-    let lighting = diffuse * (0.1 + 0.9 * shadow) + 0.1; // Ambient + Shadowed Diffuse
-    return vec4<f32>(base_color * lighting, 1.0);
-}
\ No newline at end of file
+    let lit_color = calculate_lighting(base_color, normal, p, shadow);
+    return vec4<f32>(lit_color, 1.0);
+}