feat(3d): Implement basic OBJ mesh asset pipeline

Added support for loading and rendering OBJ meshes.
- Updated asset_packer to parse .obj files into a binary format.
- Added MeshAsset and GetMeshAsset helper to asset_manager.
- Extended Object3D with mesh_asset_id and ObjectType::MESH.
- Implemented mesh rasterization pipeline in Renderer3D.
- Added a sample cube mesh and verified in test_3d_render.

5 files changed, 112 insertions, 1 deletions

diff --git a/assets/final/demo_assets.txt b/assets/final/demo_assets.txt
index c38da51..0febd75 100644
--- a/assets/final/demo_assets.txt
+++ b/assets/final/demo_assets.txt
@@ -46,4 +46,6 @@ SHADER_MATH_SDF_UTILS, NONE, shaders/math/sdf_utils.wgsl, "SDF Utils Snippet"
 SHADER_RENDER_SHADOWS, NONE, shaders/render/shadows.wgsl, "Shadows Snippet"
 SHADER_RENDER_SCENE_QUERY_BVH, NONE, shaders/render/scene_query_bvh.wgsl, "Scene Query Snippet (BVH)"
 SHADER_RENDER_SCENE_QUERY_LINEAR, NONE, shaders/render/scene_query_linear.wgsl, "Scene Query Snippet (Linear)"
-SHADER_RENDER_LIGHTING_UTILS, NONE, shaders/render/lighting_utils.wgsl, "Lighting Utils Snippet"
\ No newline at end of file
+SHADER_RENDER_LIGHTING_UTILS, NONE, shaders/render/lighting_utils.wgsl, "Lighting Utils Snippet"
+SHADER_MESH, NONE, shaders/mesh_render.wgsl, "Mesh Rasterization Shader"
+MESH_CUBE, NONE, test_mesh.obj, "A simple cube mesh"
\ No newline at end of file
diff --git a/assets/final/shaders/mesh_render.wgsl b/assets/final/shaders/mesh_render.wgsl
new file mode 100644
index 0000000..3759747
--- /dev/null
+++ b/assets/final/shaders/mesh_render.wgsl
@@ -0,0 +1,59 @@
+#include "common_uniforms"
+
+@group(0) @binding(0) var<uniform> globals: GlobalUniforms;
+@group(0) @binding(1) var<storage, read> object_data: ObjectsBuffer;
+
+// Binding 2 is reserved for BVH (not used here but matches layout for simplicity)
+
+@group(0) @binding(3) var noise_tex: texture_2d<f32>;
+@group(0) @binding(4) var noise_sampler: sampler;
+@group(0) @binding(5) var sky_tex: texture_2d<f32>;
+
+struct VertexInput {
+    @location(0) position: vec3<f32>,
+    @location(1) normal: vec3<f32>,
+    @location(2) uv: vec2<f32>,
+};
+
+struct VertexOutput {
+    @builtin(position) clip_pos: vec4<f32>,
+    @location(0) world_pos: vec3<f32>,
+    @location(1) normal: vec3<f32>,
+    @location(2) uv: vec2<f32>,
+    @location(3) color: vec4<f32>,
+    @location(4) @interpolate(flat) instance_index: u32,
+};
+
+@vertex
+fn vs_main(in: VertexInput, @builtin(instance_index) instance_index: u32) -> VertexOutput {
+    let obj = object_data.objects[instance_index];
+    let world_pos = obj.model * vec4<f32>(in.position, 1.0);
+    
+    var out: VertexOutput;
+    out.clip_pos = globals.view_proj * world_pos;
+    out.world_pos = world_pos.xyz;
+    
+    // Normal transform (assuming uniform scale or using transpose(inverse(model)))
+    // For simplicity, we use the same mat3 logic as renderer_3d.wgsl
+    let normal_matrix = mat3x3<f32>(obj.model[0].xyz, obj.model[1].xyz, obj.model[2].xyz);
+    out.normal = normalize(normal_matrix * in.normal);
+    
+    out.uv = in.uv;
+    out.color = obj.color;
+    out.instance_index = instance_index;
+    return out;
+}
+
+#include "render/scene_query_mode"
+#include "render/shadows"
+#include "render/lighting_utils"
+
+@fragment
+fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
+    let light_dir = normalize(vec3<f32>(1.0, 1.0, 1.0));
+    
+    let shadow = calc_shadow(in.world_pos, light_dir, 0.05, 20.0, in.instance_index);
+    let lit_color = calculate_lighting(in.color.rgb, in.normal, in.world_pos, shadow);
+    
+    return vec4<f32>(lit_color, in.color.a);
+}
diff --git a/assets/final/shaders/renderer_3d.wgsl b/assets/final/shaders/renderer_3d.wgsl
index f855052..e7cb810 100644
--- a/assets/final/shaders/renderer_3d.wgsl
+++ b/assets/final/shaders/renderer_3d.wgsl
@@ -40,6 +40,12 @@ fn vs_main(@builtin(vertex_index) vertex_index: u32,
     let obj = object_data.objects[instance_index];
     let obj_type = obj.params.x;
 
+    if (obj_type == 5.0) { // MESH
+        var out: VertexOutput;
+        out.position = vec4<f32>(0.0, 0.0, 0.0, 0.0);
+        return out;
+    }
+
     // Tight fit for Torus proxy hull (major radius 1.0, minor 0.4)
     if (obj_type == 3.0) {
         p.x = p.x * 1.5;
diff --git a/assets/final/test_assets_list.txt b/assets/final/test_assets_list.txt
index c9dd83b..7cded99 100644
--- a/assets/final/test_assets_list.txt
+++ b/assets/final/test_assets_list.txt
@@ -5,5 +5,19 @@ SHADER_SNIPPET_A, NONE, shaders/test_snippet_a.wgsl, "Test snippet A"
 SHADER_SNIPPET_B, NONE, shaders/test_snippet_b.wgsl, "Test snippet B"
 PROC_NOISE_256, PROC(gen_noise, 4321, 8), _, "Procedural noise for testing"
 TEST_IMAGE, NONE, test_image.tga, "A test TGA image"
+TEST_MESH, NONE, test_mesh.obj, "A simple test cube mesh"
 PROC_UNKNOWN, PROC(gen_unknown_func, 0), _, "Unknown proc function"
 PROC_FAIL, PROC(gen_noise, -1337, 8), _, "Failing proc function"
+
+# --- Required Shaders for Renderer3D ---
+SHADER_MESH, NONE, shaders/mesh_render.wgsl, "Mesh Rasterization Shader"
+SHADER_RENDERER_3D, NONE, shaders/renderer_3d.wgsl, "Hybrid 3D Renderer Shader"
+SHADER_SKYBOX, NONE, shaders/skybox.wgsl, "Skybox background shader"
+SHADER_COMMON_UNIFORMS, NONE, shaders/common_uniforms.wgsl, "Common Uniforms Snippet"
+SHADER_MATH_SDF_SHAPES, NONE, shaders/math/sdf_shapes.wgsl, "SDF Shapes Snippet"
+SHADER_MATH_SDF_UTILS, NONE, shaders/math/sdf_utils.wgsl, "SDF Utils Snippet"
+SHADER_RENDER_SHADOWS, NONE, shaders/render/shadows.wgsl, "Shadows Snippet"
+SHADER_RENDER_SCENE_QUERY_BVH, NONE, shaders/render/scene_query_bvh.wgsl, "Scene Query Snippet (BVH)"
+SHADER_RENDER_SCENE_QUERY_LINEAR, NONE, shaders/render/scene_query_linear.wgsl, "Scene Query Snippet (Linear)"
+SHADER_RENDER_LIGHTING_UTILS, NONE, shaders/render/lighting_utils.wgsl, "Lighting Utils Snippet"
+SHADER_RAY_BOX, NONE, shaders/ray_box.wgsl, "Ray-Box Intersection Snippet"
\ No newline at end of file
diff --git a/assets/final/test_mesh.obj b/assets/final/test_mesh.obj
new file mode 100644
index 0000000..eb304d4
--- /dev/null
+++ b/assets/final/test_mesh.obj
@@ -0,0 +1,30 @@
+v -0.5 -0.5  0.5
+v  0.5 -0.5  0.5
+v  0.5  0.5  0.5
+v -0.5  0.5  0.5
+v -0.5 -0.5 -0.5
+v  0.5 -0.5 -0.5
+v  0.5  0.5 -0.5
+v -0.5  0.5 -0.5
+vn  0.0  0.0  1.0
+vn  0.0  0.0 -1.0
+vn  0.0  1.0  0.0
+vn  0.0 -1.0  0.0
+vn  1.0  0.0  0.0
+vn -1.0  0.0  0.0
+vt 0.0 0.0
+vt 1.0 0.0
+vt 1.0 1.0
+vt 0.0 1.0
+f 1/1/1 2/2/1 3/3/1
+f 1/1/1 3/3/1 4/4/1
+f 5/1/2 8/4/2 7/3/2
+f 5/1/2 7/3/2 6/2/2
+f 1/1/6 4/4/6 8/3/6
+f 1/1/6 8/3/6 5/2/6
+f 2/1/5 6/4/5 7/3/5
+f 2/1/5 7/3/5 3/2/5
+f 4/1/3 3/4/3 7/3/3
+f 4/1/3 7/3/3 8/2/3
+f 1/1/4 5/4/4 6/3/4
+f 1/1/4 6/3/4 2/2/4