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.

1 files changed, 59 insertions, 0 deletions

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);
+}