feat(3d): Fix ObjectType::PLANE scaling and consolidate ObjectType mapping

- Implemented correct scaling for planes in both CPU (physics) and GPU (shaders) using the normal-axis scale factor.
- Consolidated ObjectType to type_id mapping in Renderer3D to ensure consistency and support for CUBE.
- Fixed overestimation of distance for non-uniformly scaled ground planes, which caused missing shadows.
- Updated documentation and marked Task A.2 as completed.

1 files changed, 11 insertions, 8 deletions

diff --git a/assets/final/shaders/render/scene_query_bvh.wgsl b/assets/final/shaders/render/scene_query_bvh.wgsl
index 61efe49..3e6f895 100644
--- a/assets/final/shaders/render/scene_query_bvh.wgsl
+++ b/assets/final/shaders/render/scene_query_bvh.wgsl
@@ -41,15 +41,18 @@ fn map_scene(p: vec3<f32>, skip_idx: u32) -> f32 {
                 if (obj_idx == skip_idx) { continue; }
                 let obj = object_data.objects[obj_idx];
                 let q = (obj.inv_model * vec4<f32>(p, 1.0)).xyz;
-                let s = min(length(obj.model[0].xyz), min(length(obj.model[1].xyz), length(obj.model[2].xyz)));
-                // IMPORTANT: Plane (type 4.0) and Mesh (type 5.0) should not be scaled by 's'.
-                // The 's' factor is meant for unit primitives (sphere, box, torus) that are
-                // scaled by the model matrix. Meshes already have correct local-space extents.
-                if (obj.params.x != 4.0 && obj.params.x != 5.0) { // Not plane, not mesh
-                    d = min(d, get_dist(q, obj.params) * s);
-                } else {
-                    d = min(d, get_dist(q, obj.params));
+
+                // Extract scale factors from the model matrix
+                let sx = length(obj.model[0].xyz);
+                let sy = length(obj.model[1].xyz);
+                let sz = length(obj.model[2].xyz);
+                
+                var s = min(sx, min(sy, sz));
+                if (obj.params.x == 4.0) {
+                    s = sy; // Plane normal is (0,1,0) in local space
                 }
+                
+                d = min(d, get_dist(q, obj.params) * s);
             } else { // Internal
                 if (stack_ptr < 31) {
                     stack[stack_ptr] = node.left_idx;