feat: Implement 3D system and procedural texture manager

- Extended mini_math.h with mat4 multiplication and affine transforms.
- Implemented TextureManager for runtime procedural texture generation and GPU upload.
- Added 3D system components: Camera, Object, Scene, and Renderer3D.
- Created test_3d_render mini-demo for interactive 3D verification.
- Fixed WebGPU validation errors regarding depthSlice and unimplemented WaitAny.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/tests/test_maths.cc b/src/tests/test_maths.cc
index d9bc4d1..64bbb45 100644
--- a/src/tests/test_maths.cc
+++ b/src/tests/test_maths.cc
@@ -110,6 +110,25 @@ void test_matrices() {
   mat4 view = mat4::look_at(eye, target, up);
   // Point (0,0,0) in world should be at (0,0,-5) in view space
   assert(near(view.m[14], -5.0f));
+
+  // Test matrix multiplication
+  mat4 t = mat4::translate({1, 2, 3});
+  mat4 s = mat4::scale({2, 2, 2});
+  mat4 ts = t * s; // Scale then Translate (if applied to vector on right: M*v)
+
+  // v = (1,1,1,1) -> scale(2,2,2) -> (2,2,2,1) -> translate(1,2,3) -> (3,4,5,1)
+  vec4 v(1, 1, 1, 1);
+  vec4 res = ts * v;
+  assert(near(res.x, 3.0f));
+  assert(near(res.y, 4.0f));
+  assert(near(res.z, 5.0f));
+
+  // Test Rotation
+  // Rotate 90 deg around Z. (1,0,0) -> (0,1,0)
+  mat4 r = mat4::rotate({0, 0, 1}, 1.570796f);
+  vec4 v_rot = r * vec4(1, 0, 0, 1);
+  assert(near(v_rot.x, 0.0f));
+  assert(near(v_rot.y, 1.0f));
 }
 
 // Tests easing curves