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.

2 files changed, 83 insertions, 0 deletions

diff --git a/src/procedural/generator.cc b/src/procedural/generator.cc
new file mode 100644
index 0000000..3d969ba
--- /dev/null
+++ b/src/procedural/generator.cc
@@ -0,0 +1,56 @@
+// This file is part of the 64k demo project.
+// It implements basic procedural texture generators.
+
+#include "procedural/generator.h"
+#include <cmath>
+#include <cstdlib>
+
+namespace procedural {
+
+// Simple noise generator
+// Params[0]: Seed (optional, if 0 uses rand())
+// Params[1]: Intensity (0.0 - 1.0)
+void gen_noise(uint8_t* buffer, int w, int h, const float* params,
+               int num_params) {
+  float intensity = (num_params > 1) ? params[1] : 1.0f;
+  if (num_params > 0 && params[0] != 0) {
+    srand((unsigned int)params[0]);
+  }
+
+  for (int i = 0; i < w * h; ++i) {
+    uint8_t val = (uint8_t)((rand() % 255) * intensity);
+    buffer[i * 4 + 0] = val; // R
+    buffer[i * 4 + 1] = val; // G
+    buffer[i * 4 + 2] = val; // B
+    buffer[i * 4 + 3] = 255; // A
+  }
+}
+
+// Simple grid generator
+// Params[0]: Grid Size (pixels)
+// Params[1]: Line Thickness (pixels)
+void gen_grid(uint8_t* buffer, int w, int h, const float* params,
+              int num_params) {
+  int grid_size = (num_params > 0) ? (int)params[0] : 32;
+  int thickness = (num_params > 1) ? (int)params[1] : 2;
+
+  if (grid_size < 1)
+    grid_size = 32;
+
+  for (int y = 0; y < h; ++y) {
+    for (int x = 0; x < w; ++x) {
+      bool on_line = ((x % grid_size) < thickness) ||
+                     ((y % grid_size) < thickness);
+
+      int idx = (y * w + x) * 4;
+      uint8_t val = on_line ? 255 : 0;
+
+      buffer[idx + 0] = val;
+      buffer[idx + 1] = val;
+      buffer[idx + 2] = val;
+      buffer[idx + 3] = 255;
+    }
+  }
+}
+
+} // namespace procedural
diff --git a/src/procedural/generator.h b/src/procedural/generator.h
new file mode 100644
index 0000000..a5ced68
--- /dev/null
+++ b/src/procedural/generator.h
@@ -0,0 +1,27 @@
+// This file is part of the 64k demo project.
+// It defines the interface for procedural texture generation.
+// Used to generate texture data at runtime.
+
+#pragma once
+
+#include <cstdint>
+#include <vector>
+
+// Procedural generation function signature
+// buffer: Pointer to RGBA8 buffer (size w * h * 4)
+// w, h: Dimensions
+// params: Arbitrary float parameters for the generator
+typedef void (*ProcGenFunc)(uint8_t* buffer, int w, int h, const float* params,
+                            int num_params);
+
+namespace procedural {
+
+// Example: Simple noise generator
+void gen_noise(uint8_t* buffer, int w, int h, const float* params,
+               int num_params);
+
+// Example: Grid pattern
+void gen_grid(uint8_t* buffer, int w, int h, const float* params,
+              int num_params);
+
+} // namespace procedural