# Visual Debugging System

The `VisualDebug` class provides immediate-mode style 3D wireframe rendering for debugging purposes. It is stripped from the final binary when `STRIP_ALL` is defined.

## Features

- **Wireframe Primitives**: Boxes, AABBs, Spheres, Cones, Crosses, Lines.
- **Trajectories**: Visualize paths with `add_trajectory`.
- **Mesh Normals**: Visualize vertex normals.
- **Zero Overhead**: Code is compiled out in release builds.

## Usage

Access the instance via `Renderer3D::GetVisualDebug()` (only available if `!STRIP_ALL`).

```cpp
#if !defined(STRIP_ALL)
  VisualDebug& dbg = renderer.GetVisualDebug();
  
  // Draw a red box at origin
  dbg.add_box(mat4::identity(), vec3(1,1,1), vec3(1,0,0));
  
  // Draw a trajectory
  std::vector<vec3> path = { ... };
  dbg.add_trajectory(path, vec3(0,1,0));
  
  // Draw a light cone
  dbg.add_cone(light_pos, light_dir, range, radius, vec3(1,1,0));
#endif
```

## Primitives

- `add_line(start, end, color)`: Basic line segment.
- `add_cross(center, size, color)`: 3D cross (useful for points).
- `add_sphere(center, radius, color)`: Wireframe sphere (3 axis circles).
- `add_cone(apex, dir, height, radius, color)`: Wireframe cone (useful for spotlights).
- `add_box(transform, half_extent, color)`: OBB.
- `add_aabb(min, max, color)`: Axis-aligned box.
- `add_trajectory(points, color)`: Polyline.

## Integration

The `VisualDebug::render` method is called automatically by `Renderer3D::draw` if `s_debug_enabled_` is true.
To enable globally:
```cpp
Renderer3D::SetDebugEnabled(true);
```