68 lines
1.4 KiB
Markdown
68 lines
1.4 KiB
Markdown
|
# AABB / OBB
|
||
|
|
|
||
|
|
轴对齐包围盒 (AABB) 和有向包围盒 (OBB)。
|
||
|
|
|
||
|
|
## 头文件
|
||
|
|
|
||
|
|
```cpp
|
||
|
|
#include <XCEngine/Math/AABB.h>
|
||
|
|
```
|
||
|
|
|
||
|
|
## 命名空间
|
||
|
|
|
||
|
|
`XCEngine::Math`
|
||
|
|
|
||
|
|
## AABB - 轴对齐包围盒
|
||
|
|
|
||
|
|
`AABB` 在 Math 库中通过 `Bounds` 类型实现，参见 [math-bounds.md](math-bounds.md)。
|
||
|
|
|
||
|
|
## OBB - 有向包围盒
|
||
|
|
|
||
|
|
OBB 是可以任意方向旋转的包围盒。
|
||
|
|
|
||
|
|
```cpp
|
||
|
|
struct OBB {
|
||
|
|
Vector3 center;
|
||
|
|
Vector3 extents; // 半长
|
||
|
|
Matrix4 transform; // 变换矩阵
|
||
|
|
};
|
||
|
|
```
|
||
|
|
|
||
|
|
### 构造函数
|
||
|
|
|
||
|
|
- `OBB()` - 默认构造
|
||
|
|
- `OBB(const Vector3& center, const Vector3& extents)` - 从中心和半长构造
|
||
|
|
|
||
|
|
### 实例方法
|
||
|
|
|
||
|
|
| 方法 | 返回值 | 描述 |
|
||
|
|
|------|--------|------|
|
||
|
|
| `GetAxis(index)` | `Vector3` | 获取局部轴 (0=X, 1=Y, 2=Z) |
|
||
|
|
| `GetMin()` | `Vector3` | 局部空间最小点 |
|
||
|
|
| `GetMax()` | `Vector3` | 局部空间最大点 |
|
||
|
|
| `Contains(point)` | `bool` | 点是否在 OBB 内 |
|
||
|
|
| `Intersects(OBB)` | `bool` | 与另一个 OBB 相交 (SAT) |
|
||
|
|
| `Intersects(Sphere)` | `bool` | 与球体相交 |
|
||
|
|
|
||
|
|
## 备注
|
||
|
|
|
||
|
|
- AABB 与轴对齐，检测简单但可能不够紧凑
|
||
|
|
- OBB 可旋转，检测使用分离轴定理 (SAT)
|
||
|
|
- OBB 适合动态旋转的物体
|
||
|
|
|
||
|
|
## 使用示例
|
||
|
|
|
||
|
|
```cpp
|
||
|
|
// OBB
|
||
|
|
OBB obb;
|
||
|
|
obb.center = Vector3(0.0f);
|
||
|
|
obb.extents = Vector3(1.0f);
|
||
|
|
obb.transform = Matrix4::TRS(pos, rot, scale);
|
||
|
|
|
||
|
|
Vector3 localAxis = obb.GetAxis(0);
|
||
|
|
|
||
|
|
if (obb.Contains(point)) { ... }
|
||
|
|
if (obb.Intersects(otherOBB)) { ... }
|
||
|
|
if (obb.Intersects(sphere)) { ... }
|
||
|
|
```
|