# OpenGLSampler

OpenGL 采样器实现。

## 头文件

```cpp
#include <XCEngine/RHI/OpenGL/OpenGLSampler.h>
```

## 继承关系

```
RHISampler (interface)
└── OpenGLSampler (implementation)
```

## 枚举

### SamplerWrapMode

| 值 | OpenGL 常量 |
|----|-------------|
| `Repeat` | `GL_REPEAT` |
| `MirroredRepeat` | `GL_MIRRORED_REPEAT` |
| `ClampToEdge` | `GL_CLAMP_TO_EDGE` |
| `ClampToBorder` | `GL_CLAMP_TO_BORDER` |

### SamplerFilter

| 值 | OpenGL 常量 |
|----|-------------|
| `Nearest` | `GL_NEAREST` |
| `Linear` | `GL_LINEAR` |
| `NearestMipmapNearest` | `GL_NEAREST_MIPMAP_NEAREST` |
| `LinearMipmapNearest` | `GL_LINEAR_MIPMAP_NEAREST` |
| `NearestMipmapLinear` | `GL_NEAREST_MIPMAP_LINEAR` |
| `LinearMipmapLinear` | `GL_LINEAR_MIPMAP_LINEAR` |

### SamplerCompareMode

| 值 | OpenGL 常量 |
|----|-------------|
| `None` | `GL_NONE` |
| `CompareToRef` | `GL_COMPARE_REF_TO_TEXTURE` |

## OpenGLSamplerDesc

```cpp
struct OpenGLSamplerDesc {
    SamplerFilter minFilter = SamplerFilter::LinearMipmapLinear;
    SamplerFilter magFilter = SamplerFilter::Linear;
    SamplerWrapMode wrapS = SamplerWrapMode::Repeat;
    SamplerWrapMode wrapT = SamplerWrapMode::Repeat;
    SamplerWrapMode wrapR = SamplerWrapMode::Repeat;
    SamplerCompareMode compareMode = SamplerCompareMode::None;
    int compareFunc = 0;
    float maxAnisotropy = 1.0f;
    float minLod = -1000.0f;
    float maxLod = 1000.0f;
};
```

## 公共成员函数

#### `OpenGLSampler()`

#### `~OpenGLSampler() override`

#### `bool Initialize(const OpenGLSamplerDesc& desc)`

#### `void Shutdown() override`

#### `void Bind(unsigned int unit) override`

#### `void Unbind(unsigned int unit) override`

#### `unsigned int GetID() const`

#### `void* GetNativeHandle() override`

## 内部成员

| 成员 | 类型 | 描述 |
|------|------|------|
| `m_sampler` | `unsigned int` | GL sampler ID |
| `m_desc` | `OpenGLSamplerDesc` | 采样器描述 |

## 使用示例

```cpp
OpenGLSampler sampler;
OpenGLSamplerDesc desc;
desc.minFilter = SamplerFilter::LinearMipmapLinear;
desc.magFilter = SamplerFilter::Linear;
desc.wrapS = desc.wrapT = SamplerWrapMode::Repeat;
desc.maxAnisotropy = 16.0f;
sampler.Initialize(desc);

sampler.Bind(0);
glBindTextureUnit(0, texture.GetID());
```