150 lines
3.6 KiB
Markdown
150 lines
3.6 KiB
Markdown
# OpenGLTexture
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OpenGL 纹理的实现，封装 OpenGL texture object。
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## 头文件
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```cpp
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#include <XCEngine/RHI/OpenGL/OpenGLTexture.h>
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```
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## 继承关系
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```
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RHITexture (interface)
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└── OpenGLTexture (implementation)
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```
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## 枚举
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### OpenGLTextureType
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| 值 | 描述 |
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|----|------|
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| `Texture1D` | 1D 纹理 |
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| `Texture2D` | 2D 纹理 |
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| `Texture2DArray` | 2D 纹理数组 |
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| `Texture3D` | 3D 纹理 |
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| `TextureCube` | 立方体贴图 |
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| `TextureCubeArray` | 立方体贴图数组 |
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### OpenGLFormat / OpenGLInternalFormat
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| OpenGLFormat | OpenGLInternalFormat | 描述 |
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|--------------|---------------------|------|
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| `R8` | `1` | 单通道 8-bit |
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| `RG8` | `2` | 双通道 8-bit |
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| `RGBA8` | `4` | 四通道 8-bit |
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| `RGBA16F` | `11` | 四通道 16-bit float |
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| `RGBA32F` | `16` | 四通道 32-bit float |
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| `Depth24Stencil8` | `38` | 24-bit depth + 8-bit stencil |
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| `Depth32F` | `31` | 32-bit float depth |
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| `CompressedDXT1` | `21` | DXT1 压缩 |
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| `CompressedDXT5` | `22` | DXT5 压缩 |
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## 公共成员函数
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### 构造函数与析构函数
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#### `OpenGLTexture()`
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#### `~OpenGLTexture() override`
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### 初始化
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#### `bool Initialize(OpenGLTextureType type, int width, int height, int depth, int mipLevels, OpenGLFormat format, const void* data = nullptr)`
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通用初始化。
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#### `bool Initialize2D(int width, int height, int channels, const void* data, bool generateMipmap = true)`
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便捷的 2D 纹理初始化。
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- `channels`: 通道数 (1-4)
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#### `bool InitializeCubeMap(int size, int mipLevels, OpenGLFormat format, const void* data = nullptr)`
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初始化立方体贴图。
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#### `bool LoadFromFile(const char* path, bool flipVertical = true)`
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从图片文件加载纹理（需要 stb_image）。
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#### `void Shutdown() override`
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### 绑定操作
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#### `void Bind(int slot = 0) const`
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绑定纹理到纹理单元。
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#### `void Unbind() const`
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#### `void BindImage(int slot, bool read, bool write) const`
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绑定为 image texture（用于 compute shader）。
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### 纹理操作
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#### `void GenerateMipmap()`
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生成 Mipmap。
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#### `void SetFiltering(int minFilter, int magFilter)`
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设置过滤模式。
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#### `void SetWrapping(int wrapS, int wrapT, int wrapR = -1)`
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设置纹理环绕模式。
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### 属性
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#### `unsigned int GetID() const`
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获取 OpenGL texture ID。
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#### `OpenGLTextureType GetOpenGLType() const`
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获取纹理类型。
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#### `uint32_t GetWidth() const override`
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#### `uint32_t GetHeight() const override`
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#### `uint32_t GetDepth() const override`
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#### `uint32_t GetMipLevels() const override`
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#### `TextureType GetTextureType() const override`
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转换为 RHI TextureType。
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#### `void* GetNativeHandle() override`
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#### `Format GetFormat() const override / void SetFormat(Format format)`
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#### `const std::string& GetName() const override / void SetName(...)`
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## 内部成员
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| 成员 | 类型 | 描述 |
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|------|------|------|
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| `m_texture` | `unsigned int` | GL texture ID |
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| `m_type` | `OpenGLTextureType` | 纹理类型 |
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| `m_width/height/depth` | `int` | 尺寸 |
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| `m_mipLevels` | `int` | Mipmap 级别 |
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| `m_channels` | `int` | 通道数 |
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| `m_format` | `Format` | RHI 格式 |
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| `m_name` | `std::string` | 名称 |
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## 使用示例
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```cpp
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// Load from file
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OpenGLTexture diffuse;
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diffuse.LoadFromFile("textures/diffuse.png");
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// Create from data
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OpenGLTexture texture;
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unsigned char pixels[] = { ... };
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texture.Initialize2D(512, 512, 4, pixels);
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texture.SetFiltering(GL_LINEAR_MIPMAP_LINEAR, GL_LINEAR);
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texture.SetWrapping(GL_REPEAT, GL_REPEAT);
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texture.GenerateMipmap();
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// Bind
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texture.Bind(0);
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glBindTextureUnit(0, texture.GetID());
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// Compute image binding
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texture.BindImage(0, true, false);
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```
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