Combined image sampler (texture/combined_image_sampler.md) (#77)

Co-authored-by: Cousin Ze <2571851049@qq.com>

TERMINOLOGY.csv

@@ -142,6 +142,7 @@ command,名词,Vulkan概念,函数,"Vulkan API 中的函数，例如 vkCreateGra
 uniform buffer object,名词,Vulkan概念,uniform 缓冲对象,注意我们不翻译 uniform 这个词,,
 descriptor set,名词,Vulkan概念,描述符集合,,,
 descriptor set layout,名词,Vulkan概念,描述符集合布局,,,
+combined image sampler,名词,Vulkan概念,组合图像采样器,,,
 addressing mode,名词,Vulkan概念,寻址模式,,,
 ,,,,,,
 C style,形容词,C语言概念,类 C,,GLSL is a shading language with a C-style syntax,

book/src/SUMMARY.md

@@ -53,7 +53,7 @@
 
 - [图像](./texture/images.md)
 - [图像视图与采样器](./texture/image_view_and_sampler.md)
-- [Combined image sampler](./texture/combined_image_sampler.md)
+- [组合图像采样器](./texture/combined_image_sampler.md)
 
 # 模型
 

book/src/texture/combined_image_sampler.md

@@ -1,14 +1,18 @@
-# Combined image sampler
+# 组合图像采样器
 
-**Code:** [main.rs](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/src/25_texture_mapping.rs) | [shader.vert](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/shaders/25/shader.vert) | [shader.frag](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/shaders/25/shader.frag)
+> 原文链接：<https://kylemayes.github.io/vulkanalia/texture/combined_immage_sampler.html>
+>
+> Commit Hash: 72b9244ea1d53fa0cf40ce9dbf854c43286bf745
 
-We looked at descriptors for the first time in the uniform buffers part of the tutorial. In this chapter we will look at a new type of descriptor: *combined image sampler*. This descriptor makes it possible for shaders to access an image resource through a sampler object like the one we created in the previous chapter.
+**本章代码:** [main.rs](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/src/25_texture_mapping.rs) | [shader.vert](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/shaders/25/shader.vert) | [shader.frag](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/shaders/25/shader.frag)
 
-We'll start by modifying the descriptor set layout, descriptor pool and descriptor set to include such a combined image sampler descriptor. After that, we're going to add texture coordinates to `Vertex` and modify the fragment shader to read colors from the texture instead of just interpolating the vertex colors.
+我们在 uniform 缓冲部分第一次认识了描述符。在本章中我们将看到一种新的描述符：*组合图像采样器*。这种描述符使得着色器可以通过像我们在上一章中创建的采样器对象来访问图像资源。
 
-## Updating the descriptors
+首先我们修改描述符集合布局、描述符池以及描述符集合，使其包含一个组合图像采样器描述符。然后我们将在 `Vertex` 中添加纹理坐标，并修改片元着色器，使其从纹理中读取颜色而不是仅仅插值顶点颜色。
 
-Browse to the `^create_descriptor_set_layout` function and add a `vk::DescriptorSetLayoutBinding` for a combined image sampler descriptor. We'll simply put it in the binding after the uniform buffer:
+## 更新描述符
+
+在 `create_descriptor_set_layout` 函数中为组合图像采样器描述符添加一个 `vk::DescriptorSetLayoutBinding`。我们将其放在 uniform 缓冲之后的绑定中：
 
 ```rust,noplaypen
 let sampler_binding = vk::DescriptorSetLayoutBinding::builder()
@@ -22,9 +26,9 @@ let info = vk::DescriptorSetLayoutCreateInfo::builder()
     .bindings(bindings);
 ```
 
-Make sure to set the `stage_flags` to indicate that we intend to use the combined image sampler descriptor in the fragment shader. That's where the color of the fragment is going to be determined. It is possible to use texture sampling in the vertex shader, for example to dynamically deform a grid of vertices by a [heightmap](https://en.wikipedia.org/wiki/Heightmap).
+记得将 `stage_flags` 设为 `vk::ShaderStageFlags::FRAGMENT`，以指示我们将会在片元着色器中使用组合图像采样器描述符 —— 这是片元的颜色将会被确定的地方。在顶点着色器中使用纹理采样是可能的，例如通过[高度图](https://en.wikipedia.org/wiki/Heightmap)动态地改变顶点网格的形状。
 
-We must also create a larger descriptor pool to make room for the allocation of the combined image sampler by adding another `vk::DescriptorPoolSize` of type `vk::DescriptorType::COMBINED_IMAGE_SAMPLER` to the `vk::DescriptorPoolCreateInfo`. Go to the `^create_descriptor_pool` function and modify it to include a `vk::DescriptorPoolSize` for this descriptor:
+我们必须创建一个更大的描述符池，在 `vk::DescriptorPoolCreateInfo` 中添加另一个 `vk::DescriptorType::COMBINED_IMAGE_SAMPLER` 类型的 `vk::DescriptorPoolSize`，从而为组合图像采样器的分配腾出空间。转到 `create_descriptor_pool` 函数，为组合图像采样器描述符添加一个 `vk::DescriptorPoolSize`：
 
 ```rust,noplaypen
 let sampler_size = vk::DescriptorPoolSize::builder()
@@ -37,11 +41,11 @@ let info = vk::DescriptorPoolCreateInfo::builder()
     .max_sets(data.swapchain_images.len() as u32);
 ```
 
-Inadequate descriptor pools are a good example of a problem that the validation layers will not catch: As of Vulkan 1.1, `allocate_descriptor_sets` may fail with the error code `vk::ErrorCode::OUT_OF_POOL_MEMORY` if the pool is not sufficiently large, but the driver may also try to solve the problem internally. This means that sometimes (depending on hardware, pool size and allocation size) the driver will let us get away with an allocation that exceeds the limits of our descriptor pool. Other times, `allocate_descriptor_sets` will fail and return `vk::ErrorCode::OUT_OF_POOL_MEMORY`. This can be particularly frustrating if the allocation succeeds on some machines, but fails on others.
+有一些问题是校验层无法捕获的，描述符池不够大就是一个很好的例子：从 Vulkan 1.1 开始，如果描述符池不够大，`allocate_descriptor_sets` 可能会失败并返回错误码 `vk::ErrorCode::OUT_OF_POOL_MEMORY`，但驱动程序也可能会尝试在内部解决这个问题。这意味着有时（取决于硬件、池大小和分配大小）驱动程序会允许我们超出描述符池的限制。其他时候，`allocate_descriptor_sets` 将会失败并返回 `vk::ErrorCode::OUT_OF_POOL_MEMORY`。如果分配在某些机器上成功，但在其他机器上失败，这可能会让人特别沮丧。
 
-Since Vulkan shifts the responsiblity for the allocation to the driver, it is no longer a strict requirement to only allocate as many descriptors of a certain type (`vk::DescriptorType::COMBINED_IMAGE_SAMPLER`, etc.) as specified by the corresponding `descriptor_count` members for the creation of the descriptor pool. However, it remains best practise to do so, and in the future, `VK_LAYER_KHRONOS_validation` will warn about this type of problem if you enable [Best Practice Validation](https://vulkan.lunarg.com/doc/view/1.1.126.0/windows/best_practices.html).
+因为 Vulkan 把分配的责任转移给了驱动程序，所以只分配与描述符池创建时相应的 `descriptor_count` 成员指定的某种类型的描述符（`vk::DescriptorType::COMBINED_IMAGE_SAMPLER` 等）不再是一个严格的要求。然而，最好还是这样做。并且在将来，如果你启用了[最佳实践校验](https://vulkan.lunarg.com/doc/view/1.1.126.0/windows/best_practices.html)，`VK_LAYER_KHRONOS_validation` 将会对这种类型的问题发出警告。
 
-The final step is to bind the actual image and sampler resources to the descriptors in the descriptor set. Go to the `create_descriptor_sets` function. The resources for a combined image sampler structure must be specified in a `vk::DescriptorImageInfo` struct, just like the buffer resource for a uniform buffer descriptor is specified in a `vk::DescriptorBufferInfo` struct. This is where the objects from the previous chapter come together.
+最后一步就是将实际的图像和采样器绑定到描述符集合中的描述符上了。转到 `create_descriptor_sets` 函数。组合图像采样器结构的资源必须在 `vk::DescriptorImageInfo` 结构中指定，就像 uniform 缓冲描述符的缓冲资源在 `vk::DescriptorBufferInfo` 结构中指定一样。这就是前一章中的对象结合在一起的地方。
 
 ```rust,noplaypen
 let info = vk::DescriptorImageInfo::builder()
@@ -63,11 +67,11 @@ device.update_descriptor_sets(
 );
 ```
 
-The descriptors must be updated with this image info, just like the buffer. This time we're using the `image_info` array instead of `buffer_info`. The descriptors are now ready to be used by the shaders!
+描述符需要使用图像信息更新。这一次我们使用 `image_info` 数组，而不是 `buffer_info`。描述符现在已经可以被着色器使用了！
 
-## Texture coordinates
+## 纹理坐标
 
-There is one important ingredient for texture mapping that is still missing, and that's the actual coordinates for each vertex. The coordinates determine how the image is actually mapped to the geometry.
+纹理映射还缺少一个重要的组成部分，那就是每个顶点的实际坐标。这些坐标决定了图像如何映射到几何体上。
 
 ```rust,noplaypen
 #[repr(C)]
@@ -115,7 +119,7 @@ impl Vertex {
 }
 ```
 
-Modify the `Vertex` struct to include a `Vec2` for texture coordinates. Make sure to also add a `vk::VertexInputAttributeDescription` so that we can use access texture coordinates as input in the vertex shader. That is necessary to be able to pass them to the fragment shader for interpolation across the surface of the square.
+修改 `Vertex` 结构体并为纹理坐标添加一个 `Vec2` 类型的字段。记得也添加一条 `vk::VertexInputAttributeDescription`，这样我们就能在顶点着色器中访问纹理坐标了。这样我们才能将它们从顶点着色器传递给片元着色器，以便在正方形表面上进行插值。
 
 ```rust,noplaypen
 static VERTICES: [Vertex; 4] = [
@@ -126,11 +130,11 @@ static VERTICES: [Vertex; 4] = [
 ];
 ```
 
-In this tutorial, I will simply fill the square with the texture by using coordinates from `0, 0` in the top-left corner to `1, 1` in the bottom-right corner. Feel free to experiment with different coordinates. Try using coordinates below `0` or above `1` to see the addressing modes in action!
+在本教程中，我会简单地使用左上角为 `0, 0`，右下角为 `1, 1` 的坐标填充正方形。你可以随意尝试不同的坐标，并试着使用小于 `0` 或大于 `1` 的坐标来看看寻址模式的效果！
 
-## Shaders
+## 着色器
 
-The final step is modifying the shaders to sample colors from the texture. We first need to modify the vertex shader to pass through the texture coordinates to the fragment shader:
+最后一步就是修改着色器，使其从纹理中采样出颜色。 我们首先需要修改顶点着色器，将纹理坐标传递给片元着色器：
 
 ```glsl
 layout(location = 0) in vec2 inPosition;
@@ -147,7 +151,7 @@ void main() {
 }
 ```
 
-Just like the per vertex colors, the `fragTexCoord` values will be smoothly interpolated across the area of the square by the rasterizer. We can visualize this by having the fragment shader output the texture coordinates as colors:
+和逐顶点颜色一样，`fragTexCoord` 值也会被光栅化器在正方形区域内平滑插值。我们可以通过让片元着色器将纹理坐标作为颜色输出来可视化这一点：
 
 ```glsl
 #version 450
@@ -162,31 +166,31 @@ void main() {
 }
 ```
 
-You should see something like the image below. Don't forget to recompile the shaders!
+别忘记重新编译着色器！之后，你应该会看到下面的图像。
 
 ![](../images/texcoord_visualization.png)
 
-The green channel represents the horizontal coordinates and the red channel the vertical coordinates. The black and yellow corners confirm that the texture coordinates are correctly interpolated from `0, 0` to `1, 1` across the square. Visualizing data using colors is the shader programming equivalent of `printf` debugging, for lack of a better option!
+绿色通道代表了水平坐标，红色通道代表了垂直坐标。黑色和黄色的角落证实了纹理坐标在正方形上从 `0, 0` 插值到 `1, 1` 的正确性。使用颜色可视化数据是着色器编程中的 `printf` 调试等效方法，因为没有更好的选择！
 
-A combined image sampler descriptor is represented in GLSL by a sampler uniform. Add a reference to it in the fragment shader:
+组合图像采样器描述符在 GLSL 中是使用采样器 uniform 表示的。在片元着色器中添加一个引用：
 
 ```glsl
 layout(binding = 1) uniform sampler2D texSampler;
 ```
 
-There are equivalent `sampler1D` and `sampler3D` types for other types of images. Make sure to use the correct binding here.
+对于其他类型的图像，有等效的 `sampler1D` 和 `sampler3D` 类型。记得在这里使用正确的绑定。
 
 ```glsl
 void main() {
     outColor = texture(texSampler, fragTexCoord);
 }
 ```
 
-Textures are sampled using the built-in `texture` function. It takes a `sampler` and coordinate as arguments. The sampler automatically takes care of the filtering and transformations in the background. You should now see the texture on the square when you run the application:
+使用内建的 `texture` 函数采样纹理。`texture` 函数接受一个 `sampler` 和一个坐标作为参数。采样器会自动处理过滤和变换。当你运行应用程序时，你应该会在正方形上看到纹理：
 
 ![](../images/texture_on_square.png)
 
-Try experimenting with the addressing modes by scaling the texture coordinates to values higher than `1`. For example, the following fragment shader produces the result in the image below when using `vk::SamplerAddressMode::REPEAT`:
+试着缩放纹理坐标，得到大于 `1` 的值，来试验寻址模式的功能。例如，当使用 `vk::SamplerAddressMode::REPEAT` 时，下面的片元着色器会产生下面的图像：
 
 ```glsl
 void main() {
@@ -196,16 +200,16 @@ void main() {
 
 ![](../images/texture_on_square_repeated.png)
 
-You can also manipulate the texture colors using the vertex colors:
+你也可以用顶点颜色来改变纹理颜色：
 
 ```glsl
 void main() {
     outColor = vec4(fragColor * texture(texSampler, fragTexCoord).rgb, 1.0);
 }
 ```
 
-I've separated the RGB and alpha channels here to not scale the alpha channel.
+我在这里分离了 RGB 和 alpha 通道，以免缩放 alpha 通道。
 
 ![](../images/texture_on_square_colorized.png)
 
-You now know how to access images in shaders! This is a very powerful technique when combined with images that are also written to in framebuffers. You can use these images as inputs to implement cool effects like post-processing and camera displays within the 3D world.
+现在你知道如何在着色器中访问图像了！当与帧缓冲中也写入的图像结合使用时，这是一种非常强大的技术。你可以使用这些图像作为输入来实现很酷的效果，比如后处理和 3D 世界中的相机显示。