Multisampling (quality/multisampling.md) (#82)

Co-authored-by: Cousin Ze <2571851049@qq.com>
Co-authored-by: 梦飞翔 <1149761294@qq.com>

TERMINOLOGY.csv

@@ -114,6 +114,8 @@ stencil,名词,计算机图形学术语,模板,,,
 oversampling,名词,计算机图形学术语,（纹理）采样过密,指的是采样操作相对纹理上的纹素数量过密,,
 undersampling,名词,计算机图形学术语,（纹理）采样过疏,,,
 anisotropic filtering,名词,计算机图形学术语,各向异性过滤,,,
+level of detail,名词,计算机图形学术语,细节级别,,,
+lod,名词,计算机图形学术语,细节级别,和 level of detail 一样,,
 ,,,,,,
 normal,名词,数学概念,法向量/法线,,,
 component,名词,数学概念,（向量的）分量,例如一个四维向量有 x y z t 四个分量,,

book/src/SUMMARY.md

@@ -63,7 +63,7 @@
 # 渲染质量
 
 - [生成多级渐远](./quality/generating_mipmaps.md)
-- [Multisampling](./quality/multisampling.md)
+- [多重采样](./quality/multisampling.md)
 
 # 动态场景
 

book/src/quality/multisampling.md

@@ -1,28 +1,43 @@
-# Multisampling
+# 多重采样
 
-**Code:** [main.rs](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/src/29_multisampling.rs)
+> 原文链接：<https://kylemayes.github.io/vulkanalia/quality/multisampling.html>
+>
+> Commit Hash: 72b9244ea1d53fa0cf40ce9dbf854c43286bf745
+
+**本章代码:** [main.rs](https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/tree/master/src/29_multisampling.rs)
 
 Our program can now load multiple levels of detail for textures which fixes artifacts when rendering objects far away from the viewer. The image is now a lot smoother, however on closer inspection you will notice jagged saw-like patterns along the edges of drawn geometric shapes. This is visible in one of our early programs when we rendered a quad:
 
+现在我们的程序为纹理加载了多个细节级别，这能修复渲染远离观察者的物体时的伪影。图像现在更加平滑了，但是如果仔细观察，你会发现在几何形状的边缘有锯齿状的图案。这在我们早期的程序中就能看到，当我们渲染一个四边形时：
+
 ![](../images/texcoord_visualization.png)
 
 This undesired effect is called "aliasing" and it's a result of a limited numbers of pixels that are available for rendering. Since there are no displays out there with unlimited resolution, it will be always visible to some extent. There's a number of ways to fix this and in this chapter we'll focus on one of the more popular ones: [multisample anti-aliasing](https://en.wikipedia.org/wiki/Multisample_anti-aliasing) (MSAA).
 
+这种我们不希望看到的效果被称为“锯齿”（aliasing），它是由于渲染可用的像素数量有限造成的。因为没有显示器的分辨率是无限的，所以锯齿总是会在某种程度上可见。有很多方法可以修复这个问题，在本章中我们将会专注于其中一个比较流行的方法：[多重采样抗锯齿](https://en.wikipedia.org/wiki/Multisample_anti-aliasing)（multisample anti-aliasing, MSAA）。
+
 In ordinary rendering, the pixel color is determined based on a single sample point which in most cases is the center of the target pixel on screen. If part of the drawn line passes through a certain pixel but doesn't cover the sample point, that pixel will be left blank, leading to the jagged "staircase" effect.
 
+在通常的渲染中，像素的颜色是由单个样本点决定的，这个样本点在大多数情况下是屏幕上目标像素的中心。而如果绘制的线段通过某个像素，但是没有覆盖样本点，那么这个像素就会被留空，导致了锯齿状的“楼梯”效果。
+
 ![](../images/aliasing.png)
 
 What MSAA does is it uses multiple sample points per pixel (hence the name) to determine its final color. As one might expect, more samples lead to better results, however it is also more computationally expensive.
 
+MSAA 所做的就是使用多个样本点来决定像素的最终颜色（因此得名）。正如你所期望的那样，更多的样本会得到更好的结果，但也会消耗更多计算资源。
+
 ![](../images/antialiasing.png)
 
 In our implementation, we will focus on using the maximum available sample count. Depending on your application this may not always be the best approach and it might be better to use less samples for the sake of higher performance if the final result meets your quality demands.
 
+在我们的实现中，我们会使用可用的最大样本数量。取决于你的应用程序，这可能不是最好的方法。如果更少的样本就能满足你的质量要求，那么为了性能，使用更少的样本可能会更好。
 
-## Getting available sample count
+## 获取可用的样本数量
 
 Let's start off by determining how many samples our hardware can use. Most modern GPUs support at least 8 samples but this number is not guaranteed to be the same everywhere. We'll keep track of it by adding a new field to `AppData`:
 
+让我们从检测硬件支持多少样本开始。大多数现代 GPU 至少支持 8 个样本，但这个数字不保证在任何地方都是一样的。我们在 `AppData` 中添加一个新字段来记录它：
+
 ```rust,noplaypen
 struct AppData {
     // ...
@@ -34,6 +49,8 @@ struct AppData {
 
 By default we'll be using only one sample per pixel which is equivalent to no multisampling, in which case the final image will remain unchanged. The exact maximum number of samples can be extracted from `vk::PhysicalDeviceProperties` associated with our selected physical device. We're using a depth buffer, so we have to take into account the sample count for both color and depth. The highest sample count that is supported by both (&) will be the maximum we can support. Add a function that will fetch this information for us:
 
+默认情况下，我们为每个像素使用一个样本，相当于没有多重采样，这种情况下最终图像将保持不变。最大样本数可以从与我们选择的物理设备相关联的 `vk::PhysicalDeviceProperties` 中提取。我们使用了深度缓冲，因此我们必须考虑将颜色和深度的样本数都考虑在内。两者都支持的最高样本数（使用 `&` 运算符）将是我们可以支持的最大样本数。添加一个函数来获取这些信息：
+
 ```rust,noplaypen
 unsafe fn get_max_msaa_samples(
     instance: &Instance,
@@ -59,6 +76,8 @@ unsafe fn get_max_msaa_samples(
 
 We will now use this function to set the `msaa_samples` variable during the physical device selection process. For this, we have to slightly modify the `pick_physical_device` function to set the maximum MSAA samples after selecting a physical device:
 
+现在我们在选取物理设备的环节使用这个函数来设置 `msaa_samples` 变量。我们稍微修改 `pick_physical_device` 函数，在选取物理设备之后设置最大的 MSAA 样本数：
+
 ```rust,noplaypen
 unsafe fn pick_physical_device(instance: &Instance, data: &mut AppData) -> Result<()> {
     // ...
@@ -79,10 +98,13 @@ unsafe fn pick_physical_device(instance: &Instance, data: &mut AppData) -> Resul
 }
 ```
 
-## Setting up a render target
+## 设置渲染目标
 
 In MSAA, each pixel is sampled in an offscreen buffer which is then rendered to the screen. This new buffer is slightly different from regular images we've been rendering to - they have to be able to store more than one sample per pixel. Once a multisampled buffer is created, it has to be resolved to the default framebuffer (which stores only a single sample per pixel). This is why we have to create an additional render target and modify our current drawing process. We only need one render target since only one drawing operation is active at a time, just like with the depth buffer. Add the following `AppData` fields:
 
+<!-- 和这里 https://github.com/chuigda/Vulkan-Tutorial-Rust-CN/pull/74#discussion_r1341886973 一样，真的只有一个绘制操作处于活动状态吗？ -->
+在 MSAA 中，每个像素都在一个离屏缓冲中进行采样，然后离屏缓冲被渲染到屏幕上。这个新的缓冲与我们一直渲染到的普通图像略有不同 —— 它们必须能为每个像素存储多个样本。一旦创建了多重采样缓冲，就必须将其解析到默认的帧缓冲（每个像素只存储一个样本）。这就是为什么我们必须创建一个额外的渲染目标并修改我们当前的绘制过程。我们只需要一个渲染目标，因为一次只能有一个绘制操作处于活动状态，就像深度缓冲一样。在 `AppData` 中添加以下字段：
+
 ```rust,noplaypen
 struct AppData {
     // ...
@@ -95,6 +117,8 @@ struct AppData {
 
 This new image will have to store the desired number of samples per pixel, so we need to pass this number to `vk::ImageCreateInfo` during the image creation process. Modify the `^create_image` function by adding a `samples` parameter:
 
+这个新的图像需要为每个像素存储所需数量的样本，因此我们需要在创建图像的过程中将样本数传递给 `vk::ImageCreateInfo`。修改 `create_image` 函数，添加一个 `samples` 参数：
+
 ```rust,noplaypen
 unsafe fn create_image(
     instance: &Instance,
@@ -122,6 +146,8 @@ unsafe fn create_image(
 
 For now, update all calls to this function using `vk::SampleCountFlags::_1` - we will be replacing this with proper values as we progress with implementation:
 
+现在我们先暂时给所有调用这个函数的地方传递 `vk::SampleCountFlags::_1`，我们将在实现过程中逐步将其替换为正确的值：
+
 ```rust,noplaypen
 let (depth_image, depth_image_memory) = create_image(
     instance,
@@ -158,6 +184,8 @@ let (texture_image, texture_image_memory) = create_image(
 
 We will now create a multisampled color buffer. Add a `create_color_objects` function and note that we're using `msaaSamples` here as a function parameter to `createImage`. We're also using only one mip level, since this is enforced by the Vulkan specification in case of images with more than one sample per pixel. Also, this color buffer doesn't need mipmaps since it's not going to be used as a texture:
 
+现在我们将创建一个多重采样的颜色缓冲区。添加一个 `create_color_objects` 函数，并注意我们在这里将 `data.msaa_samples` 传递给 `create_image`。我们只使用一个多级渐远级别，因为 Vulkan 规范要求每个像素有多个样本的图像必须只有一个多级渐远级别。此外，这个颜色缓冲区不需要多级渐远级别，因为它不会被用作纹理：
+
 ```rust,noplaypen
 unsafe fn create_color_objects(
     instance: &Instance,
@@ -196,6 +224,8 @@ unsafe fn create_color_objects(
 
 For consistency, call the function right before `create_depth_objects`:
 
+为了保持一致性，在 `create_depth_objects` 之前调用这个函数：
+
 ```rust,noplaypen
 unsafe fn create(window: &Window) -> Result<Self> {
     // ...
@@ -207,6 +237,8 @@ unsafe fn create(window: &Window) -> Result<Self> {
 
 Now that we have a multisampled color buffer in place it's time to take care of depth. Modify `create_depth_objects` and update the number of samples used by the depth buffer:
 
+现在我们已经有了一个多重采样的颜色缓冲区，是时候来处理深度了。修改 `create_depth_objects`，更新深度缓冲区使用的样本数：
+
 ```rust,noplaypen
 unsafe fn create_depth_objects(
     instance: &Instance,
@@ -235,6 +267,8 @@ unsafe fn create_depth_objects(
 
 We have now created a couple of new Vulkan resources, so let's not forget to release them when necessary:
 
+我们现在创建了一些新的 Vulkan 资源，所以不要忘记在必要时释放它们：
+
 ```rust,noplaypen
 unsafe fn destroy_swapchain(&mut self) {
     self.device.destroy_image_view(self.data.color_image_view, None);
@@ -246,6 +280,8 @@ unsafe fn destroy_swapchain(&mut self) {
 
 And update the `App::recreate_swapchain` method so that the new color image can be recreated in the correct resolution when the window is resized:
 
+然后更新 `App::recreate_swapchain` 方法，这样当窗口大小改变时，新的颜色图像就能以正确的分辨率重新创建：
+
 ```rust,noplaypen
 unsafe fn recreate_swapchain(&mut self, window: &Window) -> Result<()> {
     // ...
@@ -257,10 +293,14 @@ unsafe fn recreate_swapchain(&mut self, window: &Window) -> Result<()> {
 
 We made it past the initial MSAA setup, now we need to start using this new resource in our graphics pipeline, framebuffer, render pass and see the results!
 
-## Adding new attachments
+我们已经完成了初始的 MSAA 设置，现在我们需要在图形管线、帧缓冲和渲染流程中开始使用这个新资源，然后看看效果！
+
+## 添加新的附件
 
 Let's take care of the render pass first. Modify `^create_render_pass` and update color and depth attachment creation info structs:
 
+首先处理渲染流程。修改 `create_render_pass`，更新颜色和深度附件创建信息：
+
 ```rust,noplaypen
 unsafe fn create_render_pass(
     instance: &Instance,
@@ -284,6 +324,8 @@ unsafe fn create_render_pass(
 
 You'll notice that we have changed the finalLayout from `vk::ImageLayout::PRESENT_SRC_KHR` to `vk::ImageLayout::COLOR_ATTACHMENT_OPTIMAL`. That's because multisampled images cannot be presented directly. We first need to resolve them to a regular image. This requirement does not apply to the depth buffer, since it won't be presented at any point. Therefore we will have to add only one new attachment for color which is a so-called resolve attachment:
 
+你会注意到我们已经将 `final_layout` 从 `vk::ImageLayout::PRESENT_SRC_KHR` 改为了 `vk::ImageLayout::COLOR_ATTACHMENT_OPTIMAL`。这是因为多重采样图像不能直接呈现。我们首先需要将它们解析为普通图像。这个要求不适用于深度缓冲区，因为它不会在任何时候被呈现。因此，我们只需要为颜色添加一个新的附件，这是一个所谓的解析附件：
+
 ```rust,noplaypen
 let color_resolve_attachment = vk::AttachmentDescription::builder()
     .format(data.swapchain_format)
@@ -298,6 +340,8 @@ let color_resolve_attachment = vk::AttachmentDescription::builder()
 
 The render pass now has to be instructed to resolve multisampled color image into regular attachment. Create a new attachment reference that will point to the color buffer which will serve as the resolve target:
 
+现在必须告诉渲染流程将多重采样的颜色图像解析为普通附件。创建一个新的附件引用，它将指向颜色缓冲区，该缓冲区将用作解析目标：
+
 ```rust,noplaypen
 let color_resolve_attachment_ref = vk::AttachmentReference::builder()
     .attachment(2)
@@ -306,6 +350,8 @@ let color_resolve_attachment_ref = vk::AttachmentReference::builder()
 
 Set the `resolve_attachments` subpass struct member to point to the newly created attachment reference. This is enough to let the render pass define a multisample resolve operation which will let us render the image to screen:
 
+让 `resolve_attachments` 成员指向新创建的附件引用。这就足以让渲染流程定义一个能将图像渲染到屏幕上的多重采样解析操作了：
+
 ```rust,noplaypen
 let color_attachments = &[color_attachment_ref];
 let resolve_attachments = &[color_resolve_attachment_ref];
@@ -318,6 +364,8 @@ let subpass = vk::SubpassDescription::builder()
 
 Now update render pass info struct with the new color attachment:
 
+现在用新的颜色附件更新渲染流程创建信息：
+
 ```rust,noplaypen
 let attachments = &[
     color_attachment,
@@ -334,12 +382,16 @@ let info = vk::RenderPassCreateInfo::builder()
 
 With the render pass in place, modify `create_framebuffers` and add the new image view to the attachments slice:
 
+渲染流程就位了，修改 `create_framebuffers`，将新的图像视图添加到附件切片中：
+
 ```rust,noplaypen
 let attachments = &[data.color_image_view, data.depth_image_view, *i];
 ```
 
 Finally, tell the newly created pipeline to use more than one sample by modifying `^create_pipeline`:
 
+最后，修改 `create_pipeline` 来告诉新创建的管线使用多个样本：
+
 ```rust,noplaypen
 let multisample_state = vk::PipelineMultisampleStateCreateInfo::builder()
     .sample_shading_enable(false)
@@ -348,20 +400,28 @@ let multisample_state = vk::PipelineMultisampleStateCreateInfo::builder()
 
 Now run your program and you should see the following:
 
+现在运行程序，你应该会看到下面的效果：
+
 ![](../images/multisampling.png)
 
 Just like with mipmapping, the difference may not be apparent straight away. On a closer look you'll notice that the edges are not as jagged anymore and the whole image seems a bit smoother compared to the original (again it will be much easier to spot differences if you open the below image in a separate tab).
 
+就像多级渐远级别一样，差异可能不会立即显现出来。仔细观察，你会注意到边缘不再那么锯齿状，整个图像与原始图像相比似乎更加平滑（如果你在单独的标签页中打开下面的图像，差异会更容易被发现）。
+
 ![](../images/multisampling_comparison.png)
 
 The difference is more noticeable when taking another close look at the axe head at 8x magnification:
 
+再把斧头头部放大 8 倍，差异更加明显：
+
 ![](../images/multisampling_comparison_axe.png)
 
-## Quality improvements
+## 质量提升
 
 There are certain limitations of our current MSAA implementation which may impact the quality of the output image in more detailed scenes. For example, we're currently not solving potential problems caused by shader aliasing, i.e. MSAA only smoothens out the edges of geometry but not the interior filling. This may lead to a situation when you get a smooth polygon rendered on screen but the applied texture will still look aliased if it contains high contrasting colors. One way to approach this problem is to enable [Sample Shading](https://www.khronos.org/registry/vulkan/specs/1.0/html/vkspec.html#primsrast-sampleshading) which will improve the image quality even further, though at an additional performance cost:
 
+我们目前的 MSAA 实现有一些局限性，在细节更多的场景中，这可能影响输出画面的质量。例如，现在我们还没有解决着色器锯齿会造成的潜在问题，也就是说，MSAA 只平滑了图形的边缘，但却没有处理内部的填充。这可能会导致这样一种情况：屏幕上渲染出了一个平滑的多边形，但是如果应用的纹理包含高对比度的颜色，那么纹理看起来仍然是锯齿状的。解决这个问题的一种方法是启用[采样着色](https://www.khronos.org/registry/vulkan/specs/1.0/html/vkspec.html#primsrast-sampleshading)，这将进一步提高图像质量，但会带来额外的性能开销：
+
 ```rust,noplaypen
 unsafe fn create_logical_device(
     instance: &Instance,
@@ -395,4 +455,6 @@ unsafe fn create_pipeline(device: &Device, data: &mut AppData) -> Result<()> {
 
 In this example we'll leave sample shading disabled but in certain scenarios the quality improvement may be noticeable:
 
+在这个例子中，我们将采样着色保持禁用。但在某些情况下，采样着色可以带来显著的质量提升：
+
 ![](../images/sample_shading.png)