在使用C#进行Vulkan教程时,我到了应该开始使用Uniform缓冲区的地方(你可以在这里找到该教程)。 首先让我展示相关代码,然后解释问题。我有几个相关结构体:
unsafe struct Buffer
{
public SharpVulkan.Buffer buffer;
public DeviceMemory memory;
public readonly ulong size;
public Buffer(ulong size) : this()
{
this.size = size;
}
public void Destroy(Device device)
{
device.DestroyBuffer(buffer);
device.FreeMemory(memory);
}
}
struct MVPMatrices
{
public static MVPMatrices Identity { get; } = new MVPMatrices { model = Matrix4x4.Identity, view = Matrix4x4.Identity, projection = Matrix4x4.Identity };
public Matrix4x4 model;
public Matrix4x4 view;
public Matrix4x4 projection;
}
struct UniformBuffer
{
public Buffer buffer;
public DescriptorSet descriptorSet;
public void Destroy(Device device)
{
buffer.Destroy(device);
}
}
我认为它们都很容易理解,但如果你需要更多信息,我可以更新问题。 接下来,在主程序中,我创建了几个相关的字段:
static DescriptorSetLayout descriptorSetLayout;
static DescriptorPool descriptorPool;
static UniformBuffer mvpMatricesBuffer;
static readonly MVPMatrices[] mvpMatricesArray = new MVPMatrices[1];
static ref MVPMatrices MVPMatrices => ref mvpMatricesArray[0];
以下是我为缓冲区编写的一些实用方法:
static Buffer CreateBuffer(ulong size, BufferUsageFlags usage, MemoryPropertyFlags memoryPropertyFlags = MemoryPropertyFlags.HostVisible | MemoryPropertyFlags.HostCoherent)
{
Buffer buffer = new Buffer(size);
BufferCreateInfo createInfo = new BufferCreateInfo
{
StructureType = StructureType.BufferCreateInfo,
SharingMode = SharingMode.Exclusive,
Size = size,
Usage = usage,
};
buffer.buffer = logicalDevice.CreateBuffer(ref createInfo);
logicalDevice.GetBufferMemoryRequirements(buffer.buffer, out MemoryRequirements memoryRequirements);
physicalDevice.GetMemoryProperties(out PhysicalDeviceMemoryProperties memoryProperties);
uint memoryTypeIndex = 0;
for (uint i = 0; i < memoryProperties.MemoryTypeCount; i++)
{
MemoryType* memoryType = &memoryProperties.MemoryTypes.Value0 + i;
if ((memoryRequirements.MemoryTypeBits & (1 << (int)i)) != 0 && memoryType->PropertyFlags.HasFlag(memoryPropertyFlags))
{
memoryTypeIndex = i;
break;
}
}
MemoryAllocateInfo allocateInfo = new MemoryAllocateInfo
{
StructureType = StructureType.MemoryAllocateInfo,
AllocationSize = memoryRequirements.Size,
MemoryTypeIndex = memoryTypeIndex,
};
buffer.memory = logicalDevice.AllocateMemory(ref allocateInfo);
logicalDevice.BindBufferMemory(buffer.buffer, buffer.memory, 0);
return buffer;
}
static void SetBufferData<T>(this Buffer buffer, T[] data)
where T : struct
{
ulong size = (ulong)(Marshal.SizeOf<T>() * data.Length);
if (size != buffer.size)
throw new ArgumentException("Size of buffer data must be the same as the size of the buffer!");
IntPtr memory = logicalDevice.MapMemory(buffer.memory, 0, size, MemoryMapFlags.None);
System.Buffer.MemoryCopy(Marshal.UnsafeAddrOfPinnedArrayElement(data, 0).ToPointer(), memory.ToPointer(), (uint)size, (uint)size);
logicalDevice.UnmapMemory(buffer.memory);
}
static T[] GetBufferData<T>(this Buffer buffer)
where T : struct
{
T[] result = new T[(int)buffer.size / Marshal.SizeOf<T>()];
IntPtr memory = logicalDevice.MapMemory(buffer.memory, 0, buffer.size, MemoryMapFlags.None);
System.Buffer.MemoryCopy(memory.ToPointer(), Marshal.UnsafeAddrOfPinnedArrayElement(result, 0).ToPointer(), (uint)buffer.size, (uint)buffer.size);
logicalDevice.UnmapMemory(buffer.memory);
return result;
}
static DescriptorSet AllocateDescriptorSet()
{
DescriptorSetLayout* setLayout = stackalloc DescriptorSetLayout[1];
*setLayout = descriptorSetLayout;
DescriptorSetAllocateInfo allocateInfo = new DescriptorSetAllocateInfo
{
StructureType = StructureType.DescriptorSetAllocateInfo,
DescriptorPool = descriptorPool,
DescriptorSetCount = 1,
SetLayouts = (IntPtr)setLayout,
};
DescriptorSet set = DescriptorSet.Null;
logicalDevice.AllocateDescriptorSets(ref allocateInfo, &set);
return set;
}
static UniformBuffer CreateUniformBuffer(ulong size, uint binding)
{
UniformBuffer buffer = new UniformBuffer
{
buffer = CreateBuffer(size, BufferUsageFlags.UniformBuffer),
descriptorSet = AllocateDescriptorSet(),
};
DescriptorBufferInfo bufferInfo = new DescriptorBufferInfo
{
Buffer = buffer.buffer.buffer,
Offset = 0,
Range = buffer.buffer.size,
};
WriteDescriptorSet descriptorWrite = new WriteDescriptorSet
{
StructureType = StructureType.WriteDescriptorSet,
BufferInfo = new IntPtr(&bufferInfo),
DescriptorCount = 1,
DescriptorType = DescriptorType.UniformBuffer,
DestinationArrayElement = 0,
DestinationBinding = binding,
DestinationSet = buffer.descriptorSet,
ImageInfo = IntPtr.Zero,
TexelBufferView = IntPtr.Zero,
};
logicalDevice.UpdateDescriptorSets(1, &descriptorWrite, 0, null);
return buffer;
}
一开始我也用一个值初始化了它,但是我做了Get/SetBufferData方法,这样我就可以每帧更新数据。这里是在渲染之前在主循环中调用的函数:
static void UpdateApplication()
{
MVPMatrices.model = Matrix4x4.Identity;
MVPMatrices.view = Matrix4x4.Identity;
MVPMatrices.projection = Matrix4x4.Identity;
mvpMatricesBuffer.buffer.SetBufferData(mvpMatricesArray);
Console.WriteLine(mvpMatricesBuffer.buffer.GetBufferData<MVPMatrices>()[0].model);
Console.WriteLine(mvpMatricesBuffer.buffer.GetBufferData<MVPMatrices>()[0].view);
Console.WriteLine(mvpMatricesBuffer.buffer.GetBufferData<MVPMatrices>()[0].projection);
}
还有一个函数是用于分配命令缓冲区的。不需要展示整个过程,但基本上:我分配缓冲区,绑定一些缓冲区并进行绘制。在绘制之前,我将描述符集绑定到命令缓冲区,所以这是我使用的代码(你只需要知道"buffer"是指向命令缓冲区的指针):
DescriptorSet* descriptorSets = stackalloc DescriptorSet[1];
*descriptorSets = mvpMatricesBuffer.descriptorSet;
buffer->BindDescriptorSets(PipelineBindPoint.Graphics, pipelineLayout, 0, 1, descriptorSets, 0, null);
现在有两个着色器。唯一相关的着色器是顶点着色器,因此在这里:
#version 450
#extension GL_ARB_separate_shader_objects : enable
layout(binding = 0) uniform MVPMatrices
{
mat4 model;
mat4 view;
mat4 projection;
} mvpMatrices;
layout(location = 0) in vec3 position;
layout(location = 1) in vec4 color;
layout(location = 0) out vec4 vertexColor;
void main()
{
gl_Position = mvpMatrices.projection * mvpMatrices.view * mvpMatrices.model * vec4(position, 1);
vertexColor = color;
}
那么问题是什么?与图形一样:它没有渲染。每当我删除通过矩阵相乘的部分时,它就可以正常工作。我还尝试将颜色设置为模型矩阵的第二行(应该是绿色),但它并没有起作用。
在更新方法中显示的日志打印出矩阵缓冲区的数据,它们都是单位矩阵(就像它们应该的那样)。这意味着缓冲区的数据是正确的。
然而,描述符集是另一回事。如果我不将集布局绑定到管线布局,则会出现错误,指出着色器使用了描述符槽,但在管线布局中没有声明。这意味着集布局被正确地绑定。
如果我不创建描述符集,那么当我将其绑定到命令缓冲区时,我会收到一个错误。这意味着描述符集被正确创建,因此描述符池也正常(否则我会收到错误)。
因此,缓冲区和描述符集都有效。这让我得出一个结论:缓冲区和描述符集没有正确链接。奇怪的是,连接两者的代码是Device.UpdateDescriptorSets调用。问题在于,如果我不将缓冲区信息传递给DescriptorWrite变量,或者如果我向缓冲区信息传递空句柄,我会收到一个错误,指出描述符集从未被更新过。如果我不将描述符集传递给DescriptorWrite变量,那么情况也是一样的。这意味着它知道我正在更新它,知道我正在发送缓冲区,但数据仍然无法发送到着色器。
尝试调试了一个星期后,我可以说,对我来说一切看起来都很完美,我不知道问题在哪里。这让我感到绝望,所以我来到这里。
这是我在网站上的第一篇帖子,我不知道是否提供了您所需的所有信息(即使我感觉提供太多了),因此,如果帖子有任何问题,请告诉我,我会尝试解决。