Vulkan：几何着色器的 VkVertexInputBindingDescription 总是错误的

Question

我正在尝试在几何着色器中实现广告牌四边形来渲染粒子效果。几何着色器的输入是点 (vec3)，它的输出是一个带有位置和 UV 坐标 (vec3, vec2) 的三角形带。我尝试了两种顶点输入绑定变体，但都不起作用。

如果我这样设置顶点绑定：

VkVertexInputBindingDescription binding_desc[2] = {};
binding_desc[0].binding = 0;
binding_desc[0].stride = sizeof(glm::vec3);
binding_desc[0].inputRate = VK_VERTEX_INPUT_RATE_VERTEX;

binding_desc[1].binding = 1;
binding_desc[1].stride = sizeof(glm::vec2);
binding_desc[1].inputRate = VK_VERTEX_INPUT_RATE_VERTEX;

VkVertexInputAttributeDescription attribute_desc[2] = {};
attribute_desc[0].location = 0;
attribute_desc[0].binding = binding_desc[0].binding;
attribute_desc[0].format = VK_FORMAT_R32G32B32_SFLOAT;
attribute_desc[0].offset = offsetof(vert_shader_vertex, pos);

attribute_desc[1].location = 1;
attribute_desc[1].binding = binding_desc[1].binding;
attribute_desc[1].format = VK_FORMAT_R32G32_SFLOAT;
attribute_desc[1].offset = offsetof(vert_shader_vertex, uv);

调用 vkCmdDraw 时出现以下错误：

ERROR [default] DS: (OBJECT 0) (CODE 24) The Pipeline State Object (0x3c) expects that this Command Buffer's vertex binding Index 1 should be set via vkCmdBindVertexBuffers. This is because VkVertexInputBindingDescription struct at index 1 of pVertexBindingDescriptions has a binding value of 1.

但是，如果我这样设置：

VkVertexInputBindingDescription binding_desc[1] = {};
binding_desc[0].binding = 0;
binding_desc[0].stride = sizeof(glm::vec3);
binding_desc[0].inputRate = VK_VERTEX_INPUT_RATE_VERTEX;

VkVertexInputAttributeDescription attribute_desc[1] = {};
attribute_desc[0].location = 0;
attribute_desc[0].binding = binding_desc[0].binding;
attribute_desc[0].format = VK_FORMAT_R32G32B32_SFLOAT;
attribute_desc[0].offset = offsetof(vert_shader_vertex, pos);

调用 vkCreateGraphicsPipelines 时出现此错误：

ERROR [default] SC: (OBJECT 0) (CODE 3) Vertex shader consumes input at location 1 but not provided

VkVertexInputBindingDescription 描述的是几何着色器或顶点着色器的输入吗？
我需要 "dummy" 顶点缓冲区中的 UV 坐标作为占位符吗？
会不会是我的几何着色器没有激活，如何确认？
这两种方法中哪一种是正确的，我该如何解决相应的错误？
顺便说一句，我是 Vulkan 的新手，所以欢迎对着色器发表评论。

几何着色器

#version 450

#extension GL_ARB_separate_shader_objects : enable
#extension GL_ARB_shading_language_420pack : enable

layout (points) in;
layout (triangle_strip, max_vertices = 4) out;

layout (location = 0) in vec3 inPos[];

layout (location = 0) out vec3 outPos;
layout (location = 1) out vec2 outUV;

layout (push_constant) uniform constants_t {
    vec3 up;
    vec3 right;
    mat4x4 world;
    mat4x4 projection;
} constants;

void main(void)
{
    const vec3 pos = gl_in[0].gl_Position.xyz;
    const vec3 up = constants.up;
    const vec3 right = constants.right;

    outPos = pos + up - right;
    outUV = vec2(0, 0);
    EmitVertex();

    outPos = pos + up + right;
    outUV = vec2(1, 0);
    EmitVertex();

    outPos = pos - up - right;
    outUV = vec2(0, 1);
    EmitVertex();

    outPos = pos - up + right;
    outUV = vec2(1, 1);
    EmitVertex();

    EndPrimitive();
}

顶点着色器

#version 450

#extension GL_ARB_separate_shader_objects : enable
#extension GL_ARB_shading_language_420pack : enable

layout (location = 0) in vec3 inPos;
layout (location = 1) in vec2 inUV;

layout (location = 0) out vec4 outPos;
layout (location = 1) out vec2 outUV;

layout (push_constant) uniform constants_t {
    vec3 up;
    vec3 right;
    mat4x4 world;
    mat4x4 projection;
} constants;

void main(void) {
    outUV = inUV;
    outPos = vec4(inPos.xyz, 1.0) * constants.world * constants.projection;
}

vkCmdBindVertexBuffers

VkBuffer vertex_buffers[1] = {vertexBuffer};
VkDeviceSize vertex_offset[1] = {0};
vkCmdBindVertexBuffers(commandBuffer, 0, 1, vertex_buffers, vertex_offset);

Answer 1

vkCmdBindVertexBuffers(commandBuffer, 0, 1, vertex_buffers, vertex_offset);

这表示您将一个缓冲区绑定到索引 0。但是您在创建管道时告诉管道您将绑定两个缓冲区。

不要对 Vulkan 撒谎； 它总是知道（当您使用验证层时 ;)）。

您很可能打算让两个顶点属性都使用相同的 缓冲区对象。我从您使用 offsetof 计算它们的相对偏移量这一事实推断出这一点。如果那是你的意图，那么你应该有两个顶点属性使用 相同的缓冲区绑定。

Does the VkVertexInputBindingDescription describe the input to the geometry shader, or the vertex shader?

它无法描述 GS 的输入，因为第一个管线着色器阶段是 顶点着色器。并且创建没有 VS 的图形管道是不可能的。

Vulkan：几何着色器的 VkVertexInputBindingDescription 总是错误的

Vulkan: VkVertexInputBindingDescription always wrong with geometry shader

vertex-buffer

geometry-shader

vulkan

几何着色器

顶点着色器

vkCmdBindVertexBuffers