vertexattributes

Vertex attributes

Synopsis

This sample demonstrates two different ways of providing vertex data to the GPU using either interleaved or separate buffers for vertex attributes.

Shader interface

The shader interface for passing the vertex attributes is the same, no matter if the data provided is coming from a single interleaved or multiple separate buffers.

layout (location = 0) in vec3 inPos;
layout (location = 1) in vec3 inNormal;
layout (location = 2) in vec2 inUV;
layout (location = 3) in vec4 inTangent;

Interleaved vertex attributes

In an interleaved vertex buffer, the components that make up a single vertex are stored after each other, so the stride of a single vertex is the sum of it's component's sizes.

// Binding
const std::vector<VkVertexInputBindingDescription> vertexInputBindingsInterleaved = {
    { 0, sizeof(Vertex), VK_VERTEX_INPUT_RATE_VERTEX },
};

// Attribute
const std::vector<VkVertexInputAttributeDescription> vertexInputAttributesInterleaved = {
    { 0, 0, VK_FORMAT_R32G32B32_SFLOAT, offsetof(Vertex, pos) },
    { 1, 0, VK_FORMAT_R32G32B32_SFLOAT, offsetof(Vertex, normal) },
    { 2, 0, VK_FORMAT_R32G32_SFLOAT, offsetof(Vertex, uv) },
    { 3, 0, VK_FORMAT_R32G32B32A32_SFLOAT, offsetof(Vertex, tangent) },
};

Separate vertex attributes

When using separate buffers, each component is stored in it's own buffer. So e.g. the position buffer only contains vertex positions stored consecutively.

// Bindings
const std::vector<VkVertexInputBindingDescription> vertexInputBindingsSeparate = {
    { 0, sizeof(glm::vec3), VK_VERTEX_INPUT_RATE_VERTEX },
    { 1, sizeof(glm::vec3), VK_VERTEX_INPUT_RATE_VERTEX },
    { 2, sizeof(glm::vec2), VK_VERTEX_INPUT_RATE_VERTEX },
    { 3, sizeof(glm::vec4), VK_VERTEX_INPUT_RATE_VERTEX },
};

// Attributes
const std::vector<VkVertexInputAttributeDescription> vertexInputAttributesSeparate = {
    { 0, 0, VK_FORMAT_R32G32B32_SFLOAT, 0 },
    { 1, 1, VK_FORMAT_R32G32B32_SFLOAT, 0 },
    { 2, 2, VK_FORMAT_R32G32_SFLOAT, 0 },
    { 3, 3, VK_FORMAT_R32G32B32A32_SFLOAT, 0 },
};