Descriptors

VkVertexInputBindingDescription :

• structure specifying vertex input binding description.
• Each vertex input binding is specified by the VkVertexInputBindingDescription structure

typedef struct VkVertexInputBindingDescription {
    uint32_t             binding;
    uint32_t             stride;
    VkVertexInputRate    inputRate;
} VkVertexInputBindingDescription;

VkVertexInputAttributeDescription:

• structure specifying vertex input attribute description
• Each vertex input attribute is specified by the VkVertexInputAttributeDescription structure

typedef struct VkVertexInputAttributeDescription {
    uint32_t    location;
    uint32_t    binding;
    VkFormat    format;
    uint32_t    offset;
} VkVertexInputAttributeDescription;

• How to interpret each attribute (like position, color)

How to use

std::vector<VkVertexInputBindingDescription> LveModel::Vertex::getBindDescriptions(){
  std::vector<VkVertexInputBindingDescription> bindingDescriptions(1);
  bindingDescriptions[0].binding = 0;
  bindingDescriptions[0].stride = sizeof(Vertex);
  bindingDescriptions[0].inputRate = VK_VERTEX_INPUT_RATE_VERTEX;
  return bindingDescriptions;
}

std::vector<VkVertexInputAttributeDescription> LveModel::Vertex::getAttributeDescriptions(){
  std::vector<VkVertexInputAttributeDescription> attributeDescriptions(2);
  attributeDescriptions[0].binding = 0;
  attributeDescriptions[0].location = 0;
  attributeDescriptions[0].format = VK_FORMAT_R32G32B32_SFLOAT;
  attributeDescriptions[0].offset = offsetof(Vertex, position);


  attributeDescriptions[1].binding = 0;
  attributeDescriptions[1].location = 1;
  attributeDescriptions[1].format = VK_FORMAT_R32G32B32_SFLOAT;
  attributeDescriptions[1].offset = offsetof(Vertex, color);
  //Calculate the byte offset of color member in the vertex struct
  return attributeDescriptions;
};

for the attribute description, it matches vertex shader (Location matches) (check GLSL Notes)

layout (location = 0) in vec3 position;
layout (location = 1) in vec3 color;

• binding refers to which vertex buffer this attribute should read from , currently we only have one vertex buffer, and all vertex data stored here