Input Assemble Stageの指定
Input Assembler Stage
Input Assembler Stageでの処理の記述について調べる。
graphics pipelineのstageの概要は以下に記載。
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Vertex Input State
レンダリングを行うためには、pipelineにデータを入力する必要がある。
データを入力する際に、どのbufferからデータを取ってくるのかを指定するために、vertex indexやinstance indexを使用できる。
VkPipelineVertexInputStateCreateInfo
shaderがデータを扱えるようにvertex inputの情報を記述する。
// Provided by VK_VERSION_1_0
typedef struct VkPipelineVertexInputStateCreateInfo {
VkStructureType sType;
const void* pNext;
VkPipelineVertexInputStateCreateFlags flags;
uint32_t vertexBindingDescriptionCount;
const VkVertexInputBindingDescription* pVertexBindingDescriptions;
uint32_t vertexAttributeDescriptionCount;
const VkVertexInputAttributeDescription* pVertexAttributeDescriptions;
} VkPipelineVertexInputStateCreateInfo;
VertexInputAttributesとVertexInputBindings
VertexInputAttributes : Vertex shader variablesがbufferにどのように存在しているかを表す。variablesがvkbufferにboundされる際に、variablesとVertexInputAttributesのnumberが紐づく。
VertexInputBindings : vertex dataにbufferをbindする。VertexInputAttributesがVertexInputBindingsに紐づき、VertexInputBindingsはvkbufferに紐づく。
Vertex shaders can define input variables, which receive vertex attribute data transferred from one or more VkBuffer(s) by drawing commands. Vertex shader input variables are bound to buffers via an indirect binding where the vertex shader associates a vertex input attribute number with each variable, vertex input attributes are associated to vertex input bindings on a per-pipeline basis, and vertex input bindings are associated with specific buffers on a per-draw basis via the vkCmdBindVertexBuffers command.
Vulkan® 1.2.203 - A Specification (with all registered Vulkan extensions)
VkVertexInputAttributeDescription
vertex bufferにある各vertexに対して、vertex attributeがどこにあるのかを表す。
// Provided by VK_VERSION_1_0
typedef struct VkVertexInputAttributeDescription {
uint32_t location;
uint32_t binding;
VkFormat format;
uint32_t offset;
} VkVertexInputAttributeDescription;
- location is the shader input location number for this attribute.
- binding is the binding number which this attribute takes its data from.
- format is the size and type of the vertex attribute data.
- offset is a byte offset of this attribute relative to the start of an element in the vertex input binding.
location
vertex shader内で使われるindex。locationは連続である必要もなければ、すべてのlocationがパイプライン内で使用される必要もない。binding
どのbufferからbindされているのか、このattributeがどこからデータを取ってくるのかを表す。対応するVkVertexInputBindingDescriptionのbindingと一致する。VkVertexInputBindingDescription
bindしているbufferの詳細を表す。
// Provided by VK_VERSION_1_0
typedef struct VkVertexInputBindingDescription {
uint32_t binding;
uint32_t stride;
VkVertexInputRate inputRate;
} VkVertexInputBindingDescription;
- binding is the binding number that this structure describes.
- stride is the byte stride between consecutive elements within the buffer.
- inputRate is a VkVertexInputRate value specifying whether vertex attribute addressing is a function of the vertex index or of the instance index.
binding
bindのindexを表す。stride
bindされている情報がbufferの先頭からどの距離にあるかを示す(bytes)。inputRate
vertex attributesのデータがvertex indexかinstance indexであるかを指定する。VkPipelineInputAssemblyStateCreateInfo
Drawing can be achieved in two modes:
- Programmable Mesh Shading, the mesh shader assembles primitives, or
- Programmable Primitive Shading, the input primitives are assembled
as follows.
Each draw is made up of zero or more vertices and zero or more instances, which are processed by the device and result in the assembly of primitives. Primitives are assembled according to the pInputAssemblyState member of the VkGraphicsPipelineCreateInfo structure, which is of type VkPipelineInputAssemblyStateCreateInfo:
mesh shading :
Vulkan® 1.2.203 - A Specification (with all registered Vulkan extensions)
primitive shading :
Vulkan® 1.2.203 - A Specification (with all registered Vulkan extensions)
描画には大きく2つのアプローチがあり、
- mesh shading : 図形がmesh shaderでassembleされる(組み立てられる)。
- primitive shading : 頂点やinstanceをもとにassembleされる。
VkPipelineInputAssemblyStateCreateInfoは後者の方法で実行する。
// Provided by VK_VERSION_1_0
typedef struct VkPipelineInputAssemblyStateCreateInfo {
VkStructureType sType;
const void* pNext;
VkPipelineInputAssemblyStateCreateFlags flags;
VkPrimitiveTopology topology;
VkBool32 primitiveRestartEnable;
} VkPipelineInputAssemblyStateCreateInfo;VkPipelineInputAssemblyStateCreateInfo(3)
topology
topology is a VkPrimitiveTopology defining the primitive topology
VkPrimitiveTopology
// Provided by VK_VERSION_1_0
typedef enum VkPrimitiveTopology {
VK_PRIMITIVE_TOPOLOGY_POINT_LIST = 0,
VK_PRIMITIVE_TOPOLOGY_LINE_LIST = 1,
VK_PRIMITIVE_TOPOLOGY_LINE_STRIP = 2,
VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST = 3,
VK_PRIMITIVE_TOPOLOGY_TRIANGLE_STRIP = 4,
VK_PRIMITIVE_TOPOLOGY_TRIANGLE_FAN = 5,
VK_PRIMITIVE_TOPOLOGY_LINE_LIST_WITH_ADJACENCY = 6,
VK_PRIMITIVE_TOPOLOGY_LINE_STRIP_WITH_ADJACENCY = 7,
VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST_WITH_ADJACENCY = 8,
VK_PRIMITIVE_TOPOLOGY_TRIANGLE_STRIP_WITH_ADJACENCY = 9,
VK_PRIMITIVE_TOPOLOGY_PATCH_LIST = 10,
} VkPrimitiveTopology;
primitiveRestartEnable
primitiveRestartEnable controls whether a special vertex index value is treated as restarting the assembly of primitives. This enable only applies to indexed draws (vkCmdDrawIndexed, vkCmdDrawMultiIndexedEXT, and vkCmdDrawIndexedIndirect), and the special index value is either 0xFFFFFFFF when the indexType parameter of vkCmdBindIndexBuffer is equal to VK_INDEX_TYPE_UINT32, 0xFF when indexType is equal to VK_INDEX_TYPE_UINT8_EXT, or 0xFFFF when indexType is equal to VK_INDEX_TYPE_UINT16. Primitive restart is not allowed for “list” topologies, unless one of the features primitiveTopologyPatchListRestart (for VK_PRIMITIVE_TOPOLOGY_PATCH_LIST) or primitiveTopologyListRestart (for all other list topologies) is enabled.
特別なvertex indexで図形のassembleをrestartするかどうかを決める。topoligyがlist系のものでは有効にできない。
| Special Value | IndexType of vkCmdBindIndexBuffer |
|---|---|
| 0xFFFFFFFF | VK_INDEX_TYPE_UINT32 |
| 0xFFFF | VK_INDEX_TYPE_UINT16 |
| 0xFF | VK_INDEX_TYPE_UINT8_EXT |
更新履歴
2022/1/23 Vertex Input State 新規追加
