The VK_EXT_multi_draw Vulkan extension was recently released and closes an existing gap between the OpenGL and Vulkan APIs. It can be used to improve the performance of some Vulkan apps and as a tool when implementing OpenGL on top of Vulkan as Zink does. In this talk Ricardo Garcia will give a quick overview of the extension. (c) X.Org Developer Conference (XDC) 2021 Sep 15 - 17, 2021 http://xdc2021.x.org

1. Quick Overview of
VK_EXT_multi_draw
Ricardo Garcia
XDC 2021

2. Quick Overview of VK_EXT_multi_draw
Ricardo Garcia, XDC 2021
VK_EXT_multi_draw is...
 An extension to cover an existing gap between OpenGL and Vulkan
●
glMultiDrawArrays
●
glMultiDrawElements
 Created by Mike Blumenkrantz (Valve) to use it in Zink
 Can be useful for more people/scenarios
 Allows recording multiple draw calls without changing state and avoids CPU
overhead caused by command buffer state checks
 Similar to the “indirect” draw calls but without using GPU-accessible memory

3. Quick Overview of VK_EXT_multi_draw
Ricardo Garcia, XDC 2021
VK_EXT_multi_draw adds...
 vkCmdDrawMultiEXT (multiple vkCmdDraw calls)
●
VkMultiDrawInfoEXT structure
 vkCmdDrawMultiIndexedEXT (multiple vkCmdDrawIndexed calls)
●
VkMultiDrawIndexedInfoEXT structure

4. void vkCmdDraw(
VkCommandBuffer commandBuffer,
uint32_t vertexCount ,
uint32_t instanceCount,
uint32_t firstVertex ,
uint32_t firstInstance);
Quick Overview of VK_EXT_multi_draw
Ricardo Garcia, XDC 2021
vertexCount
firstVertex
struct VkMultiDrawInfoEXT {
uint32_t ;
uint32_t ;
};
Host Memory
...
struct VkMultiDrawInfoEXT {
uint32_t firstVertex ;
uint32_t vertexCount ;
};
void vkCmdDrawMultiEXT(
VkCommandBuffer commandBuffer,
uint32_t drawCount ,
const VkMultiDrawInfoEXT* pVertexInfo ,
uint32_t instanceCount,
uint32_t firstInstance,
uint32_t stride);
drawCount
pVertexInfo

5. void vkCmdDrawIndexed(
VkCommandBuffer commandBuffer,
uint32_t indexCount,
uint32_t instanceCount,
uint32_t firstIndex,
int32_t vertexOffset,
uint32_t firstInstance);
Quick Overview of VK_EXT_multi_draw
Ricardo Garcia, XDC 2021
void vkCmdDrawMultiIndexedEXT(
VkCommandBuffer commandBuffer,
uint32_t drawCount,
const VkMultiDrawIndexedInfoEXT* pIndexInfo,
uint32_t instanceCount,
uint32_t firstInstance,
uint32_t stride,
const int32_t* pVertexOffset);
struct VkMultiDrawIndexedInfoEXT {
uint32_t firstIndex;
uint32_t indexCount;
int32_t vertexOffset;
};
...
struct VkMultiDrawIndexedInfoEXT {
uint32_t firstIndex;
uint32_t indexCount;
int32_t vertexOffset;
};
Host memory

6. Quick Overview of VK_EXT_multi_draw
Ricardo Garcia, XDC 2021
Shout-out to...
 Mike Blumenkrantz (Valve)
●
Authored the extension and created implementations for ANV and RADV.
 Jason Ekstrand (Intel)
●
Reviewed initial version of the extension spec.
 Piers Daniell (NVIDIA)
●
Extension spec review and implementation.

7. Quick Overview of VK_EXT_multi_draw
Ricardo Garcia, XDC 2021
Thanks for watching!