VulkanTracer (rayx)¶
The VulkanTracer is a ray tracing module using VULKAN by KHRONOS GROUP to efficiently trace rays with hardware acceleration.
In the current version the Vulkan Engine is a Compute Class that runs as much parallel as possible on the GPU.
Current procedure:
- generate rays
- create input and output buffers
- initialize Vulkan
- run the main loop
- clean up
initVulkan():
- create a Vulkan instance
- set up the debug messenger
- pick the physical device and create a logical device to access it
- create the input and output buffers
- create the descriptors to connect the buffers to the shader
- create a compute pipeline and a command buffer for the shader
mainLoop():
- run the command buffer
- read the data from the output buffer
How the VulkanTracer works¶
Buffer types used:¶
A uniform buffer (VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER) is a descriptor type associated with a buffer resource directly, described in a shader as a structure with various members that load operations can be performed on. More here
A storage buffer (VK_DESCRIPTOR_TYPE_STORAGE_BUFFER) is a descriptor type associated with a buffer resource directly, described in a shader as a structure with various members that load, store, and atomic operations can be performed on.
Buffers:¶
| Buffers | Size ( vkDeviceSize) | Usage | Name |
|---|---|---|---|
| 0 | NumverOfRays*RAY_DOUBLE_AMOUNT | Transfer_DST|STORAGE_BUFFER | Ray Buffer |
| 1 | NumberOfRays*RAY_DOUBLE_AMOUNT | Transfer_SRC|STORAGE_BUFFER | Output Buffer |
| 2 | Quadric_parm+beamlineSize | STORAGE_BUFFER | Quadric Buffer |
| 3 | 100 | STORAGE_BUFFER | Buffer for xyznull |
| 4 | xxxxxxxxxxxxxxx | STORAGE_BUFFER | materialIndexBuf |
| 5 | xxxxxxxxxxxxxxx | STORAGE_BUFFER | materialBuf |
| 6 | xxxxxxxxxxxxxxx | STORAGE_BUFFER | debugBuffer |
| X | min(GPU_MAX_STAGING,numberOfRays) | STORAGE|DST|SRC | Staging Buffer |
Buffer Usages:¶
VK_BUFFER_USAGE_TRANSFER_SRC_BIT specifies that the buffer can be used as the source of a transfer command (see the definition of VK_PIPELINE_STAGE_TRANSFER_BIT).
VK_BUFFER_USAGE_TRANSFER_DST_BIT specifies that the buffer can be used as the destination of a transfer command.