ANGLE's Vulkan back-end implementation lives in this folder.
Vulkan is an explicit graphics API. It has a lot in common with other explicit APIs such as Microsoft‘s D3D12 and Apple’s Metal. Compared to APIs like OpenGL or D3D11 explicit APIs can offer a number of significant benefits:
RendererVk class represents an
RendererVk owns shared global resources like the VkDevice, VkQueue, the Vulkan format tables and internal Vulkan shaders. The ContextVk class implements the back-end of a front-end OpenGL Context. ContextVk processes state changes and handles action commands like
The back-end records commands into command buffers via the the following
endRenderPassAndGetCommandBuffer: returns a secondary command buffer outside a RenderPass instance.
flushAndBeginRenderPass: returns a secondary command buffer inside a RenderPass instance.
flushAndGetPrimaryCommandBuffer: returns the primary command buffer. You should rarely need this API.
Note: All of these commands may write out (aka flush) prior pending commands into a primary command buffer. When a RenderPass is open
endRenderPassAndGetCommandBuffer will flush the pending RenderPass commands.
flushAndBeginRenderPass will flush out pending commands outside a RenderPass to a primary buffer. On submit ANGLE submits the primary command buffer to a
If you need to record inside a RenderPass, use
flushAndBeginRenderPass. Otherwise, use
endRenderPassAndGetCommandBuffer. You should rarely need to call
flushAndGetPrimaryCommandBuffer. It's there for commands like debug labels, barriers and queries that need to be recorded serially on the primary command buffer.
The back-end usually records Image and Buffer barriers through additional
onRenderPassImageWriteis a special API for write barriers inside a RenderPass instance.
After the back-end records commands to the primary buffer we flush (e.g. on swap) or when we call
See the code for more details.
In this example we'll be recording a buffer copy command:
# Ensure that ANGLE sets proper read and write barriers for the Buffers. ANGLE_TRY(contextVk->onBufferTransferWrite(destBuffer)); ANGLE_TRY(contextVk->onBufferTransferRead(srcBuffer)); # Get a pointer to a secondary command buffer for command recording. May "flush" the RP. vk::CommandBuffer *commandBuffer; ANGLE_TRY(contextVk->endRenderPassAndGetCommandBuffer(&commandBuffer)); # Record the copy command into the secondary buffer. We're done! commandBuffer->copyBuffer(srcBuffer->getBuffer(), destBuffer->getBuffer(), copyCount, copies);
More implementation details can be found in the