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  • Hash : 3515113e
    Author : Gowtham Tammana
    Date : 2024-06-24T15:10:28

    CL/Vulkan: Remove redundant state in CLImageVk
    
    Much of the image state can be queried from the front-end object.
    Removing all the redundant state from CLImageVk.
    
    Bug: angleproject:378103913
    Change-Id: I7783674da891d1af768375e5d8efd1937c4a4177
    Signed-off-by: Gowtham Tammana <g.tammana@samsung.com>
    Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6004687
    Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
    Reviewed-by: Geoff Lang <geofflang@chromium.org>
    

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    Git SSH git@git.kmx.io:kc3-lang/angle.git
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    Description

    A conformant OpenGL ES implementation for Windows, Mac, Linux, iOS and Android.

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    thodg_m kc3_lang_org thodg_w www_kmx_io thodg thodg_l
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  • README.md

  • ANGLE: Vulkan Back-end

    ANGLE’s Vulkan back-end implementation lives in this folder.

    Vulkan is an explicit graphics API. Compared to APIs like OpenGL or D3D11 explicit APIs can offer a number of significant benefits:

    • Lower API call CPU overhead.
    • A smaller API surface with more direct hardware control.
    • Better support for multi-core programming.
    • Vulkan in particular has open-source tooling and tests.

    Back-end Design

    The vk::Renderer class represents an EGLDisplay. vk::Renderer 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 glDrawArrays and glDrawElements.

    Command recording

    A render pass has three states: unstarted, started and active (we call it active in short), started but inactive (we call it inactive in short). The back-end records commands into command buffers via the following ContextVk APIs:

    • beginNewRenderPass: Writes out (aka flushes) prior pending commands into a primary command buffer, then starts a new render pass. Returns a secondary command buffer inside a render pass instance.
    • getOutsideRenderPassCommandBuffer: May flush prior command buffers and close the render pass if necessary, in addition to issuing the appropriate barriers. Returns a secondary command buffer outside a render pass instance.
    • getStartedRenderPassCommands: Returns a reference to the currently open render pass’ commands buffer.
    • onRenderPassFinished: Puts render pass into inactive state where you can not record more commands into secondary command buffer, except in some special cases where ANGLE does some optimization internally.
    • flushCommandsAndEndRenderPassWithoutSubmit: Marks the end of render pass. It flushes secondary command buffer into vulkan’s primary command buffer, puts secondary command buffer back to unstarted state and then goes into recycler for reuse.

    The back-end (mostly) records Image and Buffer barriers through additional CommandBufferAccess APIs, the result of which is passed to getOutsideRenderPassCommandBuffer. Note that the barriers are not actually recorded until getOutsideRenderPassCommandBuffer is called:

    • onBufferTransferRead and onBufferComputeShaderRead accumulate VkBuffer read barriers.
    • onBufferTransferWrite and onBufferComputeShaderWrite accumulate VkBuffer write barriers.
    • onBuffferSelfCopy is a special case for VkBuffer self copies. It behaves the same as write.
    • onImageTransferRead and onImageComputerShadeRead accumulate VkImage read barriers.
    • onImageTransferWrite and onImageComputerShadeWrite accumulate VkImage write barriers.
    • onImageRenderPassRead and onImageRenderPassWrite accumulate VkImage barriers inside a started RenderPass.

    After the back-end records commands to the primary buffer and we flush (e.g. on swap) or when we call vk::Renderer::finishQueueSerial, ANGLE submits the primary command buffer to a VkQueue.

    See the code for more details.

    Simple command recording example

    In this example we’ll be recording a buffer copy command:

        // Ensure that ANGLE sets proper read and write barriers for the Buffers.
        vk::CommandBufferAccess access;
        access.onBufferTransferWrite(dstBuffer);
        access.onBufferTransferRead(srcBuffer);
    
        // Get a pointer to a secondary command buffer for command recording.
        vk::OutsideRenderPassCommandBuffer *commandBuffer;
        ANGLE_TRY(contextVk->getOutsideRenderPassCommandBuffer(access, &commandBuffer));
    
        // Record the copy command into the secondary buffer. We're done!
        commandBuffer->copyBuffer(srcBuffer->getBuffer(), dstBuffer->getBuffer(), copyCount, copies);

    Additional Reading

    More implementation details can be found in the doc directory: