• Advertisement
  • Popular Tags

  • Popular Now

  • Advertisement
  • Similar Content

    • By turanszkij
      Hi, I am having problems with all of my compute shaders in Vulkan. They are not writing to resources, even though there are no problems in the debug layer, every descriptor seem correctly bound in the graphics debugger, and the shaders definitely take time to execute. I understand that this is probably a bug in my implementation which is a bit complex, trying to emulate a DX11 style rendering API, but maybe I'm missing something trivial in my logic here? Currently I am doing these:
      Set descriptors, such as VK_DESCRIPTOR_TYPE_STORAGE_BUFFER for a read-write structured buffer (which is non formatted buffer) Bind descriptor table / validate correctness by debug layer Dispatch on graphics/compute queue, the same one that is feeding graphics rendering commands.  Insert memory barrier with both stagemasks as VK_PIPELINE_STAGE_ALL_COMMANDS_BIT and srcAccessMask VK_ACCESS_SHADER_WRITE_BIT to dstAccessMask VK_ACCESS_SHADER_READ_BIT Also insert buffer memory barrier just for the storage buffer I wanted to write Both my application behaves like the buffers are empty, and Nsight debugger also shows empty buffers (ssems like everything initialized to 0). Also, I tried the most trivial shader, writing value of 1 to the first element of uint buffer. Am I missing something trivial here? What could be an other way to debug this further?
       
    • By khawk
      LunarG has released new Vulkan SDKs for Windows, Linux, and macOS based on the 1.1.73 header. The new SDK includes:
      New extensions: VK_ANDROID_external_memory_android_hardware_buffer VK_EXT_descriptor_indexing VK_AMD_shader_core_properties VK_NV_shader_subgroup_partitioned Many bug fixes, increased validation coverage and accuracy improvements, and feature additions Developers can download the SDK from LunarXchange at https://vulkan.lunarg.com/sdk/home.

      View full story
    • By khawk
      LunarG has released new Vulkan SDKs for Windows, Linux, and macOS based on the 1.1.73 header. The new SDK includes:
      New extensions: VK_ANDROID_external_memory_android_hardware_buffer VK_EXT_descriptor_indexing VK_AMD_shader_core_properties VK_NV_shader_subgroup_partitioned Many bug fixes, increased validation coverage and accuracy improvements, and feature additions Developers can download the SDK from LunarXchange at https://vulkan.lunarg.com/sdk/home.
    • By mark_braga
      I have a pretty good experience with multi gpu programming in D3D12. Now looking at Vulkan, although there are a few similarities, I cannot wrap my head around a few things due to the extremely sparse documentation (typical Khronos...)
      In D3D12 -> You create a resource on GPU0 that is visible to GPU1 by setting the VisibleNodeMask to (00000011 where last two bits set means its visible to GPU0 and GPU1)
      In Vulkan - I can see there is the VkBindImageMemoryDeviceGroupInfoKHR struct which you add to the pNext chain of VkBindImageMemoryInfoKHR and then call vkBindImageMemory2KHR. You also set the device indices which I assume is the same as the VisibleNodeMask except instead of a mask it is an array of indices. Till now it's fine.
      Let's look at a typical SFR scenario:  Render left eye using GPU0 and right eye using GPU1
      You have two textures. pTextureLeft is exclusive to GPU0 and pTextureRight is created on GPU1 but is visible to GPU0 so it can be sampled from GPU0 when we want to draw it to the swapchain. This is in the D3D12 world. How do I map this in Vulkan? Do I just set the device indices for pTextureRight as { 0, 1 }
      Now comes the command buffer submission part that is even more confusing.
      There is the struct VkDeviceGroupCommandBufferBeginInfoKHR. It accepts a device mask which I understand is similar to creating a command list with a certain NodeMask in D3D12.
      So for GPU1 -> Since I am only rendering to the pTextureRight, I need to set the device mask as 2? (00000010)
      For GPU0 -> Since I only render to pTextureLeft and finally sample pTextureLeft and pTextureRight to render to the swap chain, I need to set the device mask as 1? (00000001)
      The same applies to VkDeviceGroupSubmitInfoKHR?
      Now the fun part is it does not work  . Both command buffers render to the textures correctly. I verified this by reading back the textures and storing as png. The left texture is sampled correctly in the final composite pass. But I get a black in the area where the right texture should appear. Is there something that I am missing in this? Here is a code snippet too
      void Init() { RenderTargetInfo info = {}; info.pDeviceIndices = { 0, 0 }; CreateRenderTarget(&info, &pTextureLeft); // Need to share this on both GPUs info.pDeviceIndices = { 0, 1 }; CreateRenderTarget(&info, &pTextureRight); } void DrawEye(CommandBuffer* pCmd, uint32_t eye) { // Do the draw // Begin with device mask depending on eye pCmd->Open((1 << eye)); // If eye is 0, we need to do some extra work to composite pTextureRight and pTextureLeft if (eye == 0) { DrawTexture(0, 0, width * 0.5, height, pTextureLeft); DrawTexture(width * 0.5, 0, width * 0.5, height, pTextureRight); } // Submit to the correct GPU pQueue->Submit(pCmd, (1 << eye)); } void Draw() { DrawEye(pRightCmd, 1); DrawEye(pLeftCmd, 0); }  
    • By turanszkij
      Hi,
      I finally managed to get the DX11 emulating Vulkan device working but everything is flipped vertically now because Vulkan has a different clipping space. What are the best practices out there to keep these implementation consistent? I tried using a vertically flipped viewport, and while it works on Nvidia 1050, the Vulkan debug layer is throwing error messages that this is not supported in the spec so it might not work on others. There is also the possibility to flip the clip scpace position Y coordinate before writing out with vertex shader, but that requires changing and recompiling every shader. I could also bake it into the camera projection matrices, though I want to avoid that because then I need to track down for the whole engine where I upload matrices... Any chance of an easy extension or something? If not, I will probably go with changing the vertex shaders.
  • Advertisement
  • Advertisement
Sign in to follow this  

Vulkan Vulkan and mipmap generation

This topic is 708 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I'm implementing the Scalable Ambient Obscurance algorithm on Vulkan ; at some point the algorithm is generating a mipchain on a linearized depth texture. I use a render pass to generate a linear depth texture and do the actual SAO computation. Then I use 2 compute shaders for the bilateral filtering since I can use shared memory to lessen memory bandwidth pressure.

I wonder what is the best way to do it in Vulkan ; the mipmap generation step would occur between the depth linear step and the SAO computation one. I can use a compute shader for every mipmap level ; introducing CS between graphic shaders is however not recommended since on some gpu (geforce ?) it triggers a unit reconfiguration and a cache flush. Since there is no advantage in using shared memory here the penalty can't be counterbalanced as for the bilateral passes. I could use a CS for the sao computation algorithm too but I rely on the dFdX function which is only available in fragment shader.

I can use a render pass too however I'm not sure how it will map to hardware. Since mipmap levels have different size it means using as many render passes as there are mipmap level. I fear this scenario may be suboptimal for renderpass and that switching renderpasses may increase an overhead of some sort.

Share this post


Link to post
Share on other sites
Advertisement

On some of my back-ends, I implement mip-map generation using compute - which turned out to be faster than my PS based approach. The CS optimization that I used was to calculate and generate 3 mip levels per dispatch, which greatly reduces the number of passes required to compute the full chain.

i.e. I read 8x8 pixels, output 4x4 to the 1st RWTexture, 2x2 to the 2nd, and 1px to the 3rd.

 

You're right though that this graphics->compute->graphics transition could be quite bad on some GPU's... so maybe I should have two code-paths -- this CS mipping for some GPU's, and a PS fallback for others...

Share this post


Link to post
Share on other sites

I think vkCmdBlitImage is likely to be a superior option for mipmap generation than using a render pass per mipmap level. Not sure how vkCmdBlitImage stacks up against a compute shader though.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement