Sign in to follow this  
Corefanatic

DX11 DX11 deffered render, position saving question

Recommended Posts

Hi all,

I am trying to implement deferred renderer using the description in a book, "Practical Rendering & Computation with Direct3D 11".

The description saves the world space position of the fragments into gbuffer. The problem I have is that the description does not say what DXGI format to use for positions.

Currently I use [font="Arial"][size="2"]DXGI_FORMAT_R8G8B8A8_UNORM for albdeo and specular, and DXGI_FORMAT_R8G8B8A8_SNORM for[/size][/font]
[font="Arial"][size="2"]normalized world space normals[/size][/font]
[font="Arial"][size="2"]
[/size][/font]
[font="Arial"][size="2"]If I use SNORM for position, it will get clamped to -1,1 and this is exactly waht I don'd want.[/size][/font]
[font="Arial"][size="2"]
[/size][/font]
[font="Arial"][size="2"]What should I use in order to save my position?[/size][/font]
[font="Arial"][size="2"]
[/size][/font]
[font="Arial"][size="2"]Thx for any help[/size][/font]

Share this post


Link to post
Share on other sites
DXGI_FORMAT_R32G32B32_FLOAT or 16bit.

edit: there is no 16bit format for 3 components only DXGI_FORMAT_R16G16B16A16_FLOAT.[url=""][/url]


The alternative is that you reconstruct position from z-buffer (google).

Share this post


Link to post
Share on other sites
Hey, I was the author of that chapter.

For the unoptimized version of the deferred renderer, I used a DXGI_FORMAT_R32G32B32A32_FLOAT texture for storing position. Obviously that's inefficient, but the whole point of that section was to do things the simplest way possible without regards for performance. You could also use DXGI_FORMAT_R16G16B16A16_FLOAT for position, but you are likely to encounter precision issues. The best way to do it is to reconstruct position from your depth buffer, which is described in detail in the optimizations section. But I would recommend getting it working with a position buffer first, and worry about optimizing it later.

BTW there's a sample that demonstrates the techniques in that chapter available on the [url="http://hieroglyph3.codeplex.com/"]Hieroglyph 3 site[/url], if you ever need a reference.

Share this post


Link to post
Share on other sites
Thx guys,

MJP I love the book, it is very well written and the diagrams really help since I am a more of a visual learner. Right now I am not too worried about performance until I get everything working.

I will take a look at Hieroglyph.

Btw I am using DX10 feature level, so I cannot have read-only depth buffer, does it mean I have to copy the buffer to read it even if I am using DX11 as API?

Share this post


Link to post
Share on other sites
[quote name='Corefanatic' timestamp='1317415177' post='4867717']
Thx guys,

MJP I love the book, it is very well written and the diagrams really help since I am a more of a visual learner. Right now I am not too worried about performance until I get everything working.
[/quote]

I'm glad you find it useful! If you ever have any questions you can feel free to PM me or ask here. I can also put you in touch with the other 2 authors if necessary.


[quote name='Corefanatic' timestamp='1317415177' post='4867717']
Btw I am using DX10 feature level, so I cannot have read-only depth buffer, does it mean I have to copy the buffer to read it even if I am using DX11 as API?
[/quote]

Yeah unfortunately you can't read from the buffer and use it for depth testing at the same time, so you would need to copy it. Another option is to write out depth to another render target, and use that instead.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Announcements

  • Forum Statistics

    • Total Topics
      628320
    • Total Posts
      2982072
  • Similar Content

    • By GalacticCrew
      In some situations, my game starts to "lag" on older computers. I wanted to search for bottlenecks and optimize my game by searching for flaws in the shaders and the layer between CPU and GPU. My first step was to measure the time my render function needs to solve its tasks. Every second I wrote the accumulated times of each task into my console window. Each second it takes around
      170ms to call render functions for all models (including settings shader resources, updating constant buffers, drawing all indexed and non-indexed vertices, etc.) 40ms to render the UI 790ms to call SwapChain.Present <1ms to do the rest (updating structures, etc.) In my Swap Chain description I set a frame rate of 60 Hz, if its supported by the computer. It made sense for me that the Present function waits some time until it starts the next frame. However, I wanted to check, if this might be a problem for me. After a web search I found articles like this one, which states 
      My drivers are up-to-date so that's no issue. I installed Microsoft's PIX, but I was unable to use it. I could configure my game for x64, but PIX is not able to process DirectX 11.. After getting only error messages, I installed NVIDIA's NSight. After adjusting my game and installing all components, I couldn't get a proper result, but my game freezes after a new frames. I haven't figured out why. There is no exception, error message and other debug mechanisms like log messages and break points tell me the game freezes at the end of the render function after a few frames. So, I looked for another profiling tool and found Jeremy's GPUProfiler. However, the information returned by this tool are too basic to get an in-depth knowledge about my performance issues.
      Can anyone recommend a GPU Profiler or any other tool that might help me to find bottlenecks in my game and or that is able to indicate performance problems in my shaders? My custom graphics engine can handle subjects like multi-texturing, instancing, soft shadowing, animation, etc. However, I am pretty sure, there are things I can optimize!
      I am using SharpDX to develop a game (engine) based on DirectX 11 with .NET Framework 4.5. My graphics cards is from NVIDIA and my processor is made by Intel.
    • By GreenGodDiary
      SOLVED: I had written 
      Dispatch(32, 24, 0) instead of
      Dispatch(32, 24, 1)  
       
      I'm attempting to implement some basic post-processing in my "engine" and the HLSL part of the Compute Shader and such I think I've understood, however I'm at a loss at how to actually get/use it's output for rendering to the screen.
      Assume I'm doing something to a UAV in my CS:
      RWTexture2D<float4> InputOutputMap : register(u0); I want that texture to essentially "be" the backbuffer.
       
      I'm pretty certain I'm doing something wrong when I create the views (what I think I'm doing is having the backbuffer be bound as render target aswell as UAV and then using it in my CS):
       
      DXGI_SWAP_CHAIN_DESC scd; ZeroMemory(&scd, sizeof(DXGI_SWAP_CHAIN_DESC)); scd.BufferCount = 1; scd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM; scd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT | DXGI_USAGE_SHADER_INPUT | DXGI_USAGE_UNORDERED_ACCESS; scd.OutputWindow = wndHandle; scd.SampleDesc.Count = 1; scd.Windowed = TRUE; HRESULT hr = D3D11CreateDeviceAndSwapChain(NULL, D3D_DRIVER_TYPE_HARDWARE, NULL, NULL, NULL, NULL, D3D11_SDK_VERSION, &scd, &gSwapChain, &gDevice, NULL, &gDeviceContext); // get the address of the back buffer ID3D11Texture2D* pBackBuffer = nullptr; gSwapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&pBackBuffer); // use the back buffer address to create the render target gDevice->CreateRenderTargetView(pBackBuffer, NULL, &gBackbufferRTV); // set the render target as the back buffer CreateDepthStencilBuffer(); gDeviceContext->OMSetRenderTargets(1, &gBackbufferRTV, depthStencilView); //UAV for compute shader D3D11_UNORDERED_ACCESS_VIEW_DESC uavd; ZeroMemory(&uavd, sizeof(uavd)); uavd.Format = DXGI_FORMAT_R8G8B8A8_UNORM; uavd.ViewDimension = D3D11_UAV_DIMENSION_TEXTURE2D; uavd.Texture2D.MipSlice = 1; gDevice->CreateUnorderedAccessView(pBackBuffer, &uavd, &gUAV); pBackBuffer->Release();  
      After I render the scene, I dispatch like this:
      gDeviceContext->OMSetRenderTargets(0, NULL, NULL); m_vShaders["cs1"]->Bind(); gDeviceContext->CSSetUnorderedAccessViews(0, 1, &gUAV, 0); gDeviceContext->Dispatch(32, 24, 0); //hard coded ID3D11UnorderedAccessView* nullview = { nullptr }; gDeviceContext->CSSetUnorderedAccessViews(0, 1, &nullview, 0); gDeviceContext->OMSetRenderTargets(1, &gBackbufferRTV, depthStencilView); gSwapChain->Present(0, 0); Worth noting is the scene is rendered as usual, but I dont get any results from the CS (simple gaussian blur)
      I'm sure it's something fairly basic I'm doing wrong, perhaps my understanding of render targets / views / what have you is just completely wrong and my approach just makes no sense.

      If someone with more experience could point me in the right direction I would really appreciate it!

      On a side note, I'd really like to learn more about this kind of stuff. I can really see the potential of the CS aswell as rendering to textures and using them for whatever in the engine so I would love it if you know some good resources I can read about this!

      Thank you <3
       
      P.S I excluded the .hlsl since I cant imagine that being the issue, but if you think you need it to help me just ask

      P:P:S. As you can see this is my first post however I do have another account, but I can't log in with it because gamedev.net just keeps asking me to accept terms and then logs me out when I do over and over
    • By mister345
      Does buffer number matter in ID3D11DeviceContext::PSSetConstantBuffers()? I added 5 or six constant buffers to my framework, and later realized I had set the buffer number parameter to either 0 or 1 in all of them - but they still all worked! Curious why that is, and should they be set up to correspond to the number of constant buffers?
      Similarly, inside the buffer structs used to pass info into the hlsl shader, I added padding inside the c++ struct to make a struct containing a float3 be 16 bytes, but in the declaration of the same struct inside the hlsl shader file, it was missing the padding value - and it still worked! Do they need to be consistent or not? Thanks.
          struct CameraBufferType
          {
              XMFLOAT3 cameraPosition;
              float padding;
          };
    • By noodleBowl
      I was wondering if anyone could explain the depth buffer and the depth stencil state comparison function to me as I'm a little confused
      So I have set up a depth stencil state where the DepthFunc is set to D3D11_COMPARISON_LESS, but what am I actually comparing here? What is actually written to the buffer, the pixel that should show up in the front?
      I have these 2 quad faces, a Red Face and a Blue Face. The Blue Face is further away from the Viewer with a Z index value of -100.0f. Where the Red Face is close to the Viewer with a Z index value of 0.0f.
      When DepthFunc is set to D3D11_COMPARISON_LESS the Red Face shows up in front of the Blue Face like it should based on the Z index values. BUT if I change the DepthFunc to D3D11_COMPARISON_LESS_EQUAL the Blue Face shows in front of the Red Face. Which does not make sense to me, I would think that when the function is set to D3D11_COMPARISON_LESS_EQUAL the Red Face would still show up in front of the Blue Face as the Z index for the Red Face is still closer to the viewer
      Am I thinking of this comparison function all wrong?
      Vertex data just in case
      //Vertex date that make up the 2 faces Vertex verts[] = { //Red face Vertex(Vector4(0.0f, 0.0f, 0.0f), Color(1.0f, 0.0f, 0.0f)), Vertex(Vector4(100.0f, 100.0f, 0.0f), Color(1.0f, 0.0f, 0.0f)), Vertex(Vector4(100.0f, 0.0f, 0.0f), Color(1.0f, 0.0f, 0.0f)), Vertex(Vector4(0.0f, 0.0f, 0.0f), Color(1.0f, 0.0f, 0.0f)), Vertex(Vector4(0.0f, 100.0f, 0.0f), Color(1.0f, 0.0f, 0.0f)), Vertex(Vector4(100.0f, 100.0f, 0.0f), Color(1.0f, 0.0f, 0.0f)), //Blue face Vertex(Vector4(0.0f, 0.0f, -100.0f), Color(0.0f, 0.0f, 1.0f)), Vertex(Vector4(100.0f, 100.0f, -100.0f), Color(0.0f, 0.0f, 1.0f)), Vertex(Vector4(100.0f, 0.0f, -100.0f), Color(0.0f, 0.0f, 1.0f)), Vertex(Vector4(0.0f, 0.0f, -100.0f), Color(0.0f, 0.0f, 1.0f)), Vertex(Vector4(0.0f, 100.0f, -100.0f), Color(0.0f, 0.0f, 1.0f)), Vertex(Vector4(100.0f, 100.0f, -100.0f), Color(0.0f, 0.0f, 1.0f)), };  
    • By mellinoe
      Hi all,
      First time poster here, although I've been reading posts here for quite a while. This place has been invaluable for learning graphics programming -- thanks for a great resource!
      Right now, I'm working on a graphics abstraction layer for .NET which supports D3D11, Vulkan, and OpenGL at the moment. I have implemented most of my planned features already, and things are working well. Some remaining features that I am planning are Compute Shaders, and some flavor of read-write shader resources. At the moment, my shaders can just get simple read-only access to a uniform (or constant) buffer, a texture, or a sampler. Unfortunately, I'm having a tough time grasping the distinctions between all of the different kinds of read-write resources that are available. In D3D alone, there seem to be 5 or 6 different kinds of resources with similar but different characteristics. On top of that, I get the impression that some of them are more or less "obsoleted" by the newer kinds, and don't have much of a place in modern code. There seem to be a few pivots:
      The data source/destination (buffer or texture) Read-write or read-only Structured or unstructured (?) Ordered vs unordered (?) These are just my observations based on a lot of MSDN and OpenGL doc reading. For my library, I'm not interested in exposing every possibility to the user -- just trying to find a good "middle-ground" that can be represented cleanly across API's which is good enough for common scenarios.
      Can anyone give a sort of "overview" of the different options, and perhaps compare/contrast the concepts between Direct3D, OpenGL, and Vulkan? I'd also be very interested in hearing how other folks have abstracted these concepts in their libraries.
  • Popular Now