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    • By fs1
      I have been trying to see how the ID3DInclude, and how its methods Open and Close work.
      I would like to add a custom path for the D3DCompile function to search for some of my includes.
      I have not found any working example. Could someone point me on how to implement these functions? I would like D3DCompile to look at a custom C:\Folder path for some of the include files.
    • By stale
      I'm continuing to learn more about terrain rendering, and so far I've managed to load in a heightmap and render it as a tessellated wireframe (following Frank Luna's DX11 book). However, I'm getting some really weird behavior where a large section of the wireframe is being rendered with a yellow color, even though my pixel shader is hard coded to output white. 

      The parts of the mesh that are discolored changes as well, as pictured below (mesh is being clipped by far plane).

      Here is my pixel shader. As mentioned, I simply hard code it to output white:
      float PS(DOUT pin) : SV_Target { return float4(1.0f, 1.0f, 1.0f, 1.0f); } I'm completely lost on what could be causing this, so any help in the right direction would be greatly appreciated. If I can help by providing more information please let me know.
    • By evelyn4you
      i try to implement voxel cone tracing in my game engine.
      I have read many publications about this, but some crucial portions are still not clear to me.
      At first step i try to emplement the easiest "poor mans" method
      a.  my test scene "Sponza Atrium" is voxelized completetly in a static voxel grid 128^3 ( structured buffer contains albedo)
      b. i dont care about "conservative rasterization" and dont use any sparse voxel access structure
      c. every voxel does have the same color for every side ( top, bottom, front .. )
      d.  one directional light injects light to the voxels ( another stuctured buffer )
      I will try to say what i think is correct ( please correct me )
      GI lighting a given vertecie  in a ideal method
      A.  we would shoot many ( e.g. 1000 ) rays in the half hemisphere which is oriented according to the normal of that vertecie
      B.  we would take into account every occluder ( which is very much work load) and sample the color from the hit point.
      C. according to the angle between ray and the vertecie normal we would weigth ( cosin ) the color and sum up all samples and devide by the count of rays
      Voxel GI lighting
      In priciple we want to do the same thing with our voxel structure.
      Even if we would know where the correct hit points of the vertecie are we would have the task to calculate the weighted sum of many voxels.
      Saving time for weighted summing up of colors of each voxel
      To save the time for weighted summing up of colors of each voxel we build bricks or clusters.
      Every 8 neigbour voxels make a "cluster voxel" of level 1, ( this is done recursively for many levels ).
      The color of a side of a "cluster voxel" is the average of the colors of the four containing voxels sides with the same orientation.

      After having done this we can sample the far away parts just by sampling the coresponding "cluster voxel with the coresponding level" and get the summed up color.
      Actually this process is done be mip mapping a texture that contains the colors of the voxels which places the color of the neighbouring voxels also near by in the texture.
      Cone tracing, howto ??
      Here my understanding is confus ?? How is the voxel structure efficiently traced.
      I simply cannot understand how the occlusion problem is fastly solved so that we know which single voxel or "cluster voxel" of which level we have to sample.
      Supposed,  i am in a dark room that is filled with many boxes of different kind of sizes an i have a pocket lamp e.g. with a pyramid formed light cone
      - i would see some single voxels near or far
      - i would also see many different kind of boxes "clustered voxels" of different sizes which are partly occluded
      How do i make a weighted sum of this ligting area ??
      e.g. if i want to sample a "clustered voxel level 4" i have to take into account how much per cent of the area of this "clustered voxel" is occluded.
      Please be patient with me, i really try to understand but maybe i need some more explanation than others
      best regards evelyn
    • By Endemoniada

      Hi guys, when I do picking followed by ray-plane intersection the results are all wrong. I am pretty sure my ray-plane intersection is correct so I'll just show the picking part. Please take a look:
      // get projection_matrix DirectX::XMFLOAT4X4 mat; DirectX::XMStoreFloat4x4(&mat, projection_matrix); float2 v; v.x = (((2.0f * (float)mouse_x) / (float)screen_width) - 1.0f) / mat._11; v.y = -(((2.0f * (float)mouse_y) / (float)screen_height) - 1.0f) / mat._22; // get inverse of view_matrix DirectX::XMMATRIX inv_view = DirectX::XMMatrixInverse(nullptr, view_matrix); DirectX::XMStoreFloat4x4(&mat, inv_view); // create ray origin (camera position) float3 ray_origin; ray_origin.x = mat._41; ray_origin.y = mat._42; ray_origin.z = mat._43; // create ray direction float3 ray_dir; ray_dir.x = v.x * mat._11 + v.y * mat._21 + mat._31; ray_dir.y = v.x * mat._12 + v.y * mat._22 + mat._32; ray_dir.z = v.x * mat._13 + v.y * mat._23 + mat._33;  
      That should give me a ray origin and direction in world space but when I do the ray-plane intersection the results are all wrong.
      If I click on the bottom half of the screen ray_dir.z becomes negative (more so as I click lower). I don't understand how that can be, shouldn't it always be pointing down the z-axis ?
      I had this working in the past but I can't find my old code
      Please help. Thank you.
    • By turanszkij
      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.
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DX11 Why are we still using index/vertex/instance buffers?

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There are a number of options now in each API for storing data on the GPU. Specifically in DX11, we have Buffers which can be bound as vertex buffers, index buffers, constant buffers or shader resources (structured buffer for example). Constant buffers have the most limitations and I think that's because they are so optimized for non random Access (an optimization of which we have no control of). Vertex buffers and index buffers however have not many limitations compared to shader resource buffers to the point that I question their value.

For example, the common way of drawing geometry is to provide a vertex buffer (and maybe an instance buffer) by a specific call to SetVertexBuffers. We also provide index buffers with a specific call. At this point we also have to provide an input layout. That is significantly more of a management overhead than it would be if we provided the vertex and index buffers through shader resources and indexed them with sysvalues (eg. SV_VertexID) in the shader.

Now, I haven't actually tried doing vertex buffer management this way but I actually looking forward to it if no one points out the faults in my way of thinking.

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Thank you! I actually didn't think of using a dedicated index buffer but I see now that it still has value. What I am also interested in is that this way you can easily do hard edge normals and UV discontinuities without duplicated position vertices. I am already using deinterleaved vertex buffers (for more efficient shadow rendering/zprepass) so implementing that should not be very hard.

Oh and something to keep in mind: graphics debuggers (at least Nsight) cannot visualize geometry information without an input layout, that is certainly a downside of it.

Edited by turanszkij

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BTW since it wasn't explicitly stated what you do is you use a null vertex buffer, this will allow you to generate vertex's procedurally or by fetching them manually using the SV_VertexID and SV_InstanceID system values.  It has been documented here:



Starting page seven.
Edited by Infinisearch

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At the end of the day, vertex buffer and index buffer is just another buffer with semantics attach..as pointed out above I think vertex caching is one of the biggest reason for the having this distinction still as without this, the API will have to be able to flag a generic buffer as being cacheable..

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MJP point 2 is the most important, you need an index buffer in order to benefit from post vertex transform cache, besides that you could, if you only target recent hardware, go SoA (not interleave your vertex data) and fetch manually, that's what will happen on any GCN anyway.

As mentionned by MJP also, nVidia hardware works differently, not sure about latest gen, all consoles being GCN we tend to optimise for it...

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Ugh, I implemented it in my engine for every scene mesh render pass and it performs significantly worse on my GTX 1070 than using regular vertex buffers. I was rendering shadows on the sponza scene in 2ms for 6 point lights and the custom vertex fetch moves it up to 11 ms which is insane). The Z prepass of 0.2 ms got up to 0.4ms. These passes are using position and sometimes texcoord and instance deinterleaved buffers. 

The vertex buffers are float4 buffers which I create as shader resources with DXGI_FORMAT_R32G32B32A32 views. In the shader I declare them as Buffer<float4>. The instance buffers are structured buffers holding 4x4 float matrices.

I don't understand what could be going on but it is very fishy, I expected a very minor performance difference.

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I haven't implemented this myself, but you could try eliminating the overhead of automatic type conversion that buffers have. i.e. the buffer SRV contains a format field, specifying that the data is in a particular format, and the HLSL code says that it wants it converted to DXGI_FORMAT_R32G32B32A32_FLOAT format -- this ability for general purpose conversion might have an overhead on NV?

To avoid that, you could try using a ByteAddressBuffer, and something like asfloat(buffer.Load4(vertexId*16))., which hard-codes the expectation that the buffer will be in DXGI_FORMAT_R32G32B32A32_FLOAT format.

Alternatively you could try using a StructuredBuffer<float4>.

I'd be very interested to know if these three types of buffers have any performance differences... :wink:

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Yeah I will check with the other buffer types too and post my findings. And double check my implementation too, maybe I missed something more obvious. And I am using a hardware index buffer by the way.

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