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    • 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
      Hello,
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      I have read many publications about this, but some crucial portions are still not clear to me.
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      Voxel GI lighting
      In priciple we want to do the same thing with our voxel structure.
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      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.
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    • 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.
    • By evelyn4you
      Hello,
      in my game engine i want to implement my own bone weight painting tool, so to say a virtual brush painting tool for a mesh.
      I have already implemented my own "dual quaternion skinning" animation system with "morphs" (=blend shapes)  and "bone driven"  "corrective morphs" (= morph is dependent from a bending or twisting bone)
      But now i have no idea which is the best method to implement a brush painting system.
      Just some proposals
      a.  i would build a kind of additional "vertecie structure", that can help me to find the surrounding (neighbours) vertecie indexes from a given "central vertecie" index
      b.  the structure should also give information about the distance from the neighbour vertecsies to the given "central vertecie" index
      c.  calculate the strength of the adding color to the "central vertecie" an the neighbour vertecies by a formula with linear or quadratic distance fall off
      d.  the central vertecie would be detected as that vertecie that is hit by a orthogonal projection from my cursor (=brush) in world space an the mesh
            but my problem is that there could be several  vertecies that can be hit simultaniously. e.g. i want to paint the inward side of the left leg. the right leg will also be hit.
      I think the given problem is quite typical an there are standard approaches that i dont know.
      Any help or tutorial are welcome
      P.S. I am working with SharpDX, DirectX11
        
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DX11 Why is this 1?

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7rqrAH5.png

Image Source: Frank D. Luna's DX11 book.

 

BTW, can anyone please explain me directx projection matrix and how it's derived.

Edited by newtechnology

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I'm horrible at math so we can hope that someone that knows more soon answers cool.png . I think that the 1 i related to that the DirectX clipping volume ranges from -1.0 to 1.0. So whatever you set the other values to it needs to work with the 1 there.

 

https://msdn.microsoft.com/en-us/library/windows/desktop/bb206341%28v=vs.85%29.aspx . Search for clipping volume.

 

Ohh that was DX9 i see know. Might be changed with 11.

Edited by Spinningcubes

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Like Olaf says, its convention and has nice properties WRT how floating point works (namely, there is as much precision betwen 0 and 1 as there is between 1 and the largest number the floating point format can represent).

 

Those are the normalized device coordinates (NDC).

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Yes, 2 units from top to bottom and from left to right, by convention ranging from -1 to +1 in both axis (again, what I said about precision between 0 and 1 above is also true for 0 to -1. In floating point, the numbers between -1 and +1 encompass exactly half of all the values the format can represent.)

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by convention ranging from -1 to +1 in both axis

 

That's correct with regard to range.

 

Just to be clear, the ( x, y ) screen coordinates that result are ( -1, +1 ) at the upper-left to ( +1, -1 ) at the lower-right. That represents a Cartesian system with the origin at center-screen, with -X to the left, +Y up, +X to the right, and -Y down.

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It's called screen space and is the final result of your transformations.

 

The vertices of your objects are transformed from object-local space to world space through the world matrix, so the model is correctly positioned and rotated in the game world.

Then they are transformed again by the View Matrix into view space which means they are now correctly position relative to the camera.

 

All these spaces so far are in standard 3d cartesian coordinates ranging from 0 to INF on all 3 axis.

 

Now as final step through the Projection Matrix the object is transformed into projection space which is a normalized cube with coordinates from -1 to 1 on all sides.

If you flatten this cube to a square you get the Screen Space which is in normalized device coordinates and therefore by definition ranging from -1 to 1 on both X and Y axis.

 

You can for example draw an image to full screen by sending it to the GPU as a quad with XY coordinates 1/1, 1/-1, -1/-1 and -1/1 and applying no transformation.

This is called screen space rendering

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I think it's kind of confusing showing the normalised device coordinates on the same diagram as the view frustum.

 

It seems like a somewhat separate concept to me, and there's no reason that projection window line couldn't sit to the right of the near plane, or even to the right of the far plane!

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