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    • By evelyn4you
      Hello,
      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
      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
        
    • By Luca Davidian
      Hi, I'm implementing a simple 3D engine based on DirectX11. I'm trying to render a skybox with a cubemap on it and to do so I'm using DDS Texture Loader from DirectXTex library. I use texassemble to generate the cubemap (texture array of 6 textures) into a DDS file that I load at runtime. I generated a cube "dome" and sample the texture using the position vector of the vertex as the sample coordinates (so far so good), but I always get the same face of the cubemap mapped on the sky. As I look around I always get the same face (and it wobbles a bit if I move the camera). My code:   
      //Texture.cpp:         Texture::Texture(const wchar_t *textureFilePath, const std::string &textureType) : mType(textureType)         {             //CreateDDSTextureFromFile(Game::GetInstance()->GetDevice(), Game::GetInstance()->GetDeviceContext(), textureFilePath, &mResource, &mShaderResourceView);             CreateDDSTextureFromFileEx(Game::GetInstance()->GetDevice(), Game::GetInstance()->GetDeviceContext(), textureFilePath, 0, D3D11_USAGE_DEFAULT, D3D11_BIND_SHADER_RESOURCE, 0, D3D11_RESOURCE_MISC_TEXTURECUBE, false, &mResource, &mShaderResourceView);         }     // SkyBox.cpp:          void SkyBox::Draw()     {         // set cube map         ID3D11ShaderResourceView *resource = mTexture.GetResource();         Game::GetInstance()->GetDeviceContext()->PSSetShaderResources(0, 1, &resource);              // set primitive topology         Game::GetInstance()->GetDeviceContext()->IASetPrimitiveTopology(D3D_PRIMITIVE_TOPOLOGY_TRIANGLELIST);              mMesh.Bind();         mMesh.Draw();     }     // Vertex Shader:     cbuffer Transform : register(b0)     {         float4x4 viewProjectionMatrix;     };          float4 main(inout float3 pos : POSITION) : SV_POSITION     {         return mul(float4(pos, 1.0f), viewProjectionMatrix);     }     // Pixel Shader:     SamplerState cubeSampler;     TextureCube cubeMap;          float4 main(in float3 pos : POSITION) : SV_TARGET     {         float4 color = cubeMap.Sample(cubeSampler, pos.xyz);         return color;     } I tried both functions grom DDS loader but I keep getting the same result. All results I found on the web are about the old SDK toolkits, but I'm using the new DirectXTex lib.
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DX11 draw lights in render engine

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I 'm going to write the lighting  for game.  I have read many code,  and finally conclude two way to draw light models.

 

1) 

 foreach(model in models) 

  model.draw(model.material,  model.HitLights);    // the hit lights are pick up by collision test.

  // if no hit lights, it will be drawed  with ambient.

}

 

To implement this method , it seems to precompile many technique,  material + 1 light, material + 2 lights ....

 

 

 

2)  

   the so called forward lighting ????

  drawall(models, ambient light);

  foreach(light in lightlist)   

  {

      find hit models;

      bindpass(lightingpass);

      foreach(model  in   hits) 

          draw(model, light);

  }

 

this method look more simple,  because I only need to write one shader file. 

 

If not considering efficiency, the second one  may look better.   For the moment, I don't want to use deferred lighting technique.

 

How do you do forward lighting ? 

 

In the second method, how to real time combine other shader into the main lighting shader ?

For instance, the main lighting shader code in the file lighting.shader.  And   a shader file  aa.shader    which has a  function  computeColor().

How to real time combine the code from aa.shader  into  the lightin.shader.

so the main() in lighting.shader can call the computeColor() ?   

hehe,  i'm now using dx11

Edited by poigwym

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Those are both different implementations of forward lighting. (1) Is single pass forward lighting and (2) is multi-pass forward lighting.
(2) Used to be popular back before shaders, or with the early shader models.
(1) Replaced it when shaders became flexibly enough.

They should both produce the same visual result -- except if you're not doing HDR (e.g. are using an 8-bit back buffer). In that situation, (2) will have an implicit saturate(result) at the end of every light, whereas (1) will only have this implicit clamp right at the end of the lighting loop.
 
There's also a middle-ground that prevents a technique explosion -- stop at material + N lights, and use
foreach(model in models) 
{ 
  for( i = 0; i < model.HitLights; i += N )
    model.draw(model.material,  model.HitLights.SubRange(i, i+N) );
}
Or another alternative -- you used to pre-compile many shader permutations (material + 1 light, material + 2 lights ...) because using a dynamic loop inside a shader used to be extremely slow.
These days, loops are pretty damn cheap though, so you can just put the number of a lights (and an array of light data) into a cbuffer and use a single shader technique for any number of lights in one pass. Edited by Hodgman

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They should both produce the same visual result -- except if you're not doing HDR (e.g. are using an 8-bit back buffer). In that situation, (2) will have an implicit saturate(result) at the end of every light, whereas (1) will only have this implicit clamp right at the end of the lighting loop. 

 

Can you explain it ?

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What you're not mentioning is how (if at all) you're planning to implement shadows.  Method 2 will integrate more cleanly with typical shadowing techniques, especially if you want to have an arbitrary number of shadow-casting lights.

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