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    • 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:
       
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      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.
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    • By evelyn4you
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    • 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:   
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    • By B. /
      Hi Guys,
      i want to draw shadows of a direction light but the shadows always disappear, if i translate my mesh (cube) in the world to far of the bounds of my orthographic projection matrix.
      That my code (Based of an XNA sample i recode for my project):
      // Matrix with that will rotate in points the direction of the light Matrix lightRotation = Matrix.LookAtLH(Vector3.Zero, lightDir, Vector3.Up); BoundingFrustum cameraFrustum = new BoundingFrustum(Matrix.Identity); // Get the corners of the frustum Vector3[] frustumCorners = cameraFrustum.GetCorners(); // Transform the positions of the corners into the direction of the light for (int i = 0; i < frustumCorners.Length; i++) frustumCorners[i] = Vector4F.ToVector3(Vector3.Transform(frustumCorners[i], lightRotation)); // Find the smallest box around the points BoundingBox lightBox = BoundingBox.FromPoints(frustumCorners); Vector3 boxSize = lightBox.Maximum - lightBox.Minimum; Vector3 halfBoxSize = boxSize * 0.5f; // The position of the light should be in the center of the back pannel of the box. Vector3 lightPosition = lightBox.Minimum + halfBoxSize; lightPosition.Z = lightBox.Minimum.Z; // We need the position back in world coordinates so we transform // the light position by the inverse of the lights rotation lightPosition = Vector4F.ToVector3(Vector3.Transform(lightPosition, Matrix.Invert(lightRotation))); // Create the view matrix for the light this.view = Matrix.LookAtLH(lightPosition, lightPosition + lightDir, Vector3.Up); // Create the projection matrix for the light // The projection is orthographic since we are using a directional light int amount = 25; this.projection = Matrix.OrthoOffCenterLH(boxSize.X - amount, boxSize.X + amount, boxSize.Y + amount, boxSize.Y - amount, -boxSize.Z - amount, boxSize.Z + amount); I believe the bug is by cameraFrustum to set a Matrix Idetity. I also tried with a Translation Matrix of my Camera Position and also the View Matrix of my Camera, but without success
      Can anyone tell me, how to draw shadows of my direction light always where my camera is current in my scene?
      Greets
      Benjamin
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DX11 [DX11] InterlockedMin works wrong?

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hello,

[size=2]code snippet from Compute Shader 5.0:

groupshared int3 sMin;
...
InterlockedMin(sMin.x, asint(viewPosition.x));
...

In code snippet above there is groupshared variable that holds minimum position value across the thread group. I noticed the case that the InterlockedMin works wrong when sMin.x == 0 and viewPosition == some_negaive_sign_value. After the operation sMin.x == 0.

Question: why negative value doesn't take as minimal value? In documentation mentioned that uint and int types are supported by InterlockedMin, so the sine should takes in account in case of int type.

I use nSight to profiler via network to debug shaders. The graphics adapter on target PC is GeForce GTX 460.

Any help would be appreciated.. Edited by user88

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I found work around simply inverting sign bit. For those who are interested:

groupshared uint3 sMin;
...
uint3 InvertSignBit(uint3 value)
{
return ((~value) &amp;amp; uint3(0x80000000, 0x80000000, 0x80000000)) | (value &amp;amp; uint3(0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF));
}
...
InterlockedMin(sMin.x, InvertSignBit(asint(viewPosition).x);
...
GroupMemoryBarrierWithGroupSync();
uint3 signedSMin = InvertSignBit(sMin);
float3 minViewPosition = asfloat(signedSMin);


Edit:
No.. Unfortunately this is not a solution. Min for values with negative sing is wrong. Edited by user88

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InterlockedMin takes a uint parameter, hence it only works with unsigned integers. If you pass it an int, it will treat it as an unsigned integer which will cause negative numbers to be treated as greater than positive numbers.

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Ok, thanks for answer MJP. Strange why Microsoft didn't noticed it in MSDN?..

For those who are interested in work around, i use two functions for signed values (this time the code is working &lt;_&lt;) :

uint IntToUIntInRange(uint value)
{
if ((value & 0x80000000) == 0)
{
return 0x80000000 | value;
}
else
{
return ~value;
}
}
uint UIntToIntInRange(uint value)
{
if ((value & 0x80000000) != 0)
{
return 0x7FFFFFFF & value;
}
else
{
return ~value;
}
}

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