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#ActualTengato

Posted 24 July 2013 - 09:55 PM

After a lot of trial and error I was able to get it to work.  Since my light frustum dimensions are fixed, I convert the center point into texel space, floor the X and Y coordinates, then convert it back to world space:

// (sceneBounds.Center has been placed based on the camera frustum.)
sceneBounds.Radius = 50.0f;

float texelsPerWorldUnit = (float)SMAP_SIZE / (sceneBounds.Radius * 2.0f);

Matrix lightViewAtOrigin = Matrix.CreateScale(texelsPerWorldUnit) *
    Matrix.CreateLookAt(Vector3.Zero, -sceneLights[0].Direction, Vector3.Up);

Matrix lightViewAtOriginInv = Matrix.Invert(lightViewAtOrigin);

sceneBounds.Center = Vector3.Transform(sceneBounds.Center, lightViewAtOrigin);
sceneBounds.Center.X = (float)(Math.Floor(sceneBounds.Center.X));
sceneBounds.Center.Y = (float)(Math.Floor(sceneBounds.Center.Y));
sceneBounds.Center = Vector3.Transform(sceneBounds.Center, lightViewAtOriginInv);

lightView = Matrix.CreateLookAt(sceneBounds.Center - sceneLights[0].Direction * 
    sceneBounds.Radius * 2.0f, sceneBounds.Center, Vector3.Up);
lightFrustum = Matrix.CreateOrthographic(sceneBounds.Radius * 2.0f,
    sceneBounds.Radius * 2.0f, 0.0f, sceneBounds.Radius * 6.0f);




#1Tengato

Posted 24 July 2013 - 09:55 PM

After a lot of trial an error I was able to get it to work.  Since my light frustum dimensions are fixed, I convert the center point into texel space, floor the X and Y coordinates, then convert it back to world space:

 

// (sceneBounds.Center has been placed based on the camera frustum.)
sceneBounds.Radius = 50.0f;

float texelsPerWorldUnit = (float)SMAP_SIZE / (sceneBounds.Radius * 2.0f);

Matrix lightViewAtOrigin = Matrix.CreateScale(texelsPerWorldUnit) *
    Matrix.CreateLookAt(Vector3.Zero, -sceneLights[0].Direction, Vector3.Up);

Matrix lightViewAtOriginInv = Matrix.Invert(lightViewAtOrigin);

sceneBounds.Center = Vector3.Transform(sceneBounds.Center, lightViewAtOrigin);
sceneBounds.Center.X = (float)(Math.Floor(sceneBounds.Center.X));
sceneBounds.Center.Y = (float)(Math.Floor(sceneBounds.Center.Y));
sceneBounds.Center = Vector3.Transform(sceneBounds.Center, lightViewAtOriginInv);

lightView = Matrix.CreateLookAt(sceneBounds.Center - sceneLights[0].Direction * 
    sceneBounds.Radius * 2.0f, sceneBounds.Center, Vector3.Up);
lightFrustum = Matrix.CreateOrthographic(sceneBounds.Radius * 2.0f,
    sceneBounds.Radius * 2.0f, 0.0f, sceneBounds.Radius * 6.0f);




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