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## Problems with camera looking up

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### #1Telanor  Members

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Posted 09 March 2013 - 10:49 PM

I'm trying to calculate a view/projection/bounding frustum for the 6 directions of a point light and I'm having trouble with the views pointing along the Y axis. Our game uses a right-handed, Y-up system. For the other 4 directions I create the LookAt matrix using (0, 1, 0) as the up vector. Obviously that doesn't work when looking along the Y axis so for those I use an up vector of (-1, 0, 0) for -Y and (1, 0, 0) for +Y. The view matrix seems to come out correctly (and the projection matrix always stays the same), but the bounding frustum is definitely wrong.

This is the code I'm using:
camera.Projection = Matrix.PerspectiveFovRH((float)Math.PI / 2, ShadowMapSize / (float)ShadowMapSize, 1, 5);

for(var i = 0; i < 6; i++)
{
var up = DetermineLightUp((TextureCubeFace) i);
var forward = DirectionToVector((TextureCubeFace) i);

camera.View = Matrix.LookAtRH(Position, Position + forward, up);
camera.BoundingFrustum = new BoundingFrustum(camera.View * camera.Projection);
}

private static Vector3 DirectionToVector(TextureCubeFace direction)
{
switch (direction)
{
case TextureCubeFace.NegativeX:
return -Vector3.UnitX;
case TextureCubeFace.NegativeY:
return -Vector3.UnitY;
case TextureCubeFace.NegativeZ:
return -Vector3.UnitZ;
case TextureCubeFace.PositiveX:
return Vector3.UnitX;
case TextureCubeFace.PositiveY:
return Vector3.UnitY;
case TextureCubeFace.PositiveZ:
return Vector3.UnitZ;
default:
throw new ArgumentOutOfRangeException("direction");
}
}

private static Vector3 DetermineLightUp(TextureCubeFace direction)
{
switch (direction)
{
case TextureCubeFace.NegativeY:
return -Vector3.UnitX;
case TextureCubeFace.PositiveY:
return Vector3.UnitX;
default:
return Vector3.UnitY;
}
}

I can post some example output if it'll help.

Edited by Telanor, 09 March 2013 - 10:51 PM.

### #2riuthamus  Moderators

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Posted 17 March 2013 - 03:51 AM

If this is too technical let us know. I can provide you with a more basic understanding. Curious if anybody had any thoughts on this as it would help us deal with our point light issue. I can provide pictures/video!

Edited by riuthamus, 17 March 2013 - 03:51 AM.

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