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| Quaternion Water Reflection |
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ultimastrike Member since: 1/17/2008 From: Frederick, MD, United States |
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 Posted - 3/7/2009 2:38:47 PM |
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| Hello all. I have made a lot of progress from my last post here, but I have encountered another snag. I've been following Reimer's tutorial on terrain, and am trying to create water reflections. I've done his jpg output debugging and my Refraction map looks perfectly correct. My problem is with the reflection map. The difference between my code and his is that I'm storing my camera's orientation in a quaternion whereas he has a simpler implementation, so I am having difficulty figuring out how to get the reflection camera. I understand that I need Camera B's position, target and up vector. This is the code I have to figure them out based on the camera's Orentation quaternion. Note that Camera A is an orbit camera, so its target is always player1.Position.
Matrix cameraRotation = Matrix.CreateFromQuaternion(camera.Orientation);
Vector3 cameraFinalTarget = Player1.Position;
Vector3 reflCameraPosition = camera.Position;
reflCameraPosition.Y = -camera.Position.Y + waterHeight * 2;
Vector3 reflTargetPos = cameraFinalTarget;
reflTargetPos.Y = -cameraFinalTarget.Y + waterHeight * 2;
Vector3 cameraRight = Vector3.Transform(new Vector3(1, 0, 0), cameraRotation);
Vector3 invUpVector = Vector3.Cross(cameraRight, reflTargetPos - reflCameraPosition);
reflectionViewMatrix = Matrix.CreateLookAt(reflCameraPosition, reflTargetPos, invUpVector);
I have tried to model the code Reimer uses in his UpdateViewMatrix function, but I can't seem to get it to work right for quaternions. I get endlessly repeating patterns of little sky ovals stretching away into the distance between huge black bands. Is this enough information, or should I post a screenshot? |
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ultimastrike Member since: 1/17/2008 From: Frederick, MD, United States |
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Posted - 3/7/2009 4:57:18 PM |
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| I guess this is a pretty specific subject, heh. Not a lot of people must know how to do this, or it must be so dumb that no one ever does do it. |
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jyk GDNet+ Member since: 10/23/2003 |
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 Posted - 3/7/2009 5:06:17 PM |
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I don't know enough about the context to say for sure what's wrong, but this line looks a little suspicious:Vector3 invUpVector = Vector3.Cross(cameraRight, reflTargetPos - reflCameraPosition);Unless there are constraints in place that aren't evident from what you posted, invUpVector won't necessarily be unit length, in which case the view matrix will most likely be incorrect. [ Configurable Math Library ] |
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ultimastrike Member since: 1/17/2008 From: Frederick, MD, United States |
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Posted - 3/7/2009 5:09:41 PM |
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| Currently I am using this code, which is much simpler but seems to yield the same results: Vector3 reflectPos = camera.Position; Vector3 reflectForward = camera.ViewDirection; reflectForward.Z = waterHeight - (reflectForward.Z - waterHeight); reflectionViewMatrix = Matrix.CreateLookAt(reflectPos, reflectPos + reflectForward, new Vector3(0,0,1)); This is an image of the results: Failed Reflection These are screencaps of the Reflection map and the Refraction map. As you can see, the refraction map is correct but the reflection map is bonkers. Reflection Map Refraction Map |
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ultimastrike Member since: 1/17/2008 From: Frederick, MD, United States |
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Posted - 3/7/2009 9:45:37 PM |
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| I'm a lot closer, but it still isn't right. I get sky and land reflections, but they seem to be upside down! This is what I'm working with now. Vector3 reflectPos = camera.Position; Vector3 reflectForward = camera.ViewMatrix.Forward; reflectPos.Y = -reflectPos.Y + 2 * waterHeight; reflectForward.Y = -reflectForward.Y + 2 * waterHeight; reflectionViewMatrix = Matrix.CreateLookAt(reflectPos, reflectPos + reflectForward, camera.ViewMatrix.Up); |
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