D3DXMATRIX StartMatrix; //Where the object started
D3DXMATRIX CurrentMatrix; //Where the object is now
D3DXMATRIX TargetMatrix; //Where the object is going
D3DXMATRIX DifferenceMatrix;
long TweenStartTime;
long TweenEndTime;
float PercentComplete; //How far complete is the tween?
PercentComplete = ((float)(TweenEndTime - TweenStartTime)/1000.0f);
DifferenceMatrix = TargetMatrix - StartMatrix;
CurrentMatrix = StartMatrix + (DifferenceMatrix * PercentComplete);
Tweening using Matrices?
Author
Here's my situation:
I have a static object that I want to move from its starting location/orientation to a target location/orientation. I have the matrices representing each, but I want to tween between them over a given time period (1000 milliseconds, for example).
Is it possible to tween location and orientation using matrices? For example, could I do something like this (Semi-Pseudocode)
You can''t intorpolate an orientation/transformation matrix.
What you can do is interpolate a quaternion using slerp.
You can represent your matricies as quaternions.
Hope that helps.
What you can do is interpolate a quaternion using slerp.
You can represent your matricies as quaternions.
Hope that helps.
Author
Could you post an example of what you''re talking about?
You''re saying that if I convert my matrices to quaternions, then I can slerp between them?
You''re saying that if I convert my matrices to quaternions, then I can slerp between them?
O.k, without getting deep into quaternions (there are good docs on this on gamedev, and other sites.)
But a quaternion records an axis and an orientation, so every matrix can be represented by a quaternion.
(A quick check in the docs pulled out this nice function)
D3DXQuaternionRotationMatrix
You transform your 2 rotation matricies to a quaternion. Now you can use D3DXQuaternionSlerp to interpolate between one and the other.
You can then use D3DXMatrixRotationQuaternion to get it back
This is why quaternions are powerful, you can't interpolate between two matricies, but you can convert a matrix to an equivalent quaternion, and interpolate between them.
Some pseudo code would look something like this
Hope this helps. (I just wrote the code out, I never compiled it, but something like this should work for you)
[edited by - ataru on February 6, 2004 6:03:44 PM]
But a quaternion records an axis and an orientation, so every matrix can be represented by a quaternion.
(A quick check in the docs pulled out this nice function)
D3DXQuaternionRotationMatrix
You transform your 2 rotation matricies to a quaternion. Now you can use D3DXQuaternionSlerp to interpolate between one and the other.
You can then use D3DXMatrixRotationQuaternion to get it back
This is why quaternions are powerful, you can't interpolate between two matricies, but you can convert a matrix to an equivalent quaternion, and interpolate between them.
Some pseudo code would look something like this
D3DXMATRIX StartMatrix; //Where the object startedD3DXMATRIX CurrentMatrix; //Where the object is nowD3DXMATRIX TargetMatrix; //Where the object is goingD3DXQUATERNION startQ,endQ,interpQ;D3DXQuaternionRotationMatrix(&startQ,&StartMatrix);D3DXQuaternionRotationMatrix(&endQ,&EndMatrix);PercentComplete = ((float)(TweenEndTime - TweenStartTime)/1000.0f);D3DXQuaternionSlerp(&interpQ,&startQ,&endQ,PercentageComplete);D3DXMatrixRotationQuaternion(&TargetMatrix,&interpQ);Hope this helps. (I just wrote the code out, I never compiled it, but something like this should work for you)
[edited by - ataru on February 6, 2004 6:03:44 PM]
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