Bullet physics 4x4 matrix problem

Hi, i'm trying to integrate Bullet physics in my project, I got it working, but I'm not sure how to translate the transformation of physical objects, to the 3D models.

Bullet uses this function to store the transformations of objects in a Matrix, then pass it to the 3d model:

btRigidBody-> getWorldTransform ().getOpenGLMatrix(Matrix);

But there is a problem, OpenGL uses 4x4 matrix (float [16]) and Gx uses 3x4 matrix, and i don`t know how to convert that array from 4x4 to 3x4.

Anyone know how I could solve this problem?

Thanks in advance :)

I've never really thought about what a matrix is all about, you post made me think about it.
You will know this but I had no idea, anyway I found out the that GX Mtx[3][4] is able to translate and rotate, having a vector for each x,y,z axis & a vector for translation if I understand things.

So any idea what the extra vector in the GL 4x4 does?
Maybe it's possible to just drop it the extra part? If it's used say for perspective, I guessing instead you might need to 'guMtxConcat' the cut down matrix with with the camera matrix instead.

How come you’re using openGL for the Wii platform

Thanks, I've solved, it was not so complicated after all xD actually the 4x4 matrix is only a 3x4 matrix with some extra vectors that bullet physics do not use , so the only thing to do is find out the position vector x, y, z, the scale vector, etc... in each type of matrix,

This is what I've done:

f32 worldMat[16]; //the 4x4 matrix
Mtx m; // 3x4 matrix

obj->_btRigidBody->getWorldTransform().getOpenGLMatrix(worldMat); 

//Then copy all the values ??to the  3x4 array in this order

        m[0][0]=worldMat[0];
	m[1][0]=worldMat[1];
	m[2][0]=worldMat[2];
	
	m[0][1]=worldMat[4];
	m[1][1]=worldMat[5];
	m[2][1]=worldMat[6];
	
	m[0][2]=worldMat[8];
	m[1][2]=worldMat[9];
	m[2][2]=worldMat[10];
	
	m[0][3]=worldMat[12];
	m[1][3]=worldMat[13];
	m[2][3]=worldMat[14];

And that's all, is not very nice, but it works perfectly :D

PS: i`m not using opengl, was only, that function, uses typical matrices of OpenGL :)



Edited 1 time(s). Last edit at 07/21/2011 09:04PM by copete23.