Hi all,

I tried to learn everything about quaternions and matrices the past weeks and solved the loved gible lock now.

When I try to move in 3D space I have now a new problem.

My quaternion code is based on nehe’s gametutorial 7 and some articles from gameasutra and gamedev, because the gametut. 7 is not very intuitive…

So what I’m going to do is to get the direction vector from the quaternion.

I modyfied the gametut. function so looks a bit different but that shouldn’t matter:

`MFVector3D MFQuaternion::GetDirectionVector() { MFVector3D v3dTmp; Normalize(); v3dTmp.x = 2.0f*(x*z-w*y); v3dTmp.y = 2.0f*(y*z+w*x); v3dTmp.z = 1.0f-2.0f*(x*x+y*y); return v3dTmp; } I dont really know what the hack is wrong with this. Maybe its not a mistake made here, so lets see another snip of code: MFQuaternion &MFQuaternion::Set(float xT, float yT, float zT) { MFQuaternion xQ(xT, 1.0f, 0.0f, 0.0f); MFQuaternion yQ(yT, 0.0f, 1.0f, 0.0f); MFQuaternion zQ(zT, 0.0f, 0.0f, 1.0f); *this = xQ; *this *= yQ; *this *= zQ; return *this; } MFQuaternion &MFQuaternion::Set(float angle, float xT, float yT, float zT) { float factor = xT*xT+yT*yT+zT*zT; if(!factor) factor = (float) EPSILON; float scaleBy = (float) (1.0/sqrt(factor)); w = (float) cos(angle/2.0f); float sinHalfAngle = (float) sin(angle/2.0f); x = xT*scaleBy*sinHalfAngle; y = yT*scaleBy*sinHalfAngle; z = zT*scaleBy*sinHalfAngle; return *this; } MFQuaternion MFQuaternion: :operator* (const MFQuaternion Q) { MFQuaternion Qtmp; Qtmp.x = w*Q.x + x*Q.w + y*Q.z - z*Q.y; Qtmp.y = w*Q.y + y*Q.w + z*Q.x - x*Q.z; Qtmp.z = w*Q.z + z*Q.w + x*Q.y - y*Q.x; Qtmp.w = w*Q.w - x*Q.x - y*Q.y - z*Q.z; return Qtmp; } void MFQuaternion: :operator*=(const MFQuaternion Q) { MFQuaternion Qtmp; Qtmp.x = w*Q.x + x*Q.w + y*Q.z - z*Q.y; Qtmp.y = w*Q.y + y*Q.w + z*Q.x - x*Q.z; Qtmp.z = w*Q.z + z*Q.w + x*Q.y - y*Q.x; Qtmp.w = w*Q.w - x*Q.x - y*Q.y - z*Q.z; x = Qtmp.x; y = Qtmp.y; z = Qtmp.z; w = Qtmp.w; } My rotation is applied as follows: rotX = -mouse.y / 500; // Mouse Look rotY = -mouse.x / 500; // Mouse Look // rotZ += 0.001*Engine.Tools->procPower; qRotation *= MFQuaternion(rotX, rotY, rotZ); // qRotation.QuatToAxisAngle(axisX, axisY, axisZ, rotAngle); mRotation = qRotation.QuatToM4(); glMultMatrixf(mRotation.v); // glRotatef((float) (rotAngle*PIUNDER180), axisX, axisY, axisZ); v3dDirection = qRotation.GetDirectionVector(); qRotationT = qRotation; qRotation = MFQuaternion(0.0f, 90.0f, 0.0f) * qRotation; v3dRight = qRotation.GetDirectionVector(); qRotation = qRotationT; qRotation = MFQuaternion(90.0f, 0.0f, 0.0f) * qRotation; v3dUp = qRotation.GetDirectionVector(); qRotation = qRotationT;`

The direction vectors I get are not orthogonal. They seem to be messed up when I rotate the camera (I have a little coordinate System on my screen [thanks to vincoof] so I can see what happend to them).

Maybe someone can find the mistake or you can help with ideas…

Regards,

McNugget

[This message has been edited by McNugget (edited 05-10-2003).]