I've been looking for some algorithm for camera movements and i came across the nehe's quaternion camera class. I've read the tutorial and played with the code and i've noticed that the orientation is: x-axis is left to right, y-axis is top to bottom, and z-axis is front to back. But the orientation i need is: x-axis is left to right, y-axis is front to back, and z-axis is top to bottom. I thought the fix would be simple, so i changed the CreateFromAxisAngle(&cam->m_qHeading,0.0f, 1.0f, 0.0f, cam->m_HeadingDegrees); to CreateFromAxisAngle(&cam->m_qHeading,0.0f, 0.0f, 1.0f, cam->m_HeadingDegrees); but i can't find the correct direction vector from the algorithm. I've been trying for a day and i've pretty much in dispair. Can anyone look at my code and give me any type of advice or some kind of insight? void SetPrespective(glCamera *cam) { GLfloat Matrix[16]; glQuaternion q; // Make the Quaternions that will represent our rotations CreateFromAxisAngle(&cam->m_qPitch,1.0f, 0.0f, 0.0f, cam->m_PitchDegrees); CreateFromAxisAngle(&cam->m_qHeading,0.0f, 0.0f, 1.0f, cam->m_HeadingDegrees); // Combine the pitch and heading rotations and store the results in q q = QuaternionMultiply(&cam->m_qPitch,&cam->m_qHeading); CreateMatrix(&q,Matrix); // Let OpenGL set our new prespective on the world! glMultMatrixf(Matrix); // Create a matrix from the pitch Quaternion and get the j vector // for our direction. CreateMatrix(&cam->m_qPitch,Matrix); cam->m_DirectionVector.j = Matrix[9]; // Combine the heading and pitch rotations and make a matrix to get // the i and j vectors for our direction. q = QuaternionMultiply(&cam->m_qHeading,&cam->m_qPitch); CreateMatrix(&q,Matrix); cam->m_DirectionVector.i = Matrix[8]; cam->m_DirectionVector.k = Matrix[10]; // Scale the direction by our speed. cam->m_DirectionVector.i *= cam->m_ZoomVelocity; cam->m_DirectionVector.j *= cam->m_ZoomVelocity; cam->m_DirectionVector.k *= cam->m_ZoomVelocity; // Increment our position by the vector cam->m_Position.x += cam->m_DirectionVector.i; cam->m_Position.y += cam->m_DirectionVector.j; cam->m_Position.z += cam->m_DirectionVector.k; cam->m_ZoomVelocity = 0.f; if(cam->m_Position.y<boundary3DHeight){ AdjustElevation(cam); } glTranslatef(-cam->m_Position.x, -cam->m_Position.y, -cam->m_Position.z); } //Quaternion Section void CreateFromAxisAngle(glQuaternion *quat,GLfloat x, GLfloat y, GLfloat z, GLfloat degrees){ // First we want to convert the degrees to radians // since the angle is assumed to be in radians GLfloat angle = (GLfloat)((degrees / 180.0f) * PI); // Here we calculate the sin( theta / 2) once for optimization GLfloat result = (GLfloat)sin( angle / 2.0f ); // Calcualte the w value by cos( theta / 2 ) quat->w = (GLfloat)cos( angle / 2.0f ); // Calculate the x, y and z of the quaternion quat->x = (GLfloat)(x * result); quat->y = (GLfloat)(y * result); quat->z = (GLfloat)(z * result); } void CreateMatrix(glQuaternion *quat, GLfloat *pMatrix) { // Make sure the matrix has allocated memory to store the rotation data if(!pMatrix) return; // First row pMatrix[ 0] = 1.0f - 2.0f * ( quat->y * quat->y + quat->z * quat->z ); pMatrix[ 1] = 2.0f * (quat->x * quat->y + quat->z * quat->w); pMatrix[ 2] = 2.0f * (quat->x * quat->z - quat->y * quat->w); pMatrix[ 3] = 0.0f; // Second row pMatrix[ 4] = 2.0f * ( quat->x * quat->y - quat->z * quat->w ); pMatrix[ 5] = 1.0f - 2.0f * ( quat->x * quat->x + quat->z * quat->z ); pMatrix[ 6] = 2.0f * (quat->z * quat->y + quat->x * quat->w ); pMatrix[ 7] = 0.0f; // Third row pMatrix[ 8] = 2.0f * ( quat->x * quat->z + quat->y * quat->w ); pMatrix[ 9] = 2.0f * ( quat->y * quat->z - quat->x * quat->w ); pMatrix[10] = 1.0f - 2.0f * ( quat->x * quat->x + quat->y * quat->y ); pMatrix[11] = 0.0f; // Fourth row pMatrix[12] = 0; pMatrix[13] = 0; pMatrix[14] = 0; pMatrix[15] = 1.0f; // Now pMatrix[] is a 4x4 homogeneous matrix that can be applied to an OpenGL Matrix } glQuaternion QuaternionMultiply(const glQuaternion *q1, const glQuaternion *q2) { glQuaternion result; result.w = q1->w*q2->w - q1->x*q2->x - q1->y*q2->y - q1->z*q2->z; result.x = q1->w*q2->x + q1->x*q2->w + q1->y*q2->z - q1->z*q2->y; result.y = q1->w*q2->y + q1->y*q2->w + q1->z*q2->x - q1->x*q2->z; result.z = q1->w*q2->z + q1->z*q2->w + q1->x*q2->y - q1->y*q2->x; return result; } Thanks in advance