Impz0r 166 Report post Posted March 18, 2002 hi all, I need a litle help to figure out how i can use quaternion for my camera. Currently i calculated the the rotation with my litle quaternion class. This works fine, but i''ve problems to figure out how i can move the camera in that direction in that i''ve rotate it with the quaternion?! I thought, i''ve to add the rotation to the lookat vector, but i don''t exactly know how i''ve to do this *sigh*. Here is the code snipped that i''ve used without quaternion : VOID cCamera::Rotate (Float32 X, Float32 Y, Float32 Z) { cVector3 kView (m_kLockAt.X - m_kPosition.X, m_kLockAt.Y - m_kPosition.Y, m_kLockAt.Z - m_kPosition.Z); // here is the quaternion code i''ve tryed but won''t work :( /* cVector3 kBlah; m_kQuadAxis.EulerToQuat (X, Y, Z); m_kQuadAxis.ConvertToVector (kBlah); -> But how must i use the rotation for the lookat vector?! */ if (X) { m_kLockAt.Z = (Float32) (m_kPosition.Z + cMath::FSinDeg(X)*kView.Y + cMath::FCosDeg(X)*kView.Z); m_kLockAt.Y = (Float32) (m_kPosition.Y + cMath::FCosDeg(X)*kView.Y - cMath::FSinDeg(X)*kView.Z); } if (Y) { m_kLockAt.Z = (Float32) (m_kPosition.Z + cMath::FSinDeg(Y)*kView.X + cMath::FCosDeg(Y)*kView.Z); m_kLockAt.X = (Float32) (m_kPosition.X + cMath::FCosDeg(Y)*kView.X - cMath::FSinDeg(Y)*kView.Z); } if (Z) { m_kLockAt.X = (Float32) (m_kPosition.X + cMath::FSinDeg(Z)*kView.Y + cMath::FCosDeg(Z)*kView.X); m_kLockAt.Y = (Float32) (m_kPosition.Y + cMath::FCosDeg(Z)*kView.Y - cMath::FSinDeg(Z)*kView.X); } I thought the way to do this should be easy, but i don''t found him *g* pls help. Thanks in advance Mfg Impz0r 0 Share this post Link to post Share on other sites

gtdelarosa 128 Report post Posted March 18, 2002 Here is a formula that might help. It rotates a point ''p'' by a quaternion with scalar part ''s'' and vector part ''v''.p'' = (s^2)p + v(p dot v) + 2s(v cross p) + v cross (v cross p)"p dot v" means to take the dot product of p and v."v cross p" means to take the cross product of v and p.This formula gives you the new vector p'' which is ''p'' after it is rotated by the quaternion. 0 Share this post Link to post Share on other sites

Impz0r 166 Report post Posted March 18, 2002 hi,thanks gtdelarosa, your equation works for me but i run into the next fault *sigh*I use your equation to rotate my lookat vector, this works fine, but when i use this code the view looks after a few rotaions like crap *hmpf* VOID cCamera::Rotate (Float32 X, Float32 Y, Float32 Z){ cQuaternion kQ (X,Y,Z); // calculate the rotation m_kQuadAxis *= kQ; // i don''t know if that correct, if i don''t do this, the camera looks after an rotation immediately to the origin position..damned, but the thing is that after a few rotaions the scene became sickness *g*, it don''t look correctly..dunno how i could explain how does it look like ;D m_kQuadAxis.RotateVector (m_kLockAt);} I hope someone could help me out of this crap *g*Thanks in advanceMfg Impz0r 0 Share this post Link to post Share on other sites

gtdelarosa 128 Report post Posted March 18, 2002 This is what I do in my camera class:void QCamera::YawPitchRoll(float ya, float pa, float ra){ // create a quat from the 3 euler angles Quaternion tmp_q; tmp_q.FromEuler(ya,pa,ra); // extract the scalar s and the vector x,y,z from the quat float s = tmp_q.get_s(); float x,y,z; (tmp_q.get_vector()).get_xyz(&x,&y,&z); // multiply the 3 axes of the camera by x,y,z Point3D xvec = m_U * x; // m_U is the side vector Point3D yvec = m_V * y; // m_V is the lookup vector Point3D zvec = m_N * -z;// m_N is the lookat vector // add these three vectors together to form one vector zvec += xvec + yvec; zvec.get_xyz(&x,&y,&z); // combine this new vector with the scalar s to create // a new quat that is in camera space Quaternion ypr_q(s,x,y,z); // rotate each of the camera axes with this new quat m_N = ypr_q.RotatePt(m_N); m_U = ypr_q.RotatePt(m_U); m_V = ypr_q.RotatePt(m_V);}The function RotatePt is just the formula I gave you before. 0 Share this post Link to post Share on other sites

Impz0r 166 Report post Posted March 18, 2002 hi,thanks for the fast reply, but i couldn''t bring it to work, i don''t know where exactly the error lay, but after a few rotation all vectors aka lookat, up, right , have the value of -1.#IND0 i dunno what i did wrong *damnit*. But this is only when is move the camera out of the world origin (0.0.0).Any idea?!Thanks in advanceMfg Impz0r 0 Share this post Link to post Share on other sites

Nazrix 307 Report post Posted March 18, 2002 quote:Original post by Impz0r hi,thanks for the fast reply, but i couldn''t bring it to work, i don''t know where exactly the error lay, but after a few rotation all vectors aka lookat, up, right , have the value of -1.#IND0 i dunno what i did wrong *damnit*. But this is only when is move the camera out of the world origin (0.0.0).Any idea?!Thanks in advanceMfg Impz0r You may already know but -1.#IND0 means it''s undefined. Trig functions are undefined at certain angles...I''m not sure how to fix that though A CRPG in development...Need help? Well, go FAQ yourself. 0 Share this post Link to post Share on other sites

Impz0r 166 Report post Posted March 19, 2002 hi,damn i hang with the camera, can''t figure out whats wrong So i would ask if someone known a good tutorial about a camera with a use of quaternion?!I would be very happy if you can post me a link or source..whatever Thanks in advanceMfg Impz0r 0 Share this post Link to post Share on other sites