   Particle engine: reverse rotation
  I am programming a new particle engine to work with my new camera class. This new camera class doesn''t store the rotations anymore but instead works directly on the modelview matrix.When drawing the particles I need to orient them towards the camera. How can I rotate the particles towards the camera using only the modelview matrix info? I would really prefer a fast routine since I need to have *lots* of particles.Thanks in advance!    Sander Maréchal[Lone Wolves Game Development][RoboBlast][Articles][GD Emporium][Webdesign][E-mail]
  the modelview matrix, isn''t one row = up vector, another row = right vector, third row = direction vector ?the simplest way is to use the up vector as y-axis and right vector as x-axis for your bilboard  "No lies of sugar can sweeten the sournes of reality"}+TITANIUM+{ A.K.A. DXnewbie[onMIRC]  ;  As Seriema said, you can extract the axes directly from the view matrix. If you''re using D3D..m_pD3Ddevice->GetTransform( D3DTS_VIEW, &viewMatrix);Xaxis.x=viewMatrix._11;Xaxis.y=viewMatrix._21;Xaxis.z=viewMatrix._31;Yaxis.x=viewMatrix._12;Yaxis.y=viewMatrix._22;Yaxis.z=viewMatrix._32;Zaxis.x=viewMatrix._13;Zaxis.y=viewMatrix._23;Zaxis.z=viewMatrix._33;  The method for OGL would be similar. Then you use the x-axis and y-axis as offsets for the corners of each billboard.  ;  Ahhhhh.... stupid, stupid me Why could I not think of that myself. It makes sooo much sence and I knew that those vectors were storen in the modelview matrix.Thanks a lot guys!One last question: The vectors stored in the modelview matrix (OpenGL), are they already normalized? Or would I need to do that manually?    Sander Maréchal[Lone Wolves Game Development][RoboBlast][Articles][GD Emporium][Webdesign][E-mail]