Get the camera position in opengl

Question

I know that in opengl that the camera doesn't move, but the model is moving around it. Well I need the position of the camera in MODELVIEW... Yes, I also know that there is many topics about it but I tried all what they are doing to get the camera coordinates but it always returns (0, 0, 0) (the real position of the camera).

This is what i'm trying :

GLfloat mdl[16];
float camera_org[3];
glMatrixMode( GL_MODELVIEW );
glPushMatrix();
glGetFloatv(GL_MODELVIEW_MATRIX, mdl);
camera_org[0] = -(mdl[0] * mdl[12] + mdl[1] * mdl[13] + mdl[2] * mdl[14]);
camera_org[1] = -(mdl[4] * mdl[12] + mdl[5] * mdl[13] + mdl[6] * mdl[14]);
camera_org[2] = -(mdl[8] * mdl[12] + mdl[9] * mdl[13] + mdl[10] * mdl[14]);

also tried this (as said in some topics) :

camera_org[0] = mdl[12];
camera_org[0] = mdl[13];
camera_org[0] = mdl[14];

both of them gives me the same result (0,0,0), can anyone please tell me what i'm doing wrong ??

This very much sounds like you are trying to do something that def is wrong idea to try to do. You probably should rethink what you actually try to archive and if there was better alternative. To have something sane in GL matrix stack you would need to set it your self. — Pauli Nieminen
I found a better way to do it, I posted the answer, thank you ! — Othman Benchekroun
Actually there's no camera at all in OpenGL. If you have a camera object in your logic, then get its position from there. Do not treat OpenGL like a scene graph, because OpenGL is not a scene graph. — datenwolf

Othman Benchekroun Othman Benchekroun · Accepted Answer · 2014-08-27T13:11:28

I found the answer for this :

int viewport[4]; 
// get matrixs and viewport:
glGetDoublev( GL_MODELVIEW_MATRIX, matModelView ); 
glGetDoublev( GL_PROJECTION_MATRIX, matProjection ); 
glGetIntegerv( GL_VIEWPORT, viewport ); 
gluUnProject( (viewport[2]-viewport[0])/2 , (viewport[3]-viewport[1])/2, 
0.0, matModelView, matProjection, viewport,  
&camera_pos[0],&camera_pos[1],&camera_pos[2]);

this will give you the coordinates of the camera in the scene.

Get the camera position in opengl

1 Answers