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JohnWesterman
06-26-2002, 12:44 AM
Why is it when I move either my camera or viewport, the OpenGL selection picking no longer works?

Thanks in Advance

Relic
06-26-2002, 01:28 AM
You probably messed up the matrices.

Or you have not converted the picking position from windows top-left origin to OpenGL's bottom-left?

Have a look at the sample in the gluPickMatrix manual.



When rendering a scene as follows:

glMatrixMode(GL_PROJECTION);
glLoadIdentity( );
gluPerspective(. . .);
glMatrixMode(GL_MODELVIEW);
/* Draw the scene */

the following code selects a portion of the viewport:

glMatrixMode(GL_PROJECTION);
glLoadIdentity( );
gluPickMatrix(x, y, width, height, viewport);
gluPerspective(. . .);
glMatrixMode(GL_MODELVIEW);
/* Draw the scene */

[This message has been edited by Relic (edited 06-26-2002).]