Hello,
maybe it’s a stupid question, but there something confusing me.
Do I have to set the projection matrix to identity as well ?
Usually I do the following to draw a quad that covers the entire
viewport.
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glBegin(GL_QUADS);
glVertex3f(-1.0f,-1.0f, -1.0f);
glVertex3f( 1.0f,-1.0f, -1.0f);
glVertex3f( 1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glEnd();
glPopMatrix();
for creating the projection i use the gluPerspective
with following values:
gluPerspective(90.0f, w/h, 1.0f, 100.0f);
For this settings the fullscreen quad does not cover the
entire viewport. I have borders on the right and left side.
But if the fovy is something below 50.0f then the quad fits the viewport.
So why does it happen ? On opengl.org there is an example drawing a fullscreen quad. they don’t mention to change the
projection matrix.
regards,
lobbel