Orthogonal projection and texture coordinates in opengl
- by knuck
I'm writing a 2D game in Opengl. I already set up the orthogonal projection so I can easily know where a quad will end up on screen. The problem is, I also want to be able to map pixels directly to texture coords, so I also applied an orthogonal transformation (using gluOrtho2d) to the texture. Now I can map pixels directly using integers and glTexCoord2i. The thing is, after googling/reading/asking, I found out no one really knows (apparently) the behavior of glTexCoord2i, but it works just fine the way I'm using. Some sample test code I wrote follows:
glBegin(GL_QUADS);
glTexCoord2i(16,0);
glVertex2f(X, Y);
glTexCoord2i(16,16);
glVertex2f(X, Y+32);
glTexCoord2i(32, 16);
glVertex2f(X+32, Y+32);
glTexCoord2i(32, 0);
glVertex2f(X+32, Y);
glEnd();
So, is there any problem with what I'm doing, or is what I'm doing correct?
