Relationship between coordinates

Search for projection matrices, once you have read up about it, you should be able to figure it out for yourself.

Thanks AP I''ve looked into the glOrtho() function and I''ve managed to do what I wanted. However I''m a bit surprised with the texture mapping in this mode. Indeed, I''ve mapped a 128*128 pixels texture on a 128*128 pixels square (I know it''s exactly this size thanks to the glOrtho() function) and my texture is *not* filtered, even though I''ve specified a linear filtering. In fact that''s great becasue that''s what I wanted, however I''m wondering why it''s not been filtered. Because it is rendered at its original size? Is it a feature or a bug?

What shall get filtered? In this context filtering is just used to do a texel <-> pixel conversion. When a pixel doesn''t line up with a texel you get an weighted average value of the affected texels. But if a pixel is lined up with a texel you get the pixel will have the texel''s color.