On Sat, Jan 22, 2011 at 3:48 PM, Sam Bull <sam.hack...@sent.com> wrote:
> I only know a tiny bit of OpenGL, and I was wondering if anybody who > knows some OpenGL programming could answer a question, to help me > prepare. > In order for me to produce these widgets in OpenGL, does OpenGL > provide > functions to draw 2D shapes onto the screen in front of the 3D view > (like a HUD), or do these have to be drawn in 3D and anchored to the > camera or something?. > > Thanks, > Sam Bull > Graphics hardware works by transforming points (vertices) by three matrices (model, view, projection, although OpenGL combines the model and view matrices). Then, the points are connected by pixels (rasterization). So yes, change the matrices, and you change how what you see works. To do a 3D view: glMatrixMode(GL_PROJECTION) glLoadIdentity() gluPerspective(...) glMatrixMode(GL_MODELVIEW) glLoadIdentity() gluLookAt(...) #draw world To do a 2D view: glMatrixMode(GL_PROJECTION) glLoadIdentity() glOrtho(...) or gluOrtho2D(...) glMatrixMode(GL_MODELVIEW) glLoadIdentity() #draw HUD Ian
