how to draw on the screen without cleaning others drawn object..?

Dear developers,
My drawing function CView::RenderScene is called on WM_PAINT event.
How can I draw something on the screen without clearing screen(put
OpenGL drawing code outside RenderScene function).


er. I don’t know anything about the windows event model, but i’m guessin’ its similar to X’s event model (and how glut is like a duplo version of it=).

The short answer is:

you can stick gl commands anywhere in your program, and they WILL be rendered (providing you have a current opengl context, of course). you can draw stuff in the reshape callback, for example.

however: you may want to rethink how you’re structurnig your program. do you really need to add drawing code elsewhere? consider this example:

bool clear=true;

void render(void)

void reshape(int w, int h)

this simple example will alternatively clear the screen every time the window is reshaped, but the drawing code still remains in the render fucntion. So, think abouyt your program flow before you get too carried away.


i think what you will do, is only clear the depthbuffer(if you use one), so you can draw over the last frame without clearing it

Also override the OnEraseBkgnd() function and have it simply return TRUE, or windows will try to clear the scene for you.