fix background

OpenGL OpenGL: Basic Coding
1

I try to draw the coordinate system, x,y,z axis on the screen and want to freeze that there, and when I rotate an object like a square(vertex(1.0)…) the coordinate system stay the same, just the square get rotate,translate and scale? I try but it’s rotate the axis(make by vertex3f) also… Any one got any idea, how to do that ? thx

2

Just draw the axis before you do the rotations/translations. Remember, rotations/translations apply only to objects drawn thereafter.

Morglum

3

I tried but it’s didn’t visible, how come?

4

Maybe you’ve drawn the axis too early… Your rendering code should look like :

void display_scene ()
{
glClear (… //and other pre-render stuff
glLoadIdentity (); // This must be done before drawing anything - even the axis
draw_the_axis ();

glTranslatef(… //translation applied to the object

glRotatef(… // rotation applied to the object

draw_the_object ();

swap_buffers (); // or any other post-render stuff

}

5

Yeah, the way Morglum said would work… But you could also call glLoadIdentity() right before drawing your axis…

so

glLoadIdentity();
rotate();
.
.
draw stuff

glLoadIdentity()
darwAxis();