how to size screen according to geometry

[Wizumwalt]

I’m reading grids, lines, etc… from a file and when I display them, they are not showing up on the screen. So I think there being drawn offscreen?!

So how do I know how to size the screen? Like, is it something to do w/ the viewing or modeling translation (I have the red book but it’s still not clear to me)?

Any big hints or help, thnxs.

Will

[ribot]

If you are working in a 2D orthographic mode (HUD, GUI etc…) you should use something like the following:

  public void reshape(GLDrawable drawable, int x, int y, int width, int height) {
        gl = drawable.getGL();
        if (height <= 0) // avoid a divide by zero error!
              height = 1;
              
        // Update the class wide screensize variables
        screenWidth = width;
        screenHeight = height;
        
        gl.glViewport(0, 0, width, height);
        gl.glMatrixMode(GL.GL_PROJECTION);
        gl.glLoadIdentity();
        gl.glOrtho(0.0f, width, 0.0f, height, 0.0f, 10000.0f);  // this being the most important line!
        gl.glMatrixMode(GL.GL_MODELVIEW);

        gl.glLoadIdentity();
  }

if width and height are set to 800 and 600 respectively, you can then use gl.glVertex3f() with specific locations in the 800 by 600 area. For example. a line from point 100, 200 to 700, 300 would use vertex calls like the following:

gl.glBegin(GL.GL_LINES);
gl.glVertex3f(100.0f, 200.0f, 0.0f);
gl.glVertex3f(700.0f, 300.0f, 0.0f);
gl.glEnd()

Hope this helps.