calculating the range of view

[middy]

Here is the situation

I am drawring up a solar system. They are all been drawed along the xaxis(its a simple selection screen).

My camera is positioned at (0,0,-70).

That means I can see a range of -45 to 45 on the xaxis in world coords. I found that out by trying.

So
How do I measure my range?

and how do I change my frustrum so I can view more/less

[cfmdobbie]

Depends on your viewing transformation - if you're using an orthographic projection you provide min/max values in the glOrtho call, with perspective you provide a field of view argument yourself, but you're using a frustum, yes?

You should be able to work out the field of view using trigonometry - draw a picture of your viewing volume from above and work out the angle of separation between the two sides using the size of the virtual screen and your distance to it.

[middy]

public void viewFrom(){
	
		
		GLU.gluLookAt(_position._x,_position._y,_position._z,_view._x,_view._y,_view._z,_top.getX(),_top.getY(),_top.getZ());
		
		//GL.glViewport(0,0,800,600);
		GL.glMatrixMode(GL.GL_PROJECTION);
		GL.glLoadIdentity();
		GLU.gluPerspective(90,this._aspect,this._minDepth,this._maxDepth);
		GL.glMatrixMode(GL.GL_MODELVIEW);
	
	}