Camera "gluperspective" question?

OpenGL Development
#1

i’m trying to make a 3d game with a birds eye 2d view during gameplay, i have set the view as follows:-

//      Calculate The Aspect Ratio Of The Window, 3d camera
        GLU.gluPerspective(
                  45.0f,
                  (float)640 / (float) 480, // these being screen width and height
                  0.1f,
                  1000.0f);
                GL11.glMatrixMode(GL11.GL_MODELVIEW); // Select The Modelview Matrix
                
                GL11.glLoadIdentity();
                
                GLU.gluLookAt(320.0f,240.0f,600.0f,  // camera pos
                                                     320.0f,240.0f,0.0f, // camera target
                                                         0.0f,1.0f,0.0f); // camera tilt

i have a box in the middle of the screen, the thing is when the object moves left or right on the screen i begin to see the sides of the object the futher it moves away from the centre of the screen, i know this is normal for 3d but i was hopeing if there was a way to reduce this so the sides don’t show so much and i get more of a 2d style feel?

thx

#2

If you don’t want any 3d effect you can use ortho mode. If you wan’t to reduce the 3d effect you reduce the first parameter to gluPerspective. Try 45.5f/2f as an example. This will give you a narrower frustum and you will look like it was zoomed in. To overcome this you have to move the camera back to compensate.

edit: You could also look at glFrustum for a different way of setting up the perspecive projection.

#3

yeah i just want to reduce the 3d effect, i’ll try that. :wink:

#4

i’ve got the sort of angle i was after about 10, but the thing is i have to nearly zoom the camera back by like 3000.0f units, would this have any impact on the overall performance or is it ok, if it does is there a better way to achieve this?

thanks

#5

There is no speed penalty, but you must remember to increase the near clipping plane or you can end up with lack of precision in the z buffer. You could try setting the near clipping plane to 1000.