View Full Version : Perspective `zoom' - where did it go?
04-20-2002, 01:00 PM
Some time ago someone posted a tutorial for executing a zoom operation on a scene (calculating fov etc. from a rectangular area drawn out on the screen) - I can't find the tut anywhere now.
Can someone point me in the correct direction please?
04-22-2002, 12:29 AM
this can be done using the stencil buffer as following
1. Render to stencil, not to frame buffer the shape of you zoom, a sphere or a quad
setup the stencil buffer so that it write a 1 where it rendered
2. Render your scene with normal fov but enable stenciltest so that it fails where the stencil is 1
3. Render your scene with zoomed fov but enable stenciltest so that it succeds where the stencil is 1
[This message has been edited by ScottManDeath (edited 04-22-2002).]
04-22-2002, 03:03 AM
Rectangles are also perfect candidates for the scissor test, so you don't need to mess with the stencil buffer.
1)Disable scissor test
2)set normal projection
3)Draw non-zoomed stuff
4)set scissor rectangle
5)enable scissor test
7)set up 'zoom' projection
8)render zoomed stuff
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