Calculating scissors for test with attenuated light?

OpenGL OpenGL: Advanced Coding
1

Hello.
I am doing stencil shadows and read about the scissor test quite often.
I also read an article on gamasutra. The way they calculate the scissors leaves me confused, though. Can someone maybe help and tell me what I really need. Maybe there is some demo that does this and wich I can look at?
Thanks for the help!

2

http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/009252.html

– Tom

3

Yes, I read about that, too.
But it seems to be a bit special, doesn’t it?
Computing scissors for every object or so it says.
Well, I will have look at it. Thanks!

EDIT:
“the scissor rectangle for the light bounds is rendered in blue”
-Is that what I am looking for? I’ll have to check it out.

[This message has been edited by B_old (edited 04-15-2003).]

4

Doing a scissor for each object saves a whole lot more fill rate than doing it for each light. But scissoring for each light is still way better than not scissoring at all. This new(?) technique is pretty darn cool IMHO.

-SirKnight

5

Yes, but first of all I have to get this per-light scissor test working properly. That is, it is not working at all at this time.
I’ll be away for a week now. I hope I can manage to put it in then when I am back.
SirKnight, do you know how to calculate the scissors for the light?

Thanks all for the help!

6

Originally posted by B_old:
[b]Yes, but first of all I have to get this per-light scissor test working properly. That is, it is not working at all at this time.
I’ll be away for a week now. I hope I can manage to put it in then when I am back.
SirKnight, do you know how to calculate the scissors for the light?

Thanks all for the help![/b]

B_old,

You transform the bounding volume for the light into window coordinates. Have you seen the demo on the NVIDIA developer site (http://developer.nvidia.com/)?

Thanks -
Cass