gdalgorithms-list

RE: [Algorithms] Real-Time Shadows

[Steve W. <Ste...@im...>]

> From: Pai-Hung Chen [mailto:pa...@ac...]
> 
> Can anyone help me start on how to calculate shadow polygons
> (bounding polygons of the shadow volumne) in the world space?

I guess just a start would be a common suggestion that I've heard for
shadows...drawing just the objects that will create shadows onto a back
surface with the camera positioned to where the light will be that you want
to create shadows for while using a darker texture than what the object
normally has, then blitting that "shadow" into your world.  The drawbacks
are that you have to figure out which objects are in front of which for each
light...not the kind of thing you want to do in real-time, unless you just
have a ceiling light and just want a shadow on the floor from players.

That's about all I know, and I haven't worked out any of the details for it.

R&R

RE: [Algorithms] Real-Time Shadows

[Akbar A. <sye...@ea...>]

there's been a lot of papers and demos on that one.
but here's a hint of advice.
imho, hard shadows are totally nasty and ugly.
point light sources are very rare in real life.
check www.nvidia.com/developer for the nvshadow demo. mark wrote up a paper
on it too.

if you have realtimerendering check the shadow chapter. it gives a very
clear way to do this.
>In my case, I am using Quake II
>models as my characters, each of which is composed of 500~1000 >
>>>>polygons.
looks like you won't be doing to much coding for the shadows.
also check out the quake clone demo on nvidia's site. it takes the quake 2
models' and casts shadows.
including shadow volumes.


peace.
akbar A.



-----Original Message-----
From: gda...@li...
[mailto:gda...@li...]On Behalf Of
Pai-Hung Chen
Sent: Tuesday, July 18, 2000 3:47 PM
To: gda...@li...
Subject: [Algorithms] Real-Time Shadows


Hi,

I am palnning to use traditional Shadow Volume technique to generate dynamic
shadows.  Can anyone help me start on how to calculate shadow polygons
(bounding polygons of the shadow volumne) in the world space?  (I use
Direct3D.)  Also, I am wondering if shadow volume is the right choice for
real-time 3D games to generate shadows.  In my case, I am using Quake II
models as my characters, each of which is composed of 500~1000 polygons.
Can someone in-the-know tell me how shadows are typically generated in 3D
RPG games?

BTW, can someone point me to any tutorials detailing how to calculate
object's silhouette and then build shadow volume from it?

Thank you,

Pai-Hung Chen



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