RE: [Algorithms] Bullets on walls

[Jay S. <Ja...@va...>]

This was the first thing I tried for the bullet holes in Half-Life.  It's
really, really slow.  Once you have 3 or 4 bullet holes on a wall and a
player walks up to the wall you are redrawing the entire screen 5 or 6 times
(or more if you have complex materials).  This just doesn't scale if you
expect to have several decals on a single surface.  It's much better to clip
the decal polygons and draw them with polygon offset.

Jay

> -----Original Message-----
> From: Jaimi McEntire [mailto:ja...@al...]
> Sent: Thursday, July 20, 2000 1:01 PM
> To: gda...@li...
> Subject: RE: [Algorithms] Bullets on walls
> 
> 
> In d3d, this is the way I do it:
> 
> Create decals with a one pixel transparent border.
> Then, set the texture address mode to "Clamp".
> Calculate new UV coordinates for your decal based on the wall, instead
> of the Decal - then redraw the entire wall with your decal texture and
> new UV coordinates.
> This way you do not have to clip at all. I would assume you could
> do the same in OpenGL.
> 
> Jaimi
> 
> -----Original Message-----
> From: gda...@li...
> [mailto:gda...@li...]On Behalf Of
> Tiziano Lena
> Sent: Thursday, July 20, 2000 2:19 PM
> To: gda...@li...
> Subject: [Algorithms] Bullets on walls
> 
> 
> Hi!
> I added wallmarks in my 3d engine but when I fire on the 
> border of a wall I
> would like to clip the wallmark to the wall.
> 
> I have some ideas but I think they are a bit slow... (manual clipping,
> texgen, stencil?)
> 
> How do you do this?
> 
> Thanks for any help!
> 
> 
> 
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