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Archive Notice: This thread is old and no longer active. It is here for reference purposes. This thread was created on an older version of the flipcode forums, before the site closed in 2005. Please keep that in mind as you view this thread, as many of the topics and opinions may be outdated.
 
Phantom

March 02, 1999, 08:06 AM

cschrett wrote: (I've moved another bit of your text here)
>> yes, about bumpmapping. i know a technique of bumpmapping
>> wich fit especialy for 3d card called displacement maps maybe.
>> see the donut example of 3dfx2 I know nothing about it and
>> I'm looking for informations.
>> what i want is to do is implementing an *free direction* bump
>> mapper in software

Yeah, I've heard about this displacement mapping. It's something
with overlapping polygons with a lightmap that is slightly
displaced, depending on the orientation of the polygon. Looks
like bumpmapping, and might be good enough. I do not have a
VooDoo, so I've never seen the demo...

What do you mean by a free direction software bumpmapper?

 
Colas

March 03, 1999, 05:34 AM



Phantom wrote:


>>What do you mean by a free direction software bumpmapper?

the common demo technique is to use fake envmap.
this method fit perfectly if the lightsource is positioned on the camera
but if the position and direction of the spotlight is random, this is tricky
to obtain good results.

if some1 has more informations on a bumpmapping technique wich work with a standard rasterizer
(no need of deltas computation in the innerloop) the drop me a line please.

Colas


 
Phantom

March 03, 1999, 06:33 AM

Colas wrote:
>> the common demo technique is to use fake envmap.
>> this method fit perfectly if the lightsource is positioned on the camera
>> but if the position and direction of the spotlight is random, this is tricky
>> to obtain good results.
>> if some1 has more informations on a bumpmapping technique wich work with a
>> standard rasterizer (no need of deltas computation in the innerloop) the
>> drop me a line please.

Have you checked my real-time 3D bumpmapping article in the features section?
Let me know if that's what you wanted. If not, also let me know. :)

 
colas

March 04, 1999, 03:08 AM

the pahantom !!

i dislike your bumpmap for two main reason :
the test per pixel if it s lit or not
you use a displacement in the lightmap , err the main advantage of projective texturing is to use
spots of random shapes for example gobos used by the scanners in disco clubs ...
in these case, the lightmap don't goes from bight to dark.

Sorry

Colas :-)

 
Phantom

March 04, 1999, 04:34 AM

colas wrote:
>> the pahantom !!

It's PHANTOM dude... :)

>> i dislike your bumpmap for two main reason :
>> the test per pixel if it s lit or not
>> you use a displacement in the lightmap , err the main advantage
>> of projective texturing is to use spots of random shapes for
>> example gobos used by the scanners in disco clubs ...
>> in these case, the lightmap don't goes from bight to dark.

True, but that's not a problem. Reflecting light from a different
location is precisely what real bumps do. So, if there happens
to be a spot on your disco bitmap, good, if not, good too. :)

Erm... What's the second reason you don't like my bumps?

 
Colas

March 04, 1999, 06:46 AM



>>It's PHANTOM dude... :)

sorry for the typing error

english errors+typing errors, what a mess :-)


>>Erm... What's the second reason you don't like my bumps?

this is the per pixel test
i already use a z buffer, i can not add an test>
if a do that, my performances will trash (lack of registers)

colas

 
Phantom

March 04, 1999, 07:00 AM

Colas wrote:
>>>> Erm... What's the second reason you don't like my bumps?
>>
>> this is the per pixel test
>> i already use a z buffer, i can not add an test>
>> if a do that, my performances will trash (lack of registers)

The bump adjustments do not require extra tests.
You just add a coordinate to the address that you
use to lookup the intensity in the phong map.

In case you run out of registers, just use memory.
On a Pentium and above, reading from level 1 cache
is just as fast as reading from a register.

 
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