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Old Feb 28, 2002, 12:06 AM   #1
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pav
Radeon R520
 
Join Date: Feb 2001
Location: Israel Israel
Posts: 381
pav is still being judged by the masses


Default Dot Product! help!!

hi guys...
it's like this...
i know what a dor product is...an operation that
returns the angle between 2 vectors...right?

it's whether
A . B = Ax*Bx + Ay*By
or
A . B = |A|*|B|*Cos(angle)
so if i wanna find the angle between the vectors A and B:

Cos(angle) = (A . B)/(|A|*|B|) so the angle is the inverse of Cos(angle)..

this is all completely clear to me (same for Cross Product)

but what exactly is DotProduct3? or DotProduct4?
you know..the dp3 and dp4 in pixel shaders?

what do the 3 & 4 stand for, what do they mean..

thanx
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