equalweightcombine.nvp

游戏编程精华02－含有几十个游戏编程例子

/************************************************************************
EqualWeightCombine.nvp

Simple pixel shader that samples all 4 texture stages, averages these
samples and outputs the result.

Copyright (C) 1999, 2000 NVIDIA Corporation
*************************************************************************/


#include "PixelConstants.h"


; Declare pixel shader version
ps.1.1

; Set c0  to 1/8 in setup code for equal weighting


; get colors from all 4 texture stages
tex t0
tex t1
tex t2
tex t3

; and average them according to weights in constant mem:
; r0 = fac * t0 + fac * t1 + fac * t2 + fac * t3
mul r0, c[PCN_MULTFACTOR], t0
mad r1, c[PCN_MULTFACTOR], t1, r0
mad r0, c[PCN_MULTFACTOR], t2, r1
mad r0, c[PCN_MULTFACTOR], t3, r0