neighborforcecalc.nvp

来自「游戏编程精华02－含有几十个游戏编程例子」· NVP 代码 · 共 56 行

#include "PixelConstants.h"


; Declare pixel shader version
ps.1.1


; t0 = center
; t1, t2 = 1st axis left to right so force == 
;   t1 - t0 + t2 - t0
; t3 = one point of other axis


def c7, 0.5, 0.5, 0.5, 1.0




; get colors from all 4 texture stages
;  t0 = center texel
;  t1 = 1st neighbor
;  t2 = 2nd neighbor
;  t3 = 3rd neighbor

tex t0
tex t1
tex t2
tex t3


sub r0, t1, t0
sub r1, t2, t0

; 'force' for 1st axis
add r0, r0, r1        

; one more point for 2nd axis
sub r1, t3, t0
add r0, r0, r1

; Now force to restore center texel to 0.5
sub r1, c7, t0
mad r0, r1, c[PCN_EQ_REST_FAC], r0


; shift up to center about 0.5
add r0, r0, c[PCN_ADDHALF]