normalmapcreate.nvp

游戏编程精华02－含有几十个游戏编程例子

/*********************************************************************NVMH2****
Path:  C:\Dev\devrel\Nv_sdk_4\Dx8\NVEffectsBrowser\Effects\CA_Water
File:  NormalMapCreate.nvp

Copyright (C) 1999, 2000 NVIDIA Corporation
This file is provided without support, instruction, or implied warranty of any
kind.  NVIDIA makes no guarantee of its fitness for a particular purpose and is
not liable under any circumstances for any damages or loss whatsoever arising
from the use or inability to use this file or items derived from it.

Comments:

Neighbor-differencing for RGB normal map creation.  Scale factors for s and t
  axis components are hard-coded in the constants.  This does a crude
  1-s^2-t^2 calculation for the blue component in order to approximately normalize
  the RGB normal map vector.  For s^2+t^2 close to 1.0, this is a close
  approximation to blue = sqrt(1 - s^2 - t^2) which would give a normalized 
  vector

******************************************************************************/




#include "PixelConstants.h"


; Declare pixel shader version
ps.1.1


// red mask for s axis component
def c5, 1.0, 0.0, 0.0, 1.0

// green mask for t axis component
def c6, 0.0, 1.0, 0.0, 1.0

// blue mask for r axis component (blue = up out of texture)
def c4, 0.0, 0.0, 1.0, 1.0


def c2, 0.5, 0.5, 0.0, 0.0
def c1, 1.0, 1.0, 0.0, 0.0


; get colors from all 4 texture stages
; t0 = -s,  0
; t1 = +s,  0
; t2 =  0, +t
; t3 =  0, -t



tex t0
tex t1
tex t2
tex t3


sub_x4  r0, t0, t1			// (t0 - t1)*4  : 4 for higher scale
mul     t0, r0, c5			// t0 = s result in red only

sub_x4  r1, t3, t2			// r1 = t result in green only

mad     r0, r1, c6, t0      // r0 = red,green for s and t result

mul_x2  t1, r0, r0          // t1 = ( 2 * s^2, 2 * t^2, 0.0)

dp3_d2  r1, 1-t1, c1        // ( 1-2s^2 + 1-2t^2 )/2 = 1 - s^2 - t^2

add     r0, r0, c2          // bias red,green to 0.5

mad     r0, r1, c4, r0      // RGB = (r+0, g+0, 0+blue )