applyvelocityshader.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\Dot3Bump_Dynamic
File:  ApplyVelocityShader.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:

This shader samples t1, biases its value to a signed number, and applies this
value multiplied by a scale factor to the t0 sample.

This is used to apply a "velocity" texture value to a "height" state texture
for nearest-neighbor height-based water simulations.  The output pixel is
the new "height" value to replace the t0 sample in rendering to a new 
texture which will replace the texture selected into t0.

A nearlty identical shader using a different scaling constant is used to
apply the "force" value to the "velocity" texture at each texel.

t1 comes in the range [0,1] but needs to hold signed values, so a value of
0.5 in t1 represents zero velocity.  This is biased to a signed value in 
computing the new position.


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


#include "PixelConstants.h"


; Declare pixel shader version
ps.1.1


; t0 = height field
; t1 = velocity          


tex t0      // previous position
tex t1      // velocity at texel being updated


; Bias the force/velocity to a signed value so we can subtract from
;   the t0 position sample.

; New height = velocity * scale factor + old height

mad  r0, t1_bias, c[PCN_MULTFACTOR_1], t0