dot3_point_atten.nvv

来自「游戏编程精华02－含有几十个游戏编程例子」· NVV 代码 · 共 37 行

; Calculates the range to the light in x,y,z and stores
; these in the texture coordinates.
; This will generate an attenuated texturemap
#include "dot3.h"

#define V_POSITION v0
#define POSITION_WORLD r3
#define LIGHT_DIRECTION r4

vs.1.0

; Transform position to clip space and output it
dp4 oPos.x, V_POSITION, c[CV_WORLDVIEWPROJ_0]
dp4 oPos.y, V_POSITION, c[CV_WORLDVIEWPROJ_1]
dp4 oPos.z, V_POSITION, c[CV_WORLDVIEWPROJ_2]
dp4 oPos.w, V_POSITION, c[CV_WORLDVIEWPROJ_3]

; transform position to world space
dp4 POSITION_WORLD.x, V_POSITION, c[CV_WORLD_0]
dp4 POSITION_WORLD.y, V_POSITION, c[CV_WORLD_1]
dp4 POSITION_WORLD.z, V_POSITION, c[CV_WORLD_2]
dp4 POSITION_WORLD.w, V_POSITION, c[CV_WORLD_3]

; Calculate the vector to the light from the world vertex
add LIGHT_DIRECTION, POSITION_WORLD, -c[CV_LIGHT_POSITION]
mul LIGHT_DIRECTION, LIGHT_DIRECTION, c[CV_ONE_OVER_LIGHT_RANGE].x
add LIGHT_DIRECTION, LIGHT_DIRECTION, c[CV_HALF].x

; output tex coord.  We use the same attenuation map for xy and z
mov oT0.xy, LIGHT_DIRECTION.xy
mov oT1.x, LIGHT_DIRECTION.z
mov oT1.y, c[CV_HALF].x

; Put the light color in diffuse
mov oD0, c[CV_LIGHT_COLOR]