shadowmap.psh

real-time(实时渲染技术DirectX)Media

ps.1.1

;Set the bias for the conditional instruction. The instruction
;compares against 0.5.
def c0, 0.495, 0.495, 0.495, 0.495

;If the conditional test passes we want full brightness
def c1, 1.0, 1.0, 1.0, 1.0

;If the test fails, everything is dark
def c2, 0.5, 0.5, 0.5, 0.5

;This is the light texture
tex t0

;Subtract the two distances. The result should be either
;zero or greater than zero.
sub r1, v1, t0

;Add 0.5. If the distances matched the result will be equal
;to 0.5. Otherwise it will be greater
add r0.a, r1.b, c0.b

;Compare the result to 0.5. If the distances don't match, choose c2
cnd r0, r0.a, c2, c1

;r0 is now either zero or one. Use that value to turn
;the lighting on or off.
mul r0, r0, v0