source-engine/materialsystem/stdshaders/WaterCheap_ps11.psh

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2020-04-22 16:56:21 +00:00
ps.1.1
; Get the 3-vector from the normal map
tex t0
; Perform matrix multiply to get a local normal bump. Then
; reflect the eye vector through the normal and sample from
; a cubic environment map.
texm3x3pad t1, t0_bx2
texm3x3pad t2, t0_bx2
texm3x3vspec t3, t0_bx2
mul r0.rgb, t3, c1 ; envmap color * envmaptint
+mov_sat r0.a, v0.a ; Put the cheap water blend factor here
dp3_sat t2, v0_bx2, t0_bx2 ; dot eye-vector with per-pixel normal from t0
; run Fresnel approx. on it: R0 + (1-R0) (1-cos(q))^5 in alpha channel
; NOTE: This is not perspective-correct and results in strange artifacts
mul r1.a, 1-t2.a, 1-t2.a ; squared
mul r1.a, r1.a, r1.a ; quartic
mul_sat r1.a, r1.a, 1-t2.a ; quintic
; t1.a is now the fresnel factor
add_sat r0.a, r1.a, r0.a ; Now we have the final blend factor between cheap water + refraction