Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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vs.1.1
# DYNAMIC: "DOWATERFOG" "0..1"
#include "macros.vsh"
$cQuarter = "c91.x";
;------------------------------------------------------------------------------
; Constants specified by the app
; c0 = (0, 1, 2, 0.5)
; c1 = (1/2.2, 0, 0, 0)
; 2 = camera position *in world space*
; c4-c7 = modelViewProj matrix (transpose)
; c8-c11 = ViewProj matrix (transpose)
; c12-c15 = model->world matrix (transpose)
; c16 = [fogStart, fogEnd, fogRange, undefined]
; c17-c20 = model->view matrix (transpose)
;
; The ParticleSphere lighting equation is:
; A + [N dot ||L - P||] * C * r / |L - P|^2
;
; where:
; A = ambient light color
; N = particle normal (stored in the texture)
; L = directional light position
; P = point on surface
; C = directional light color
; r = directional light intensity
;
; This shader just does the |L - P| part and the pixel shader does the rest.
;
; Vertex components
; $vPos = Position
; $vSpecular = Directional light color
; $vColor = Ambient color (and alpha)
; $vTexCoord0 = Texture coordinates for normal map
; $vTexCoord0.z = Index into the light list for light info
;------------------------------------------------------------------------------
; Constant registers
;------------------------------------------------------------------------------
;------------------------------------------------------------------------------
; Vertex blending
;------------------------------------------------------------------------------
&AllocateRegister( \$projPos );
; Transform position from object to projection space
dp4 $projPos.x, $vPos, $cModelViewProj0
dp4 $projPos.y, $vPos, $cModelViewProj1
dp4 $projPos.z, $vPos, $cModelViewProj2
dp4 $projPos.w, $vPos, $cModelViewProj3
mov oPos, $projPos
;------------------------------------------------------------------------------
; Fog
;------------------------------------------------------------------------------
alloc $worldPos
if( $DOWATERFOG == 1 )
{
; Get the worldpos z component only since that's all we need for height fog
dp4 $worldPos.z, $vPos, $cModel2
}
&CalcFog( $worldPos, $projPos );
free $worldPos
&FreeRegister( \$projPos );
;------------------------------------------------------------------------------
; Setup to index our directional light.
;------------------------------------------------------------------------------
mov a0.x, $vTexCoord0.z
;------------------------------------------------------------------------------
; Copy texcoords for the normal map texture
;------------------------------------------------------------------------------
mov oT0, $vTexCoord0
mov oT2.xyz, $vColor
; FIXME : the rest of this needs to use AllocateRegister
;------------------------------------------------------------------------------
; Generate a tangent space and rotate L.
; This can be thought of as rotating the normal map to face the viewer.
;
; This is useful when a particle is way off to the side of the screen.
; You should be looking at the half-sphere with a normal pointing from the
; particle to the viewer. Instead, you're looking at the half-sphere with
; a normal along Z. This tangent space builder code fixes the problem.
;
; Note that since the model and view matrices are identity, the coordinate
; system has X=right, Y=up, and Z=behind you (negative Z goes into the screen).
;------------------------------------------------------------------------------
; r5 (forward) = normalized P
dp3 r1, $vPos, $vPos
rsq r5, r1
mul r5, r5, $vPos
mov r5.z, -r5.z ; This basis wants Z positive going into the screen
; so flip it here.
; r1 (up) = r5 x c24
mul r1, r5.xzyw, $SHADER_SPECIFIC_CONST_0; (This effectively does a cross product with [1,0,0,0]
; You wind up with [0, r5.z, -r5.y, 1]
dp3 r2, r1, r1
rsq r2, r2
mul r1, r1, r2
; r2 (right) = r1 x r5
mul r2, r1.yzxw, r5.zxyw
mad r2, -r1.zxyw, r5.yzxw, r2
sub r3, c[45 + a0.x], $vPos ; r3 = L - P
; transposed matrix mul
mul r0, r2, r3.xxxx ; x * right
mad r0, r1, r3.yyyy, r0 ; + y * up
mad r0, r5, r3.zzzz, r0 ; + z * forward
;------------------------------------------------------------------------------
; Put ||L - P|| into t1
;------------------------------------------------------------------------------
dp3 r2, r0, r0 ; r2 = Length(L - P)^2
rsq r3, r2 ; r3 = 1 / Length(L - P)
mul r8, r0, r3 ; r8 = Normalize(L - P)
mul r9, r8, $cQuarter ; r9 = Normalize(L - P) * 0.25
add oT1, r9, c0.w ; oT1 = Normalize(L - P) * 0.25 + 0.5
;------------------------------------------------------------------------------
; Setup the diffuse light color (C * r / ||L - P||^2)
;------------------------------------------------------------------------------
mul r8, c[46 + a0.x], $vSpecular ; r8 = C * r
rcp r7, r2 ; r7 = 1 / Length(L - P)^2
; rescale the color if necessary
mul r8, r8, r7 ; r8 = C * r / Length(L - P)^2
; We're doing both parts of an if statement here, with each part scaled by 0 or 1.
mul r9, r7, c[46 + a0.x] ; r9 = r / Length(L - P)^2
; If the light intensity scales the color > 1
sge r10, r9.xxxx, $cOne ; r10.x = 1 if the color's max component > 1
rcp r6, r9.xxxx
mul r6, r6, r10.xxxx ; r6 = 1 / max_component or [0,0,0,0] if max_component < 1
mul r2, r8, r6 ; rescaled color (all zeros if no component was > 1)
; else
slt r11, r9.xxxx, $cOne ; r11.x = 1 if the color's max component < 1
mad oD0.xyz, r8, r11, r2 ; if it was rescaled, then r8*r11 = 0
; if not, then r8*r11 = the original color
mov oD0.a, $vColor.a ; Pass in vertex alpha so the pixel shader can use it.