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materialsystem/stdshaders/ParticleSphere.vsh

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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.
+
+