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materialsystem/stdshaders/shadow_dx6.cpp

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $Header: $
+// $NoKeywords: $
+//=============================================================================//
+
+#include "shaderlib/cshader.h"
+
+// memdbgon must be the last include file in a .cpp file!!!
+#include "tier0/memdbgon.h"
+
+DEFINE_FALLBACK_SHADER( Shadow, Shadow_DX6 )
+
+BEGIN_SHADER_FLAGS( Shadow_DX6, "Help for Shadow_DX6", SHADER_NOT_EDITABLE )
+
+	BEGIN_SHADER_PARAMS
+	END_SHADER_PARAMS
+
+	SHADER_INIT_PARAMS()
+	{
+		// FIXME: Need fallback for dx5, don't fade out shadows, just pop them out
+
+		/*
+		The alpha blending state either must be:
+
+	Src Color * Dst Color + Dst Color * 0	
+		(src color = C*A + 1-A)
+
+or
+
+  // Can't be this, doesn't work with fog
+	Src Color * Dst Color + Dst Color * (1-Src Alpha)	
+		(src color = C * A, Src Alpha = A)
+
+	*/
+	}
+
+	SHADER_INIT
+	{
+		if (params[BASETEXTURE]->IsDefined())
+			LoadTexture( BASETEXTURE );
+	}
+
+	SHADER_DRAW
+	{
+		SHADOW_STATE
+		{
+			pShaderShadow->EnableTexture( SHADER_SAMPLER0, true );
+			pShaderShadow->EnableTexture( SHADER_SAMPLER1, true );
+
+			// To accomplish shadow fading, subtract vertex alpha from texture alpha
+			// color channel isn't used...
+			pShaderShadow->EnableCustomPixelPipe( true );
+			pShaderShadow->CustomTextureStages( 2 );
+			pShaderShadow->CustomTextureOperation( SHADER_TEXTURE_STAGE0, 
+				SHADER_TEXCHANNEL_COLOR, SHADER_TEXOP_SELECTARG1, 
+				SHADER_TEXARG_TEXTURE, SHADER_TEXARG_VERTEXCOLOR );
+			pShaderShadow->CustomTextureOperation( SHADER_TEXTURE_STAGE0, 
+				SHADER_TEXCHANNEL_ALPHA, SHADER_TEXOP_SUBTRACT, 
+				SHADER_TEXARG_TEXTURE, SHADER_TEXARG_VERTEXCOLOR );
+
+			// Blend between white and the vertex color...
+			pShaderShadow->CustomTextureOperation( SHADER_TEXTURE_STAGE1, 
+				SHADER_TEXCHANNEL_COLOR, SHADER_TEXOP_BLEND_PREVIOUSSTAGEALPHA, 
+				SHADER_TEXARG_CONSTANTCOLOR, SHADER_TEXARG_TEXTURE );
+			pShaderShadow->CustomTextureOperation( SHADER_TEXTURE_STAGE1, 
+				SHADER_TEXCHANNEL_ALPHA, SHADER_TEXOP_SELECTARG1, 
+				SHADER_TEXARG_PREVIOUSSTAGE, SHADER_TEXARG_VERTEXCOLOR );
+
+			EnableAlphaBlending( SHADER_BLEND_DST_COLOR, SHADER_BLEND_ZERO );
+			pShaderShadow->DrawFlags( SHADER_DRAW_POSITION | SHADER_DRAW_COLOR | 
+				SHADER_DRAW_TEXCOORD0 | SHADER_DRAW_TEXCOORD1 );
+			// We need to fog to *white* regardless of overbrighting...
+			FogToWhite();
+		}
+		DYNAMIC_STATE
+		{
+			BindTexture( SHADER_SAMPLER0, BASETEXTURE, FRAME );
+			BindTexture( SHADER_SAMPLER1, BASETEXTURE, FRAME );
+			SetFixedFunctionTextureTransform( MATERIAL_TEXTURE0, BASETEXTURETRANSFORM );
+			SetFixedFunctionTextureTransform( MATERIAL_TEXTURE1, BASETEXTURETRANSFORM );
+
+			// The constant color is the shadow color...
+			SetColorState( COLOR );
+		}
+		Draw( );
+	}
+END_SHADER