tr_image: add _null image

Author: illwieckz

src/engine/renderer/tr_image.cpp

@@ -2758,6 +2758,11 @@ void R_CreateBuiltinImages()
 
 	tr.blueImage = R_CreateImage( "_blue", ( const byte ** ) &dataPtr, 1, 1, 1, imageParams );
 
+	// null
+	memset( data, 0, sizeof( data ) );
+
+	tr.nullImage = R_CreateImage( "_null", ( const byte ** ) &dataPtr, 1, 1, 1, imageParams );
+
 	// generate a default normalmap with a fully opaque heightmap (no displacement)
 	Vector4Set( data, 128, 128, 255, 255 );
 

src/engine/renderer/tr_local.h

@@ -2447,6 +2447,7 @@ enum
 		image_t    *redImage;
 		image_t    *greenImage;
 		image_t    *blueImage;
+		image_t    *nullImage; // full of 0x0
 		image_t    *flatImage; // use this as default normalmap
 		image_t    *blackCubeImage;
 		image_t    *whiteCubeImage;

src/engine/renderer/tr_shader.cpp

@@ -1464,6 +1464,12 @@ static bool LoadMap( shaderStage_t *stage, const char *buffer, stageType_t type,
 		stage->bundle[ bundleIndex ].image[ 0 ] = tr.blueImage;
 		return true;
 	}
+	else if ( !Q_stricmp( token, "$nullimage" ) || !Q_stricmp( token, "$null" )
+		|| !Q_stricmp( token, "_null" ) || !Q_stricmp( token, "*null" ) )
+	{
+		stage->bundle[ bundleIndex ].image[ 0 ] = tr.nullImage;
+		return true;
+	}
 	else if ( !Q_stricmp( token, "$flatimage" ) || !Q_stricmp( token, "$flat" )
 		|| !Q_stricmp( token, "_flat" ) || !Q_stricmp( token, "*flat" ) )
 	{