attempt to load extra textures the DarkPlaces way

Author: illwieckz

src/engine/renderer/tr_local.h

@@ -1076,6 +1076,11 @@ static inline void halfToFloat( const f16vec4_t in, vec4_t out )
 
 		bool        active;
 
+		// DarkPlaces compatibility
+		// only used to backup color map texture name
+		// to guess extra map name
+		char            textureName[ MAX_QPATH ];
+
 		textureBundle_t bundle[ MAX_TEXTURE_BUNDLES ];
 
 		expression_t    ifExp;
@@ -3150,6 +3155,7 @@ static inline void halfToFloat( const f16vec4_t in, vec4_t out )
 	void    R_InitImages();
 	void    R_ShutdownImages();
 
+	int R_FindAltImage( char *filename, const char **prefix );
 	image_t *R_FindImageFile( const char *name, int bits, filterType_t filterType, wrapType_t wrapType );
 	image_t *R_FindCubeImage( const char *name, int bits, filterType_t filterType, wrapType_t wrapType );
 

src/engine/renderer/tr_shader.cpp

@@ -1442,6 +1442,13 @@ static bool LoadMap( shaderStage_t *stage, const char *buffer )
 		return false;
 	}
 
+	// DarkPlaces compatibility
+	// a diffuse maps loaded without stage keyword is a color map
+	// backup texture name somewhere, its basename will be needed for extra map lookup
+	if ( stage->type == stageType_t::ST_COLORMAP ) {
+		strcpy( stage->textureName, buffer );
+	}
+
 	return true;
 }
 
@@ -3100,6 +3107,23 @@ static void ParseLightFalloffImage( shaderStage_t *stage, const char **text )
 	}
 }
 
+struct extraMapParser_t
+{
+	const char *suffix;
+	const char *description;
+	void ( *parser ) ( shaderStage_t*, const char** );
+};
+
+static const extraMapParser_t extraMapParsers[] =
+{
+	{ "_glow", "glow map", ParseGlowMap },
+	{ "_norm", "normal map", ParseNormalMap },
+	{ "_gloss", "specular map", ParseSpecularMap },
+	{ "_reflect", "reflection map", ParseReflectionMap },
+};
+
+static int numExtraMapParsers = ARRAY_LEN( extraMapParsers );
+
 /*
 =================
 ParseShader
@@ -3111,13 +3135,12 @@ will optimize it.
 */
 static bool ParseShader( const char *_text )
 {
+	int  s;
 	const char **text;
 	char *token;
-	int  s;
 
 	s = 0;
 	text = &_text;
-
 	token = COM_ParseExt2( text, true );
 
 	if ( token[ 0 ] != '{' )
@@ -3679,6 +3702,46 @@ static bool ParseShader( const char *_text )
 		}
 	}
 
+	// DarkPlaces compatibility
+	// It looks for extra maps based on their suffixes.
+	int c;
+	shaderStage_t colorMapStage;
+
+	for (c = 0; c < s; c++) {
+		if ( stages[c].type == stageType_t::ST_COLORMAP && stages[c].textureName != nullptr ) {
+			colorMapStage = stages[c];
+			break;
+		}
+	}
+
+	if ( colorMapStage.textureName[0] != '\0' )
+	{
+		const char *prefix; // not used but required by R_FindAltImage
+		const char *mapName;
+		char baseName[ MAX_QPATH ];
+
+		Log::Debug("looking for extra maps for color map: '%s'", colorMapStage.textureName );
+		COM_StripExtension3( colorMapStage.textureName, baseName, MAX_QPATH );
+
+		int i;
+		for ( i = 0; i < numExtraMapParsers; i++ )
+		{
+			if ( s >= ( MAX_SHADER_STAGES - 1 ) )
+			{
+				Log::Warn("too many stages in shader %s", shader.name );
+				return false;
+			}
+
+			mapName = va( "%s%s", baseName, extraMapParsers[i].suffix );
+			if( R_FindAltImage( (char*) mapName, &prefix ) >= 0 ) {
+				Log::Debug("found implicit %s '%s'", extraMapParsers[i].description, mapName );
+				// colorMapStage.type = stageType_t::ST_DIFFUSEMAP;
+				extraMapParsers[i].parser( &stages[ s ], &mapName );
+				s++;
+			}
+		}
+	}
+
 	// ignore shaders that don't have any stages, unless it is a sky or fog
 	if ( s == 0 && !shader.forceOpaque && !shader.isSky && !( shader.contentFlags & CONTENTS_FOG ) && implicitMap[ 0 ] == '\0' )
 	{