Make R_RemapShader multiple registration-aware

Make R_RemapShader handle shader registration flags correctly. For each
version of the shader, register the replacement shader with a matching
set of flags, instead of always using RSF_DEFAULT.

Also this fixes a bug that when the replacement shader was not found,
the 'defaulted' shader (one that was not found or failed parsing) for
rendering. New behavior is to not change the replacement state. Note
that Thunder has recently been relying on this bug - see
UnvanquishedAssets/map-thunder_src.dpkdir#7

Author: slipher

src/engine/renderer/tr_local.h

@@ -1163,6 +1163,8 @@ enum
 		int		autoSpriteMode;
 		bool autoSpriteWarned = false;
 
+		bool shaderRemapWarned;
+
 		uint8_t         numDeforms;
 		deformStage_t   deforms[ MAX_SHADER_DEFORMS ];
 
@@ -2999,7 +3001,6 @@ void GL_CompressedTexSubImage3D( GLenum target, GLint level, GLint xOffset, GLin
 
 	shader_t  *R_FindShader( const char *name, int flags );
 	shader_t  *R_GetShaderByHandle( qhandle_t hShader );
-	shader_t  *R_FindShaderByName( const char *name );
 	const char *RE_GetShaderNameFromHandle( qhandle_t shader );
 	void      R_InitShaders();
 	void      R_RemapShader( const char *oldShader, const char *newShader, const char *timeOffset );

src/engine/renderer/tr_shader.cpp

@@ -134,51 +134,35 @@ void R_RemapShader( const char *shaderName, const char *newShaderName, const cha
 {
 	char      strippedName[ MAX_QPATH ];
 	int       hash;
-	shader_t  *sh, *sh2;
-	qhandle_t h;
-
-	sh = R_FindShaderByName( shaderName );
-
-	if ( sh == nullptr || sh == tr.defaultShader )
-	{
-		h = RE_RegisterShader( shaderName, RSF_DEFAULT );
-		sh = R_GetShaderByHandle( h );
-	}
-
-	if ( sh == nullptr || sh == tr.defaultShader )
-	{
-		Log::Warn("R_RemapShader: shader %s not found", shaderName );
-		return;
-	}
-
-	sh2 = R_FindShaderByName( newShaderName );
-
-	if ( sh2 == nullptr || sh2 == tr.defaultShader )
-	{
-		h = RE_RegisterShader( newShaderName, RSF_DEFAULT );
-		sh2 = R_GetShaderByHandle( h );
-	}
-
-	if ( sh2 == nullptr || sh2 == tr.defaultShader )
-	{
-		Log::Warn("R_RemapShader: new shader %s not found", newShaderName );
-		return;
-	}
-
-	if ( sh->autoSpriteMode != sh2->autoSpriteMode ) {
-		Log::Warn("R_RemapShader: shaders %s and %s have different autoSprite modes", shaderName, newShaderName );
-		return;
-	}
 
 	// remap all the shaders with the given name
 	// even tho they might have different lightmaps
 	COM_StripExtension3( shaderName, strippedName, sizeof( strippedName ) );
 	hash = generateHashValue( strippedName, FILE_HASH_SIZE );
+	bool found = false;
 
-	for ( sh = shaderHashTable[ hash ]; sh; sh = sh->next )
+	for ( shader_t *sh = shaderHashTable[ hash ]; sh; sh = sh->next )
 	{
 		if ( Q_stricmp( sh->name, strippedName ) == 0 )
 		{
+			found = true;
+			shader_t *sh2 = R_FindShader( newShaderName, sh->registerFlags );
+
+			if ( sh2->defaultShader )
+			{
+				if ( !sh2->shaderRemapWarned )
+				{
+					Log::Warn( "R_RemapShader: new shader %s not found", newShaderName );
+					sh2->shaderRemapWarned = true;
+				}
+				return;
+			}
+
+			if ( sh->autoSpriteMode != sh2->autoSpriteMode ) {
+				Log::Warn( "R_RemapShader: shaders %s and %s have different autoSprite modes", shaderName, newShaderName );
+				return;
+			}
+
 			if ( sh != sh2 )
 			{
 				sh->remappedShader = sh2;
@@ -189,6 +173,17 @@ void R_RemapShader( const char *shaderName, const char *newShaderName, const cha
 			}
 		}
 	}
+
+	if ( !found )
+	{
+		// try registering it to detect typos
+		shader_t *test = R_FindShader( shaderName, RSF_DEFAULT );
+
+		if ( test->defaultShader )
+		{
+			Log::Warn( "R_RemapShader: shader %s not found", shaderName );
+		}
+	}
 }
 
 /*
@@ -5987,43 +5982,6 @@ static const char    *FindShaderInShaderText( const char *shaderName )
 	return nullptr;
 }
 
-/*
-==================
-R_FindShaderByName
-
-Will always return a valid shader, but it might be the
-default shader if the real one can't be found.
-==================
-*/
-shader_t       *R_FindShaderByName( const char *name )
-{
-	char     strippedName[ MAX_QPATH ];
-	int      hash;
-	shader_t *sh;
-
-	if ( ( name == nullptr ) || ( name[ 0 ] == 0 ) )
-	{
-		// bk001205
-		return tr.defaultShader;
-	}
-
-	COM_StripExtension3( name, strippedName, sizeof( strippedName ) );
-
-	hash = generateHashValue( strippedName, FILE_HASH_SIZE );
-
-	// see if the shader is already loaded
-	for ( sh = shaderHashTable[ hash ]; sh; sh = sh->next )
-	{
-		if ( Q_stricmp( sh->name, strippedName ) == 0 )
-		{
-			// match found
-			return sh;
-		}
-	}
-
-	return tr.defaultShader;
-}
-
 static void ClearGlobalShader()
 {
 	ResetStruct( shader );