Improved error handling and error messages when love.graphics.newShader fails

src/modules/graphics/opengl/wrap_Graphics.cpp

@@ -508,14 +508,45 @@ int w_newShader(lua_State *L)
 	// clamp stack to 2 elements
 	lua_settop(L, 2);
 
+	// read any filepath arguments
+	for (int i = 1; i <= 2; i++)
+	{
+		if (!lua_isstring(L, i))
+			continue;
+
+		// call love.filesystem.isFile(arg_i)
+		luax_getfunction(L, "filesystem", "isFile");
+		lua_pushvalue(L, i);
+		lua_call(L, 1, 1);
+
+		bool isFile = luax_toboolean(L, -1);
+		lua_pop(L, 1);
+
+		if (isFile)
+		{
+			luax_getfunction(L, "filesystem", "read");
+			lua_pushvalue(L, i);
+			lua_call(L, 1, 1);
+			lua_replace(L, i);
+		}
+	}
+
+	bool has_arg1 = lua_isstring(L, 1);
+	bool has_arg2 = lua_isstring(L, 2);
+
+	// require at least one string argument
+	if (!(has_arg1 || has_arg2))
+		luaL_checkstring(L, 1);
+
 	luax_getfunction(L, "graphics", "_shaderCodeToGLSL");
 
-	// push vertexcode and pixelcode strings to the top of the stack so they become arguments for the function
+	// push vertexcode and pixelcode strings to the top of the stack
 	lua_pushvalue(L, 1);
 	lua_pushvalue(L, 2);
 
 	// call effectCodeToGLSL, returned values will be at the top of the stack
-	lua_pcall(L, 2, 2, 0);
+	if (lua_pcall(L, 2, 2, 0) != 0)
+		return luaL_error(L, "%s", lua_tostring(L, -1));
 
 	Shader::ShaderSources sources;
 
@@ -525,6 +556,8 @@ int w_newShader(lua_State *L)
 		std::string vertexcode(luaL_checkstring(L, -2));
 		sources[Shader::TYPE_VERTEX] = vertexcode;
 	}
+	else if (has_arg1 && has_arg2)
+		return luaL_error(L, "Could not parse vertex shader code (missing 'position' function?)");
 
 	// pixel shader code
 	if (lua_isstring(L, -1))
@@ -532,6 +565,8 @@ int w_newShader(lua_State *L)
 		std::string pixelcode(luaL_checkstring(L, -1));
 		sources[Shader::TYPE_PIXEL] = pixelcode;
 	}
+	else if (has_arg1 && has_arg2)
+		return luaL_error(L, "Could not parse pixel shader code (missing 'effect' function?)");
 
 	if (sources.empty())
 	{
@@ -539,7 +574,7 @@ int w_newShader(lua_State *L)
 		for (int i = 1; i <= 2; i++)
 		{
 			if (lua_isstring(L, i))
-				return luaL_argerror(L, i, "invalid or incomplete shader code");
+				return luaL_argerror(L, i, "missing 'position' or 'effect' function?");
 		}
 	}
 

src/scripts/graphics.lua

@@ -1361,9 +1361,11 @@ void main() {
 	end
 
 	function love.graphics._shaderCodeToGLSL(vertexcode, pixelcode)
+		local vertexarg, pixelarg = vertexcode, pixelcode
+
 		if vertexcode then
 			local s = vertexcode:gsub("\r\n\t", " ")
-			s = s:gsub("%w+(%s+)%(", "")
+			s = s:gsub("(%w+)(%s+)%(", "%1(")
 			if s:match("vec4%s*effect%(") then
 				pixelcode = vertexcode -- first argument contains pixel shader code
 			end
@@ -1371,9 +1373,10 @@ void main() {
 				vertexcode = nil -- first argument doesn't contain vertex shader code
 			end
 		end
+
 		if pixelcode then
 			local s = pixelcode:gsub("\r\n\t", " ")
-			s = s:gsub("%w+(%s+)%(", "")
+			s = s:gsub("(%w+)(%s+)%(", "%1(")
 			if s:match("vec4%s*position%(") then
 				vertexcode = pixelcode -- second argument contains vertex shader code
 			end
@@ -1385,6 +1388,7 @@ void main() {
 		if vertexcode then
 			vertexcode = createVertexCode(vertexcode)
 		end
+
 		if pixelcode then
 			pixelcode = createPixelCode(pixelcode)
 		end
@@ -1464,19 +1468,9 @@ void main() {
 
 	local newShader = love.graphics.newShader
 	function love.graphics.newShader(vertexcode, pixelcode)
-		love.graphics.newShader = function(vertexcode, pixelcode)
-			if love.filesystem then
-				if vertexcode and love.filesystem.exists(vertexcode) then
-					vertexcode = love.filesystem.read(vertexcode)
-				end
-				if pixelcode and love.filesystem.exists(pixelcode) then
-					pixelcode = love.filesystem.read(pixelcode)
-				end
-			end
-			return newShader(vertexcode, pixelcode)
-		end
+		love.graphics.newShader = newShader
 
-		local shader = love.graphics.newShader(vertexcode, pixelcode)
+		local shader = newShader(vertexcode, pixelcode)
 		local meta = getmetatable(shader)
 		meta.send = shader_dispatch_send
 		meta.sendBoolean = meta.sendFloat

src/scripts/graphics.lua.h

@@ -6388,13 +6388,16 @@ const unsigned char graphics_lua[] =
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@@ -6418,8 +6421,8 @@ const unsigned char graphics_lua[] =
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@@ -6626,36 +6629,11 @@ const unsigned char graphics_lua[] =
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