add VKBASALT_CONFIG support

README.md

@@ -91,6 +91,10 @@ The config file will be searched for in the following locations:
 
 If you want to make changes for one game only, you can create a file named `vkBasalt.conf` in the working directory of the game and change the values there.
 
+#### Quick override
+To override some of the default config options the `VKBASALT_CONFIG` env var can be used, e.g. `VKBASALT_CONFIG='effects=fxaa:cas;casSharpness=1.0'`.
+The separator is `;`
+
 #### Reshade Fx shaders
 
 To run reshade fx shaders e.g. shaders from the [reshade repo](https://github.com/crosire/reshade-shaders), you have to set `reshadeTexturePath` and `reshadeIncludePath` to the matching dirctories from the repo. To then use a specific shader you need to set a custom effect name to the shader path and then add that effect name to `effects` like every other effect.

src/config.cpp

@@ -12,6 +12,10 @@ namespace vkBasalt
         const char* tmpConfEnv       = std::getenv("VKBASALT_CONFIG_FILE");
         std::string customConfigFile = tmpConfEnv ? std::string(tmpConfEnv) : "";
 
+        // Custom config string
+        const char* tmpConfStringEnv   = std::getenv("VKBASALT_CONFIG");
+        std::string customConfigString = tmpConfStringEnv ? std::string(tmpConfStringEnv) : "";
+
         // User config file path
         const char* tmpHomeEnv     = std::getenv("XDG_DATA_HOME");
         std::string userConfigFile = tmpHomeEnv ? std::string(tmpHomeEnv) + "/vkBasalt/vkBasalt.conf"
@@ -32,18 +36,29 @@ namespace vkBasalt
             std::string(DATADIR) + "/vkBasalt/vkBasalt.conf",    // legacy system-wide config
         };
 
+        auto hasConfigFile = false;
         for (const auto& cFile : configPath)
         {
             std::ifstream configFile(cFile);
             if (!configFile.good())
                 continue;
 
             Logger::info("config file: " + cFile);
+            hasConfigFile = true;
             readConfigFile(configFile);
-            return;
+            break;
+        }
+
+        if (!hasConfigFile)
+        {
+            Logger::err("no good config file");
         }
 
-        Logger::err("no good config file");
+        if (!customConfigString.empty())
+        {
+            Logger::info("config string: " + customConfigString);
+            readConfigFromEnv(customConfigString);
+        }
     }
 
     Config::Config(const Config& other)
@@ -61,6 +76,17 @@ namespace vkBasalt
         }
     }
 
+    void Config::readConfigFromEnv(std::string configLine)
+    {
+        std::string line;
+        std::stringstream stream(configLine);
+
+        while (std::getline(stream, line, ';'))
+        {
+            readConfigLine(line);
+        }
+    }
+
     void Config::readConfigLine(std::string line)
     {
         std::string key;

src/config.hpp

@@ -31,6 +31,7 @@ namespace vkBasalt
 
         void readConfigLine(std::string line);
         void readConfigFile(std::ifstream& stream);
+        void readConfigFromEnv(std::string configLine);
 
         void parseOption(const std::string& option, int32_t& result);
         void parseOption(const std::string& option, float& result);