Merge pull request #657 from sebholt/display

Add new command line option: -display

Author: Lgt2x

USAGE.md

@@ -87,6 +87,7 @@ Here brief usage of command line options, supported by game.
 | Option               | Type    | Default                             | Platform | Description                                                       |
 |----------------------|---------|-------------------------------------|----------|-------------------------------------------------------------------|
 | `-dedicated`, `-d`   | boolean | Off                                 | all      | Run game in dedicated mode                                        |
+| `-display`           | integer | 0                                   | all      | Run game on the selected display                                  |
 | `-fullscreen`, `-f`  | boolean | On                                  | all      | Run game in fullscreen mode                                       |
 | `-logfile`           | boolean | Off                                 | all      | Enable file logging to Descent3.log                               |
 | `-loglevel <LEVEL>`  | string  | INFO (on Release), DEBUG (on Debug) | all      | Set log level (NONE, VERBOSE, DEBUG, INFO, WARNING, ERROR, FATAL) |

renderer/HardwareOpenGL.cpp

@@ -424,7 +424,21 @@ int opengl_Setup(oeApplication *app, const int *width, const int *height) {
   }
 
   if (!GSDLWindow) {
-    GSDLWindow = SDL_CreateWindow("Descent 3", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, winw, winh, flags);
+    int display = 0;
+    if (int display_arg = FindArg("-display"); display_arg != 0) {
+      if (const char * arg_index_str = GetArg (display_arg + 1); arg_index_str == nullptr) {
+        LOG_WARNING << "No parameter for -display given";
+      } else {
+        int arg_index = atoi(arg_index_str);
+        int display_count = SDL_GetNumVideoDisplays();
+        if ((arg_index < 0) || (arg_index >= display_count)) {
+          LOG_WARNING.printf( "Parameter for -display must be in the range 0..%i", display_count-1 );
+        } else {
+          display = arg_index;
+        }
+      }
+    }
+    GSDLWindow = SDL_CreateWindow("Descent 3", SDL_WINDOWPOS_UNDEFINED_DISPLAY(display), SDL_WINDOWPOS_UNDEFINED_DISPLAY(display), winw, winh, flags);
     if (!GSDLWindow) {
       LOG_ERROR.printf("OpenGL: SDL window creation failed: %s", SDL_GetError());
       return 0;