Solved MAC OpenGL scaling issue. Turns out it was related to the retina

screen having a 2x device to framebuffer scaling.

src/drivers/Qt/GameViewerGL.cpp

@@ -20,6 +20,7 @@ gameViewGL_t::gameViewGL_t(QWidget *parent)
 	use_sw_pix_remap = 0;
 	remap_pixBuf = NULL;
 	remap_pixPtr = NULL;
+	devPixRatio  = 1.0f;
 
 }
 
@@ -49,8 +50,9 @@ gameViewGL_t::~gameViewGL_t(void)
 	 }
 }
 
-int gameViewGL_t::init(void)
+int gameViewGL_t::init( double devPixRatioInput )
 {
+	devPixRatio = devPixRatioInput;
 	return 0;
 }
 
@@ -151,6 +153,8 @@ void gameViewGL_t::initializeGL(void)
 
 void gameViewGL_t::resizeGL(int w, int h)
 {
+	w = (int)( devPixRatio * w );
+	h = (int)( devPixRatio * h );
 	printf("GL Resize: %i x %i \n", w, h );
 	glViewport(0, 0, w, h);
 

src/drivers/Qt/GameViewerGL.h

@@ -14,7 +14,7 @@ class gameViewGL_t : public QOpenGLWidget, protected QOpenGLFunctions
 		gameViewGL_t(QWidget *parent = 0);
 	   ~gameViewGL_t(void);
 
-		int  init(void);
+		int  init( double devPixRatio = 1.0f );
 
 	protected:
     void initializeGL(void);
@@ -25,6 +25,7 @@ class gameViewGL_t : public QOpenGLWidget, protected QOpenGLFunctions
 	 void calcPixRemap(void);
 	 void doRemap(void);
 
+	 double devPixRatio;
 	 int  texture_width;
 	 int  texture_height;
 	 int  view_width;

src/drivers/Qt/keyscan.cpp

@@ -2,7 +2,7 @@
 //
 
 #include <QtCore>
-#include <SDL2/SDL.h>
+#include <SDL.h>
 
 #include "Qt/keyscan.h"
 

src/drivers/Qt/keyscan.h

@@ -45,7 +45,7 @@
 
 #include <QtCore>
 #include <QKeyEvent>
-#include <SDL2/SDL.h>
+#include <SDL.h>
 
 SDL_Keycode convQtKey2SDLKeyCode( Qt::Key q );
 

src/drivers/Qt/main.cpp

@@ -1,19 +1,29 @@
 #include <QApplication>
+#include <QScreen>
 
 #include "Qt/GameApp.h"
 #include "Qt/fceuWrapper.h"
 
 int main( int argc, char *argv[] )
 {
+	double devPixRatio = 1.0;
 	 QApplication app(argc, argv);
     gameWin_t win;
 
+    QScreen *screen = QGuiApplication::primaryScreen();
+
+    if ( screen != NULL )
+    {
+	devPixRatio = screen->devicePixelRatio();
+    	printf("Ratio: %f \n", screen->devicePixelRatio() );
+    }
+
 	 fceuWrapperInit( argc, argv );
 
-	 win.resize( 512, 512 );
+	 //win.resize( 512, 512 );
 	 win.show();
 
-	 win.viewport->init();
+	 win.viewport->init( devPixRatio );
 
     return app.exec();
 }