OPENGL: Fix aspect ratio correction behavior.

Now only 320x200 and 640x400 will result in aspect ratio correction to be used
if the user requested it. This should fix some strechting in Myst/Riven.

3 files changed, 18 insertions, 14 deletions

diff --git a/backends/graphics/opengl/opengl-graphics.cpp b/backends/graphics/opengl/opengl-graphics.cpp
index 57c2378649..40ef17e477 100644
--- a/backends/graphics/opengl/opengl-graphics.cpp
+++ b/backends/graphics/opengl/opengl-graphics.cpp
@@ -1245,12 +1245,16 @@ void OpenGLGraphicsManager::toggleAntialiasing() {
 	_transactionDetails.filterChanged = true;
 }
 
-uint OpenGLGraphicsManager::getAspectRatio() {
+uint OpenGLGraphicsManager::getAspectRatio() const {
 	// In case we enable aspect ratio correction we force a 4/3 ratio.
+	// But just for 320x200 and 640x400 games, since other games do not need
+	// this.
 	// TODO: This makes OpenGL Normal behave like OpenGL Conserve, when aspect
 	// ratio correction is enabled, but it's better than the previous 4/3 mode
 	// mess at least...
-	if (_videoMode.aspectRatioCorrection)
+	if (_videoMode.aspectRatioCorrection
+	    && ((_videoMode.screenWidth == 320 && _videoMode.screenHeight == 200)
+	    || (_videoMode.screenWidth == 640 && _videoMode.screenHeight == 400)))
 		return 13333;
 	else if (_videoMode.mode == OpenGL::GFX_NORMAL)
 		return _videoMode.hardwareWidth * 10000 / _videoMode.hardwareHeight;
diff --git a/backends/graphics/opengl/opengl-graphics.h b/backends/graphics/opengl/opengl-graphics.h
index 8a110b2d5f..42cfbacc85 100644
--- a/backends/graphics/opengl/opengl-graphics.h
+++ b/backends/graphics/opengl/opengl-graphics.h
@@ -214,10 +214,7 @@ protected:
 	virtual void calculateDisplaySize(int &width, int &height);
 	virtual void refreshDisplaySize();
 
-	/**
-	 * Returns the current target aspect ratio x 10000
-	 */
-	virtual uint getAspectRatio();
+	uint getAspectRatio() const;
 
 	bool _formatBGR;
 
diff --git a/backends/graphics/openglsdl/openglsdl-graphics.cpp b/backends/graphics/openglsdl/openglsdl-graphics.cpp
index d2810818e7..84515732fe 100644
--- a/backends/graphics/openglsdl/openglsdl-graphics.cpp
+++ b/backends/graphics/openglsdl/openglsdl-graphics.cpp
@@ -313,14 +313,17 @@ bool OpenGLSdlGraphicsManager::loadGFXMode() {
 		_videoMode.overlayWidth = _videoMode.hardwareWidth = _videoMode.screenWidth * scaleFactor;
 		_videoMode.overlayHeight = _videoMode.hardwareHeight = _videoMode.screenHeight * scaleFactor;
 
-		int screenAspectRatio = _videoMode.screenWidth * 10000 / _videoMode.screenHeight;
-		int desiredAspectRatio = getAspectRatio();
-
-		// Do not downscale dimensions, only enlarge them if needed
-		if (screenAspectRatio > desiredAspectRatio)
-			_videoMode.hardwareHeight = (_videoMode.overlayWidth * 10000  + 5000) / desiredAspectRatio;
-		else if (screenAspectRatio < desiredAspectRatio)
-			_videoMode.hardwareWidth = (_videoMode.overlayHeight * desiredAspectRatio + 5000) / 10000;
+		// The only modes where we need to adapt the aspect ratio are 320x200
+		// and 640x400. That is since our aspect ratio correction in fact is
+		// only used to ensure that the original pixel size aspect for these
+		// modes is used.
+		// (Non-square pixels on old monitors vs square pixel on new ones).
+		if (_videoMode.aspectRatioCorrection
+		    && ((_videoMode.screenWidth == 320 && _videoMode.screenHeight == 200)
+		    || (_videoMode.screenWidth == 640 && _videoMode.screenHeight == 400)))
+			_videoMode.overlayHeight = _videoMode.hardwareHeight = 240 * scaleFactor;
+		else
+			_videoMode.overlayHeight = _videoMode.hardwareHeight = _videoMode.screenHeight * scaleFactor;
 	}
 
 	_screenResized = false;