- Add currentDrawBufferResolution method in WindowWrapper

- Base renderer resolution on draw buffer resolution instead of window res
- Obtain number of aa samples from config file, instead of hard coding to
  eight samples

include/openspace/engine/wrapper/sgctwindowwrapper.h

@@ -45,7 +45,9 @@ public:
     uint32_t mouseButtons(int maxNumber) const override;
     glm::ivec2 currentWindowSize() const override;
     glm::ivec2 currentWindowResolution() const override;
-    
+    glm::ivec2 currentDrawBufferResolution() const override;
+    int currentNumberOfAaSamples() const override;
+
     bool isRegularRendering() const override;
     
     glm::mat4 viewProjectionMatrix() const override;

include/openspace/engine/wrapper/windowwrapper.h

@@ -26,6 +26,7 @@
 #define __WINDOWWRAPPER_H__
 
 #include <ghoul/glm.h>
+#include <ghoul/misc/exception.h>
 
 #include <cstdint>
 #include <functional>
@@ -104,6 +105,18 @@ public:
     virtual glm::ivec2 currentWindowResolution() const;
     
     /**
+     * Returns the resolution of the currently active framebuffer in pixel coordinates.
+     * On default, this method returns the same size as #currentWindowSize.
+     * \return The resolution of the currently active window in pixel coordinates
+     */
+    virtual glm::ivec2 currentDrawBufferResolution() const;
+
+    /**
+     * Returns the number of anti-aliasing samples used in the current window.
+     */
+    virtual int currentNumberOfAaSamples() const;
+
+	/**
      * Returns <code>true</code> if the current rendering method is regular, i.e., it is
      * a flat projection without non-linear distortions. Returns <code>false</code> in
      * other cases, for example fisheye projections. On default, this method will return
@@ -163,6 +176,10 @@ public:
      * Advises the windowing system to take a screenshot. This method defaults to a no-op.
      */
     virtual void takeScreenshot() const;
+
+    struct WindowWrapperException : public ghoul::RuntimeError {
+        explicit WindowWrapperException(const std::string& msg);
+    };
 };
 
 } // namespace openspace

include/openspace/rendering/abufferrenderer.h

@@ -104,6 +104,7 @@ private:
 	GLuint _fragmentBuffer;
 	GLuint _fragmentTexture;
 	GLuint _vertexPositionBuffer;
+	int _nAaSamples;
 
     ghoul::Dictionary _rendererData;
 };		// ABufferRenderer