added more options to set the focal length

include/ACGL/Scene/GenericCamera.hh

@@ -288,15 +288,25 @@ class GenericCamera
         void setStateFromString( const std::string &_state );
 
         /// The focal length is coupled to the sensor size in real cameras. As this camera does not model a
-        /// sensor size, the focal length is given in pixels and is in relation to the viewports resolution.
+        /// sensor size in mm, the focal length is given in pixels and is in relation to the viewports resolution.
         /// This model is also used by bundler.
         /// Note that this gives only useful results if the viewports aspect ratio is the same as the
         /// projections aspect ratio!
-        float getFocalLenght();
+        float getFocalLenghtInPixel() const;
 
         /// Sets the focal length in pixel relative to the viewport dimension. This will change the FoV.
-        /// See getFocalLenght() for more information.
-        void setFocalLength( float _focalLengthInPixel );
+        /// See getFocalLenghtInPixel() for more information.
+        void setFocalLengthInPixel( float _focalLengthInPixel );
+
+        /// The focal length is coupled to the sensor size in real cameras. As this camera does not model a
+        /// sensor size in mm (yet), a 135 (35mm) film size is assumed (framesize of 36*24mm).
+        /// The assumed sensor size might change in case other formats get supported later on but
+        /// 24mm height should be the default.
+        float getFocalLenghtInMM() const;
+
+        /// Sets the focal length in mm assuming a 135 film. This will change the FoV.
+        /// See getFocalLenghtInMM() for more information.
+        void setFocalLengthInMM( float _focalLengthInMM );
 
 	private:
 		/// the Matrix with the camera position/orientation.

src/ACGL/Scene/GenericCamera.cc

@@ -485,14 +485,27 @@ void GenericCamera::setStateFromString( const std::string &_state )
     mViewportSize      = toUvec2( token[pos++] );
 }
 
-float GenericCamera::getFocalLenght()
+float GenericCamera::getFocalLenghtInPixel() const
 {
-    return ( (float) mViewportSize.y ) / ( 2.0f * tan( calcDegToRad(0.5f * mHorizontalFieldOfView) ) );
+    return ( (float) mViewportSize.x ) / ( 2.0f * tan( calcDegToRad(0.5f * mHorizontalFieldOfView) ) );
 }
 
-void GenericCamera::setFocalLength( float _focalLengthInPixel )
+void GenericCamera::setFocalLengthInPixel( float _focalLengthInPixel )
 {
-    float hFoVrad = 2.0f * atan( ( 0.5f * mViewportSize.y ) * (1.0f / _focalLengthInPixel ) );
+    float hFoVrad = 2.0f * atan( ( 0.5f * mViewportSize.x ) * (1.0f / _focalLengthInPixel ) );
+    setHorizontalFieldOfView( calcRadToDeg( hFoVrad ) );
+}
+
+float GenericCamera::getFocalLenghtInMM() const
+{
+    glm::vec2 sensorSize = glm::vec2( 36.0f/mAspectRatio, 24.0f ); // in mm
+    return ( sensorSize.x ) / ( 2.0f * tan( calcDegToRad(0.5f * mHorizontalFieldOfView) ) );
+}
+
+void GenericCamera::setFocalLengthInMM( float _focalLengthInMM )
+{
+    glm::vec2 sensorSize = glm::vec2( 36.0f/mAspectRatio, 24.0f ); // in mm
+    float hFoVrad = 2.0f * atan( ( 0.5f * sensorSize.x ) * (1.0f / _focalLengthInMM ) );
     setHorizontalFieldOfView( calcRadToDeg( hFoVrad ) );
 }