From 1411e1f73a7fe682b833f58876daac2b25b3994a Mon Sep 17 00:00:00 2001
From: Maciej Suminski <maciej.suminski@cern.ch>
Date: Fri, 3 Aug 2018 10:22:34 +0200
Subject: [PATCH] GAL: added methods to modify rotation in the transformation
 matrix

---
 common/gal/graphics_abstraction_layer.cpp | 10 ++++++----
 include/gal/graphics_abstraction_layer.h  | 23 ++++++++++++++++++++++-
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/common/gal/graphics_abstraction_layer.cpp b/common/gal/graphics_abstraction_layer.cpp
index aa945d3bfd..15c5e4c404 100644
--- a/common/gal/graphics_abstraction_layer.cpp
+++ b/common/gal/graphics_abstraction_layer.cpp
@@ -48,6 +48,7 @@ GAL::GAL( GAL_DISPLAY_OPTIONS& aDisplayOptions ) :
     SetStrokeColor( COLOR4D( 1.0, 1.0, 1.0, 1.0 ) );
     SetLookAtPoint( VECTOR2D( 0, 0 ) );
     SetZoomFactor( 1.0 );
+    SetRotation( 0.0 );
     SetWorldUnitLength( 1.0 / METRIC_UNIT_LENGTH * 2.54 );   // 1 inch in nanometers
     SetScreenDPI( 106 );                                     // Display resolution setting
     SetDepthRange( VECTOR2D( GAL::MIN_DEPTH, GAL::MAX_DEPTH ) );
@@ -178,18 +179,19 @@ void GAL::ComputeWorldScreenMatrix()
 {
     computeWorldScale();
 
-    worldScreenMatrix.SetIdentity();
-
     MATRIX3x3D translation;
     translation.SetIdentity();
     translation.SetTranslation( 0.5 * VECTOR2D( screenSize ) );
 
+    MATRIX3x3D rotate;
+    rotate.SetIdentity();
+    rotate.SetRotation( rotation );
+
     MATRIX3x3D scale;
     scale.SetIdentity();
     scale.SetScale( VECTOR2D( worldScale, worldScale ) );
 
     MATRIX3x3D flip;
-
     flip.SetIdentity();
     flip.SetScale( VECTOR2D( globalFlipX ? -1.0 : 1.0, globalFlipY ? -1.0 : 1.0 ) );
 
@@ -197,7 +199,7 @@ void GAL::ComputeWorldScreenMatrix()
     lookat.SetIdentity();
     lookat.SetTranslation( -lookAtPoint );
 
-    worldScreenMatrix = translation * flip * scale * lookat * worldScreenMatrix;
+    worldScreenMatrix = translation * rotate * flip * scale * lookat;
     screenWorldMatrix = worldScreenMatrix.Inverse();
 }
 
diff --git a/include/gal/graphics_abstraction_layer.h b/include/gal/graphics_abstraction_layer.h
index ddecf6b470..713c42e581 100644
--- a/include/gal/graphics_abstraction_layer.h
+++ b/include/gal/graphics_abstraction_layer.h
@@ -506,7 +506,7 @@ public:
     /**
      * @brief Transform the context.
      *
-     * @param aTransformation is the ransformation matrix.
+     * @param aTransformation is the transformation matrix.
      */
     virtual void Transform( const MATRIX3x3D& aTransformation ) {};
 
@@ -695,6 +695,26 @@ public:
         return zoomFactor;
     }
 
+    /**
+     * @brief Set the rotation angle.
+     *
+     * @param aRotation is the new rotation angle (radians).
+     */
+    void SetRotation( double aRotation )
+    {
+        rotation = aRotation;
+    }
+
+    /**
+     * Get the rotation angle.
+     *
+     * @return The rotation angle (radians).
+     */
+    double GetRotation() const
+    {
+        return rotation;
+    }
+
     /**
      * @brief Set the range of the layer depth.
      *
@@ -1009,6 +1029,7 @@ protected:
     VECTOR2D           lookAtPoint;            ///< Point to be looked at in world space
 
     double             zoomFactor;             ///< The zoom factor
+    double             rotation;               ///< Rotation transformation (radians)
     MATRIX3x3D         worldScreenMatrix;      ///< World transformation
     MATRIX3x3D         screenWorldMatrix;      ///< Screen transformation
     double             worldScale;             ///< The scale factor world->screen