CloudViewer: refactoring + added CloudViewerCellPicker class to ignore picking backfaces (when backface culling is on)

guilib/include/rtabmap/gui/CloudViewerCellPicker.h

@@ -0,0 +1,40 @@
+/*
+ * CloudViewerCellPicker.h
+ *
+ *  Created on: Aug 21, 2018
+ *      Author: mathieu
+ */
+
+#ifndef GUILIB_SRC_CLOUDVIEWERCELLPICKER_H_
+#define GUILIB_SRC_CLOUDVIEWERCELLPICKER_H_
+
+#include "rtabmap/gui/RtabmapGuiExp.h" // DLL export/import defines
+
+#include <vtkCellPicker.h>
+
+namespace rtabmap {
+
+class RTABMAPGUI_EXP CloudViewerCellPicker : public vtkCellPicker {
+public:
+public:
+    static CloudViewerCellPicker *New ();
+	CloudViewerCellPicker();
+	virtual ~CloudViewerCellPicker();
+
+protected:
+	// overrided to ignore back faces
+    virtual double IntersectActorWithLine(const double p1[3],
+    		const double p2[3],
+			double t1, double t2,
+			double tol,
+			vtkProp3D *prop,
+			vtkMapper *mapper);
+
+private:
+	vtkGenericCell * cell_; //used to accelerate picking
+	vtkIdList * pointIds_; // used to accelerate picking
+};
+
+} /* namespace rtabmap */
+
+#endif /* GUILIB_SRC_CLOUDVIEWERCELLPICKER_H_ */