Osgearth north arrow display

osgEarth The north arrow shows

This article shows a osgEarth How to display the north arrow in the environment . adopt osgEarth Self contained ImageControl Control displays the north arrow in the form of a picture , Simultaneous utilization osgGA::GUIEventHandler To realize the north arrow and osgEarth Ball interaction .

This article mainly solves the following problems ：

1. osgEarth Load image layer
2. osgEarth The display of the north arrow
3. The interaction between the north arrow and the ball

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Catalog

• 1 Preface
• 2 osgEarth The display of the north arrow
• 3 The interaction between the north arrow and the ball

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Content

• 1 Preface

osgEarth It's based on the 3D engine osg Development of 3D digital earth engine library , It supports loading common grid data （ Images and DEM）, Big data needs to build pyramids , At the same time, it is set as the geographic coordinate system , To achieve high loading efficiency, we need to process the image into tiles for storage .osgEarth Provides a wealth of Control Control , It is inherited from Camera class , It can be displayed on the interface , Realize the control function .

• 2 osgEarth The display of the north arrow

First load imageLayer,osgEarth configurable xml Format earth file , Use its data reading entry readNodeFile function , take earth Read the file as MapNode, So as to realize the loading of various layers , Of course earth The file contains the corresponding layers ,earth Document adoption xml The format organization of , You can use a text editor to display and edit , The sample code is as follows ：