Feature/geojson (#2595)

Add the option to add geojson components to globes, from geojson files. One geojson file creates one GeoJsonComponent, which in turn may contain multiple GlobeGeometryFeatures

Geojson is a format that supports points, lines, and polygons. In addition to the basic functionality, extra features have been added that will long-term allow rendering the geometry needed to represent KML files (another format for geospatial geometry data). Here are links to references for both formats:

    Geojson: https://geojson.org/
    KML: https://developers.google.com/kml/documentation/kmlreference

data/assets/examples/geojson includes some example files that I have used for testing. Any geojson file can also be added through drag-n-drop. Note however that you might need to change the AltitudeMode or HeightOffset properties for the feature to be visible.

include/openspace/rendering/fadeable.h

@@ -32,7 +32,7 @@ namespace openspace {
 /**
  * This class is an interface for all things fadeable in the software; things that need
  * a fade and opacity property, which will be combined into a final opacity value
- * 
+ *
  * A Fadeable can also be dependent on the fade value from a specified parent fadeable,
  * so that it fades out together with the parent
  */

include/openspace/rendering/helper.h

@@ -32,6 +32,11 @@ namespace ghoul::opengl {
     class Texture;
 } // namespace ghoul::opengl
 
+namespace openspace {
+    class LightSource;
+    struct RenderData;
+} // namespace openspace
+
 namespace openspace::rendering::helper {
 
 enum class Anchor {
@@ -109,6 +114,11 @@ struct VertexXYZ {
     GLfloat xyz[3];
 };
 
+struct VertexXYZNormal {
+    GLfloat xyz[3];
+    GLfloat normal[3];
+};
+
 VertexXYZ convertToXYZ(const Vertex& v);
 
 std::vector<VertexXYZ> convert(std::vector<Vertex> v);
@@ -119,6 +129,20 @@ std::vector<Vertex> createRing(int nSegments, float radius,
 std::pair<std::vector<Vertex>, std::vector<GLushort>>
 createSphere(int nSegments, glm::vec3 radii, glm::vec4 colors = glm::vec4(1.f));
 
+/**
+ * Data structure that can be used for rendering using multiple light directions
+ */
+struct LightSourceRenderData {
+    unsigned int nLightSources = 0;
+
+    // Buffers for uniform uploading
+    std::vector<float> intensitiesBuffer;
+    std::vector<glm::vec3> directionsViewSpaceBuffer;
+
+    void updateBasedOnLightSources(const RenderData& renderData,
+        const std::vector<std::unique_ptr<LightSource>>& sources);
+};
+
 } // namespace openspace::rendering::helper
 
 #endif // __OPENSPACE_CORE___HELPER___H__