OpenSpace/modules/globebrowsing/meshes/grid.h

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2017                                                               *
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#ifndef __OPENSPACE_MODULE_GLOBEBROWSING___GRIDGEOMETRY___H__
#define __OPENSPACE_MODULE_GLOBEBROWSING___GRIDGEOMETRY___H__

#include <modules/globebrowsing/meshes/trianglesoup.h>

#include <ghoul/glm.h>

#include <memory>
#include <vector>

namespace openspace {
namespace globebrowsing {

/**
 * Abstract class defining an interface used for geometries with grid structures.
 * The class <code>Grid</code> should be extended for use of geometries with a 2D
 * structure where the number of segments in x and y direction represents the number
 * of vertices + 1 in each direction.
 */
class Grid {
public:
    Grid(int xSegments, int ySegments);
    
    virtual ~Grid() = default;

    TriangleSoup& geometry();

    /**
     * Returns the number of grid cells in the x direction. Hence the number of vertices
     * in the x direction is xResolution + 1.
     */
    virtual int xSegments() const = 0;
    
    /**
     * Returns the number of grid cells in the y direction. Hence the number of vertices
     * in the y direction is xResolution + 1.
     */
    virtual int ySegments() const = 0;

protected:
    /**
     * Should return the indices of vertices for a grid with size <code>xSegments</code> * 
     * <code>ySegments</code>. Where the number of vertices in each direction is the number
     * of segments + 1.
     */
    virtual std::vector<GLuint> createElements(int xSegments, int ySegments) = 0;
    
    /**
     * Should return the positions of vertices for a grid with size <code>xSegments</code>
     * * <code>ySegments</code>. Where the number of vertices in each direction is the
     * number of segments + 1.
     */
    virtual std::vector<glm::vec4> createPositions(int xSegments, int ySegments) = 0;
    
    /**
     * Should return the texture coordinates of vertices for a grid with size
     * <code>xSegments</code> * <code>ySegments</code>. Where the number of vertices in
     * each direction is the number of segments + 1.
     */
    virtual std::vector<glm::vec2>
        createTextureCoordinates(int xSegments, int ySegments) = 0;
    
    /**
     * Should return the normals of vertices for a grid with size <code>xSegments</code> *
     * <code>ySegments</code>. Where the number of vertices in each direction is the number
     * of segments + 1.
     */
    virtual std::vector<glm::vec3> createNormals(int xSegments, int ySegments) = 0;

    std::unique_ptr<TriangleSoup> _geometry;

    const int _xSegments;
    const int _ySegments;
};

} // namespace globebrowsing
} // namespace openspace

#endif // __OPENSPACE_MODULE_GLOBEBROWSING___GRIDGEOMETRY___H__