//
// Stars.h
// interface
//
// Created by Tobias Schwinger on 3/22/13.
// Copyright (c) 2013 High Fidelity, Inc. All rights reserved.
//

#ifndef __interface__Stars__
#define __interface__Stars__

#include <glm/glm.hpp>

namespace starfield { class Controller; }

// 
// Starfield rendering component.
// 
class Stars  {

        starfield::Controller* _ptrController;

    public:

        Stars();
        ~Stars();

        // 
        // Reads input file from URL. Returns true upon success.
        //
        // The limit parameter allows to reduce the number of stars
        // that are loaded, keeping the brightest ones.
        // 
        bool readInput(const char* url, const char* cacheFile = 0l, unsigned limit = 200000);

        // 
        // Renders the starfield from a local viewer's perspective.
        // The parameters specifiy the field of view.
        // 
        void render(float fovY, float aspect, float nearZ);

        // 
        // Sets the resolution for FOV culling.
        //
        // The parameter determines the number of tiles in azimuthal 
        // and altitudinal directions. 
        //
        // GPU resources are updated upon change in which case 'true'
        // is returned.
        // 
        bool setResolution(unsigned k);

        // 
        // Allows to alter the number of stars to be rendered given a
        // factor. The least brightest ones are omitted first.
        //
        // The further parameters determine when GPU resources should
        // be reallocated. Its value is fractional in respect to the
        // last number of stars 'n' that caused 'n * (1+overalloc)' to
        // be allocated. When the next call to setLOD causes the total
        // number of stars that could be rendered to drop below 'n * 
        // (1-realloc)' or rises above 'n * (1+realloc)' GPU resources
        // are updated. Note that all parameters must be fractions,
        // that is within the range [0;1] and that 'overalloc' must be
        // greater than or equal to 'realloc'.
        //
        // The current level of detail is returned as a float in [0;1].
        // 
        float changeLOD(float factor,
                        float overalloc = 0.25, float realloc = 0.15);

    private:
        // don't copy/assign
        Stars(Stars const&); // = delete;
        Stars& operator=(Stars const&); // delete;
};


#endif