picker.h

/********************************************************************
 * Copyright (C) 2015 Liangliang Nan <liangliang.nan@gmail.com>
 * https://3d.bk.tudelft.nl/liangliang/
 *
 * This file is part of Easy3D. If it is useful in your research/work,
 * I would be grateful if you show your appreciation by citing it:
 * ------------------------------------------------------------------
 *      Liangliang Nan.
 *      Easy3D: a lightweight, easy-to-use, and efficient C++ library
 *      for processing and rendering 3D data.
 *      Journal of Open Source Software, 6(64), 3255, 2021.
 * ------------------------------------------------------------------
 *
 * Easy3D is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License Version 3
 * as published by the Free Software Foundation.
 *
 * Easy3D is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 ********************************************************************/
 
#ifndef EASY3D_GUI_PICKER_H
#define EASY3D_GUI_PICKER_H
 
#include <easy3d/core/types.h>
#include <easy3d/renderer/camera.h>
 
 
namespace easy3d {
 
    class FramebufferObject;

    class Picker {
    public:
        explicit Picker(const Camera *cam);
        virtual ~Picker();

        const Camera *camera() const { return camera_; }

        Line3 picking_line(int x, int y) const {
            const vec3 p_near = unproject(x, y, 0);
            const vec3 p_far = unproject(x, y, 1);
            return Line3::from_two_points(p_near, p_far);
        }

        vec3 picking_dir(int x, int y) const {
            return picking_line(x, y).direction();
        }

        vec3 project(const vec3 &p) const {
            return camera()->projectedCoordinatesOf(p);
        }

        vec3 unproject(int x, int y, float depth) const {
            return camera()->unprojectedCoordinatesOf(vec3(static_cast<float>(x), static_cast<float>(y), depth));
        }

        void screen_to_opengl(int x, int y, int &gl_x, int &gl_y, int width, int height) const;
 
    protected:
        void setup_framebuffer(int width, int height);
 
    protected:
        const Camera *camera_;
 
        bool use_gpu_if_supported_; // use GPU if supported
 
        // All the picking tasks can share the same framebuffer
        static FramebufferObject *fbo_;
    };
 
}
 
#endif  // EASY3D_GUI_PICKER_H