visualization_cross_section

The source file containing the main() function:

/********************************************************************
 * 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/>.
 ********************************************************************/
 
#include <easy3d/renderer/camera.h>
#include <easy3d/util/resource.h>
#include <easy3d/util/initializer.h>
#include <easy3d/util/timer.h>
 
#include "viewer.h"
 
 
using namespace easy3d;
 
int test_cross_section(int duration) {
    CrossSection viewer("CrossSection");
    viewer.camera()->setViewDirection(vec3(-1, 1, -1));
 
    const std::string file_name = resource::directory() + "/data/bunny.ply";
    if (!viewer.add_model(file_name)) {
        LOG(ERROR) << "failed to load model. Please make sure the file exists and format is correct.";
        return EXIT_FAILURE;
    }
 
    viewer.set_usage("testing cross section...");
 
    Timer<>::single_shot(duration, (Viewer*)&viewer, &Viewer::exit);
    return viewer.run();
}

The header file of the viewer class:

/********************************************************************
 * 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_TESTS_CROSS_SECTION_H
#define EASY3D_TESTS_CROSS_SECTION_H
 
#include <easy3d/viewer/viewer.h>
 
namespace easy3d {
 
    class CrossSection : public Viewer
    {
    public:
        explicit CrossSection(const std::string& title);
        ~CrossSection() override;
 
    protected:
        // manipulate the crosssection plane
        bool mouse_drag_event(int x, int y, int dx, int dy, int button, int modifiers) override;
 
        // draw the clipping plane
        void post_draw() override;
    };
 
}
 
#endif  // EASY3D_TESTS_CROSS_SECTION_H

The source file of the viewer class:

/********************************************************************
 * 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/>.
 ********************************************************************/
 
#include "viewer.h"
#include <easy3d/renderer/clipping_plane.h>
#include <easy3d/renderer/manipulated_frame.h>
#include <easy3d/renderer/manipulator.h>
 
 
namespace easy3d {
 
    CrossSection::CrossSection(const std::string &title) : Viewer(title) {
        // Code of interest:
        ClippingPlane::instance()->set_enabled(true);
    }
 
    CrossSection::~CrossSection() {
        // Disable it (otherwise it affects the visualization in subsequent tests)
        ClippingPlane::instance()->set_enabled(false);
    }
 
    void CrossSection::post_draw() {
        // Code of interest:
        ClippingPlane::instance()->draw(camera());
 
        Viewer::post_draw();
    }
 
    bool CrossSection::mouse_drag_event(int x, int y, int dx, int dy, int button, int modifiers) {
        ManipulatedFrame* frame = ClippingPlane::instance()->manipulator()->frame();
 
        if (pressed_button_ == BUTTON_LEFT)
            frame->action_rotate(x, y, dx, dy, camera_, ManipulatedFrame::NONE);
        else if (pressed_button_ == BUTTON_RIGHT)
            frame->action_translate(x, y, dx, dy, camera_, ManipulatedFrame::NONE);
        else
            return Viewer::mouse_drag_event(x, y, dx, dy, button, modifiers);
 
        return false;
    }
 
}