Tutorial_206_CameraInterpolation

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 "viewer.h"
#include <easy3d/util/resource.h>
#include <easy3d/util/initializer.h>
 
 
// This example shows how to
//        - creat an exploration path using the key frame interpolator,
//        - play the path as an animation.
 
using namespace easy3d;
 
int main(int argc, char** argv) {
    // initialize Easy3D.
    initialize();
 
    const std::string& file_name = resource::directory() + "/data/sphere.obj";
 
    CameraInterpolation viewer(EXAMPLE_TITLE);
    if (!viewer.add_model(file_name, true)) {
        LOG(ERROR) << "failed to load model. Please make sure the file exists and format is correct.";
        return EXIT_FAILURE;
    }
 
    return viewer.run();
}

The header file of the 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_TUTORIAL_CAMERA_INTERPOLATION_H
#define EASY3D_TUTORIAL_CAMERA_INTERPOLATION_H
 
#include <easy3d/viewer/viewer.h>
 
 
namespace easy3d {
    class KeyFrameInterpolator;
}
 
// This tutorial shows how to interpolate camera frames to
// animate model exploration.
 
class CameraInterpolation : public easy3d::Viewer
{
public:
    explicit CameraInterpolation(const std::string& title);
    ~CameraInterpolation() override;
    
protected:
    bool key_press_event(int key, int modifiers) override;
    void draw() const override;
 
private:
    easy3d::KeyFrameInterpolator* interpolator_;
};
 
 
#endif // EASY3D_TUTORIAL_CAMERA_INTERPOLATION_H

The source file of the 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/camera.h>
#include <easy3d/renderer/manipulated_camera_frame.h>
#include <easy3d/renderer/key_frame_interpolator.h>
#include <easy3d/core/model.h>
 
 
using namespace easy3d;
 
 
CameraInterpolation::CameraInterpolation(const std::string& title)
    : Viewer(title)
{
    interpolator_ = new KeyFrameInterpolator(camera_->frame());
    // update the viewer when the interpolation finishes
    easy3d::connect(&interpolator_->interpolation_stopped, (Viewer*)this, &Viewer::update);
 
    usage_string_ =
            "------------ Camera Interpolation usage ---------- \n"
            "Press 'K' to add key frames\n"
            "Press 'Space' to start/stop the animation\n"
            "Press 'D' to delete the camera path\n"
            "-------------------------------------------------- \n";
}
 
 
CameraInterpolation::~CameraInterpolation()
{
    delete interpolator_;
}
 
 
bool CameraInterpolation::key_press_event(int key, int modifiers)
{
    if (key == KEY_K && modifiers == 0) {
        easy3d::Frame *frame = camera()->frame();
        if (interpolator_->add_keyframe(*frame)) {
            float dist = distance(camera_->sceneCenter(), frame->position());
            if (dist > camera_->sceneRadius())
                camera_->setSceneRadius(dist);
            std::cout << "Key frame added" << std::endl;
            return true;
        }
        else
            return false;
    }
    else if (key == KEY_SPACE && modifiers == 0) {
        if (interpolator_->is_interpolation_started()) {
            interpolator_->stop_interpolation();
            std::cout << "Animation stopped" << std::endl;
        }
        else {
            interpolator_->start_interpolation();
            if (interpolator_->is_interpolation_started())
                std::cout << "Animation started" << std::endl;
        }
        return true;
    }
    else if (key == KEY_D && modifiers == 0) {
        interpolator_->delete_path();
        // update scene bounding box
        Box3 box;
        for (auto m : models_)
            box.grow(m->bounding_box());
        camera_->setSceneBoundingBox(box.min_point(), box.max_point());
        std::cout << "path deleted"<< std::endl;
        return true;
    }
    else
        return Viewer::key_press_event(key, modifiers);
}
 
 
void CameraInterpolation::draw() const {
    Viewer::draw();
 
    // shown only when it is not animating
    if (!interpolator_->is_interpolation_started()) {
        interpolator_->draw_cameras(camera(), camera()->sceneRadius() * 0.05f);
        interpolator_->draw_path(camera());
    }
}