Tutorial_403_PointSelection/main.cpp

This example shows how to select a subset of a point cloud by sketching a rectangle or a lasso using the mouse.

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_TUTORIAL_POINT_SELECTION_H
#define EASY3D_TUTORIAL_POINT_SELECTION_H
 
#include <easy3d/viewer/viewer.h>
 
 
namespace easy3d {
    class PointCloud;
}
 
class TutorialPointSelection : public easy3d::Viewer
{
public:
    explicit TutorialPointSelection(const std::string& title = "PointSelection");
 
private:
    bool mouse_press_event(int x, int y, int button, int modifiers) override;
    bool mouse_release_event(int x, int y, int button, int modifiers) override;
    bool mouse_drag_event(int x, int y, int dx, int dy, int button, int modifiers) override;
 
    // This function will be called after the main draw procedure.
    // It draws the axes of the coordinate system, the sketching rectangle/lasso, etc. overlaid on the scene.
    void post_draw() override;
 
    // highlight the selection
    void mark_selection(easy3d::PointCloud* cloud);
 
private:
    easy3d::Polygon2 polygon_;
};
 
 
#endif // EASY3D_TUTORIAL_POINT_SELECTION_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/opengl.h>
#include <easy3d/core/point_cloud.h>
#include <easy3d/gui/picker_point_cloud.h>
#include <easy3d/renderer/shape.h>
#include <easy3d/renderer/drawable_points.h>
#include <easy3d/renderer/renderer.h>
#include <easy3d/util/logging.h>
 
 
#define  USE_LASSO   1
 
using namespace easy3d;
 
// \cond
 
TutorialPointSelection::TutorialPointSelection(const std::string &title) : Viewer(title) {
    hint_ = "Pressing Shift, drag the mouse to select (left) or deselect (right) points";
}
 
 
bool TutorialPointSelection::mouse_press_event(int x, int y, int button, int modifiers) {
    if (modifiers == MODIF_SHIFT) {
        polygon_.clear();
        polygon_.push_back(vec2(static_cast<float>(x), static_cast<float>(y)));
        return false;
    } else
        return Viewer::mouse_press_event(x, y, button, modifiers);
}
 
 
bool TutorialPointSelection::mouse_release_event(int x, int y, int button, int modifiers) {
    if (modifiers == MODIF_SHIFT) {
        if (polygon_.size() >= 3) {
            auto cloud = dynamic_cast<PointCloud *>(current_model());
            if (cloud) {
                PointCloudPicker picker(camera());
#if USE_LASSO
                picker.pick_vertices(cloud, polygon_, button == BUTTON_RIGHT);
#else
                picker.pick_vertices(cloud, Rect(polygon_[0], polygon_[2]), button == BUTTON_RIGHT);
#endif
                mark_selection(cloud);
 
                polygon_.clear();
            }
        }
        return false;
    } else
        return Viewer::mouse_release_event(x, y, button, modifiers);
}
 
 
bool TutorialPointSelection::mouse_drag_event(int x, int y, int dx, int dy, int button, int modifiers) {
    if (modifiers == MODIF_SHIFT) {
#if USE_LASSO
        polygon_.push_back(vec2(static_cast<float>(x), static_cast<float>(y)));
#else   // rectangle
        const vec2 first_point = polygon_[0];
        polygon_.clear();
        polygon_.push_back(first_point);
        polygon_.push_back(vec2(first_point.x, static_cast<float>(y)));
        polygon_.push_back(vec2(static_cast<float>(x), static_cast<float>(y)));
        polygon_.push_back(vec2(static_cast<float>(x), first_point.y));
#endif
        return false;
    } else
        return Viewer::mouse_drag_event(x, y, dx, dy, button, modifiers);
}
 
 
void TutorialPointSelection::post_draw() {
    Viewer::post_draw();
 
    if (polygon_.size() >= 3) {
        // draw the boundary of the rect/lasso
        shape::draw_polygon_wire(polygon_, vec4(1.0f, 0.0f, 0.0f, 1.0f), width(), height(), -1.0f);
 
        // draw its transparent face
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        shape::draw_polygon_filled(polygon_, vec4(1.0f, 0.0f, 0.0f, 0.2f), width(), height(), -0.9f);
        glDisable(GL_BLEND);
    }
}
 
 
void TutorialPointSelection::mark_selection(PointCloud *cloud) {
    auto drawable = cloud->renderer()->get_points_drawable("vertices");
    auto select = cloud->vertex_property<bool>("v:select");
    auto colors = cloud->vertex_property<vec3>("v:color");
    for(auto v : cloud->vertices())
        colors[v] = select[v] ? vec3(1,0,0) : drawable->color().xyz();    // mark selected points red
    drawable->set_coloring(easy3d::State::COLOR_PROPERTY, easy3d::State::VERTEX, "v:color");
    drawable->update();
}
 
// \endcond

/********************************************************************
 * 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/core/model.h>
#include <easy3d/renderer/drawable_points.h>
#include <easy3d/renderer/renderer.h>
#include <easy3d/util/resource.h>
#include <easy3d/util/initializer.h>
 
using namespace easy3d;
 
 
int main(int argc, char **argv) {
    // initialize Easy3D.
    initialize();
 
    const std::string file = resource::directory() + "/data/polyhedron.bin";
 
    // create the viewer.
    TutorialPointSelection viewer(EXAMPLE_TITLE);
 
    auto model = viewer.add_model(file, true);
    if (!model) {
        LOG(ERROR) << "failed to load model. Please make sure the file exists and format is correct.";
        return EXIT_FAILURE;
    }
 
    auto drawable = model->renderer()->get_points_drawable("vertices");
    dynamic_cast<PointsDrawable*>(drawable)->set_point_size(3.0f);
 
    // run the viewer
    return viewer.run();
}