Tutorial_501_AmbientOcclusion

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/core/model.h>
#include <easy3d/renderer/drawable_triangles.h>
#include <easy3d/renderer/renderer.h>
#include <easy3d/util/resource.h>
#include <easy3d/util/initializer.h>
 
 
using namespace easy3d;
 
// This example shows how to
//      - renders a surface mesh using ambient occlusion to improve depth perception.e.
 
 
int main(int argc, char **argv) {
    // initialize Easy3D.
    initialize();
 
    const std::string file = resource::directory() + "/data/general_open.obj";
 
    // create the viewer.
    TutorialAmbientOcclusion viewer(EXAMPLE_TITLE);
 
    Model *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_triangles_drawable("faces");
    drawable->set_uniform_coloring(vec4(1.0f, 1.0f, 1.0f, 1.0f));
 
    // run the viewer
    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_TUTORIAL_AMBIENT_OCCLUSION_H
#define EASY3D_TUTORIAL_AMBIENT_OCCLUSION_H
 
#include <easy3d/viewer/viewer.h>
 
 
// This class renders a surface mesh with ambient occlusion to improve depth perception.
 
namespace easy3d {
    class AmbientOcclusion;
}
 
 
class TutorialAmbientOcclusion : public easy3d::Viewer
{
public:
    explicit TutorialAmbientOcclusion(const std::string& title = "");
    ~TutorialAmbientOcclusion() override;
 
protected:
    bool key_press_event(int key, int modifiers) override;
    void draw() const override;
 
private:
    easy3d::AmbientOcclusion* ao_;
    bool ao_enabled_;
};
 
 
#endif // EASY3D_TUTORIAL_AMBIENT_OCCLUSION_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/core/surface_mesh.h>
#include <easy3d/renderer/camera.h>
#include <easy3d/renderer/drawable_triangles.h>
#include <easy3d/renderer/ambient_occlusion.h>
#include <easy3d/renderer/shader_manager.h>
#include <easy3d/renderer/shader_program.h>
#include <easy3d/renderer/shape.h>
#include <easy3d/renderer/renderer.h>
#include <easy3d/util/setting.h>
 
 
using namespace easy3d;
 
TutorialAmbientOcclusion::TutorialAmbientOcclusion(const std::string& title) : Viewer(title) {
    ao_ = new AmbientOcclusion(camera());
    ao_enabled_ = true;
 
    usage_string_ =
            "----------------------- Ambient Occlusion usage ------------------------- \n"
            "Press key 'space' to switch between Ambient Occlusion and normal rendering\n"
            "Press 'up/down' to increase/decrease the radius                           \n"
            "------------------------------------------------------------------------- \n";
}
 
 
TutorialAmbientOcclusion::~TutorialAmbientOcclusion() {
    delete ao_;
 
    // Not needed: it will be called in the destructor of the base class
    //Viewer::cleanup();
}
 
 
bool TutorialAmbientOcclusion::key_press_event(int key, int modifiers) {
    if (key == KEY_SPACE) {
        ao_enabled_ = !ao_enabled_;
        update();
        return true;
    } else if (key == KEY_DOWN) {
        if (ao_enabled_) {
            float r = ao_->radius();
            if (r > 0)
                ao_->set_radius(r - 0.1f);
            // make sure it is valid
            if (ao_->radius() <= 0)
                ao_->set_radius(0.1f);
            std::cout << "radius: " << ao_->radius() << std::endl;
            update();
        }
        return true;
    } else if (key == KEY_UP) {
        if (ao_enabled_) {
            float r = ao_->radius();
            if (r > 0)
                ao_->set_radius(r + 0.1f);
            // make sure it is valid
            if (ao_->radius() >= 1.0f)
                ao_->set_radius(1.0f);
            std::cout << "radius: " << ao_->radius() << std::endl;
            update();
        }
        return true;
    } else
        return Viewer::key_press_event(key, modifiers);
}
 
 
void TutorialAmbientOcclusion::draw() const {
    if (!current_model()) {
        return;
    }
 
    auto drawable = current_model()->renderer()->get_triangles_drawable("faces");
    auto faces = dynamic_cast<TrianglesDrawable*>(drawable);
    if (!faces)
        return;
 
    if (ao_enabled_) {
        ao_->generate(models_);
 
        const mat4& MVP = camera_->modelViewProjectionMatrix();
        // camera position is defined in world coordinate system.
        const vec3& wCamPos = camera_->position();
        // it can also be computed as follows:
        //const vec3& wCamPos = invMV * vec4(0, 0, 0, 1);
        const mat4& MV = camera_->modelViewMatrix();
        const vec4& wLightPos = inverse(MV) * setting::light_position;
 
        ShaderProgram* program = ShaderManager::get_program("surface/surface");
        if (!program) {
            std::vector<ShaderProgram::Attribute> attributes = {
                    ShaderProgram::Attribute(ShaderProgram::POSITION, "vtx_position"),
                    ShaderProgram::Attribute(ShaderProgram::TEXCOORD, "vtx_texcoord"),
                    ShaderProgram::Attribute(ShaderProgram::COLOR, "vtx_color"),
                    ShaderProgram::Attribute(ShaderProgram::NORMAL, "vtx_normal")
            };
            program = ShaderManager::create_program_from_files("surface/surface", attributes);
        }
        if (!program)
            return;
 
        program->bind();
        program->set_uniform("MVP", MVP)
            ->set_uniform("wLightPos", wLightPos)
            ->set_uniform("wCamPos", wCamPos)
            ->set_uniform("ssaoEnabled", true)
            ->bind_texture("ssaoTexture", ao_->ssao_texture(), 0);
 
        program->set_uniform("smooth_shading", faces->smooth_shading())
            ->set_block_uniform("Material", "ambient", faces->material().ambient)
            ->set_block_uniform("Material", "specular", faces->material().specular)
            ->set_block_uniform("Material", "shininess", &faces->material().shininess)
            ->set_uniform("per_vertex_color", faces->coloring_method() != State::UNIFORM_COLOR && drawable->color_buffer())
            ->set_uniform("default_color", faces->color());
 
        const auto& range = faces->highlight_range();
        program->set_uniform("highlight_id_min", range.first)
            ->set_uniform("highlight_id_max", range.second);
 
        faces->gl_draw();
 
        program->release_texture();
        program->release();
 
        const float x = 20.0f * dpi_scaling();
        const float y = 40.0f * dpi_scaling();
        const float w = static_cast<float>(width()) / 4.0f * dpi_scaling();
        const float h = static_cast<float>(height()) / 4.0f * dpi_scaling();
        const Rect quad(x, x+w, y, y+h);
        shape::draw_depth_texture(quad, ao_->ssao_texture(), static_cast<int>(static_cast<float>(width()) * dpi_scaling()), static_cast<int>(static_cast<float>(height()) * dpi_scaling()), -0.9f);
        shape::draw_quad_wire(quad, vec4(1, 0,0, 1), static_cast<int>(static_cast<float>(width()) * dpi_scaling()), static_cast<int>(static_cast<float>(height()) * dpi_scaling()), -0.99f);
    }
    else
        Viewer::draw();
}