frustum.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_RENDERER_FRUSTUM_H
#define EASY3D_RENDERER_FRUSTUM_H
 
 
#include <vector>
 
#include <easy3d/core/types.h>
 
 
namespace easy3d {
 
    class Frustum
    {
    public:
        enum ProjectionType { PERSPECTIVE, ORTHO };
 
    public:
        explicit Frustum(ProjectionType type);
 
        // To define a working frustum, you need to call two functions:
        //   - orient(), defining the view matrix.
        //   - set_perspective()/set_frustum(), or set_ortho(), defining the projection matrix.
        void orient(const vec3 &pos, const vec3& at, const vec3& up);
 
        // NOTE: fovy is in radians
        void set_perspective(float fovy, float aspect, float znear, float zfar);
        void set_frustum(float frustum_width, float frustum_height, float znear, float zfar);
 
        void set_ortho(float xmin, float xmax, float ymin, float ymax, float znear, float zfar);
 
        mat4 view_matrix() const;
        mat4 projection_matrix() const;
 
        // the center point of the near/far planes in world space
        vec3  near_center() const;
        vec3  far_center() const;
 
        float near_width() const;   // frustum width at near plane
        float near_height() const;  // frustum height at near plane
 
        float far_width() const;    // frustum width at far plane
        float far_height() const;   // frustum height at far plane
 
        // in world space
        const vec3& position() const { return pos_; }
        // the up/right vector in world space
        vec3 up_vector() const;
        vec3 right_vector() const;
 
        float near_distance() const { return near_; }
        float far_distance() const { return far_; }
 
        // compute the 8 corner points in world space
        std::vector<vec3> vertices() const;
 
    private:
        ProjectionType type_;
 
        vec3 pos_;
        vec3 at_;
        vec3 up_;
 
        float near_, far_;
        float xmin_, xmax_, ymin_, ymax_;
        float fovy_, ar_;
    };
 
}
 
 
#endif // EASY3D_RENDERER_FRUSTUM_H