read_pixel.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_OPENGL_READ_PIXEL_H
#define EASY3D_RENDERER_OPENGL_READ_PIXEL_H
 
#include <string>
#include <vector>
 
 
namespace easy3d {
 
    namespace opengl {
 
        // NOTE: For the multisample-version functions, a normal fbo will be created for bliting color/depth from the 
        //       multisample framebuffer object. So for high-frequent queries, you'd better create a normal fbo for 
        //       bliting operations. This way, you can avoid frequently allocating and deallocating GPU memories. But, 
        //       do remember to do the cleaning when all queries are done.
 
        // read color value at pixel (x, y) from current fbo.
        // (x, y): the pixel coordinates, which are in the OpenGL coordinate system. 
        void read_color(unsigned char rgba[4], int x, int y);
        void read_color_ms(int index, unsigned char rgba[4], int x, int y); // multisample framebuffer object
 
        // read depth value at pixel (x, y) from current fbo.
        // (x, y): the pixel coordinates, which are in the OpenGL coordinate system. 
        void read_depth(float& depth, int x, int y);
        void read_depth_ms(float& depth, int x, int y);     // multisample framebuffer object
 
        // read the color data of the framebuffer into a specified buffer.
        // format: format of the pixel data. The following formats are accepted: GL_RGB, GL_BGR, GL_RGBA, and GL_BGRA.
        void read_color(int index, std::vector<unsigned char>& buffer, unsigned int format, bool flip_vertically = true);
        void read_color_ms(int index, std::vector<unsigned char>& buffer, unsigned int format, bool flip_vertically = true); // multisample framebuffer object
 
        // read the depth data of the framebuffer into a specified buffer.
        void read_depth(std::vector<float>& buffer, bool flip_vertically = true);
        void read_depth_ms(std::vector<float>& buffer, bool flip_vertically = true); // multisample framebuffer object
 
 
        // snapshot the color render buffer attached to color attachment index into an image file.
        // This is very useful for debugging.
        // Only png, jpg, bmp, tga, ppm are supported. File format is determined by the given extension.
        void snapshot_color(const std::string& file_name);
        void snapshot_color_ms(int index, const std::string& file_name);    // multisample framebuffer object
 
        // snapshot the depth render buffer into an image file. This is very useful for debugging.
        // Only png, jpg, bmp, tga, ppm are supported. File format is determined by the given extension.
        void snapshot_depth(const std::string& file_name);
        void snapshot_depth_ms(const std::string& file_name);   // multisample framebuffer object
 
    }
 
}
 
#endif // EASY3D_RENDERER_OPENGL_READ_PIXEL_H