shader_manager.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_SHADER_MANAGER_H
#define EASY3D_RENDERER_SHADER_MANAGER_H
 
#include <string>
#include <unordered_map>
 
#include <easy3d/renderer/shader_program.h>
 
 
namespace easy3d {
 
    class ShaderProgram;
 
    class ShaderManager
    {
    public:
        // return the shader program if it exists and is working, otherwise return 0.
        // shader_name: the base name of the program's source file.
        static ShaderProgram* get_program(const std::string& shader_name);
 
        // create a shader program from shader source files specified by the shader file's base name.
        static ShaderProgram* create_program_from_files(
            const std::string& file_base_name,
            const std::vector<ShaderProgram::Attribute>& attributes = std::vector<ShaderProgram::Attribute>(),
            const std::vector<std::string>& outputs = std::vector<std::string>(),
            bool geom_shader = false
        );
 
        // create a shader program from shader source files specified by individual file names.
        // This function allows user providing extra code.
        static ShaderProgram* create_program_from_files(
            const std::string& vert_file_name,
            const std::string& frag_file_name,
            const std::string& geom_file_name = "",
            const std::string& extra_vert_code = "",
            const std::string& extra_frag_code = "",
            const std::string& extra_geom_code = "",
            const std::vector<ShaderProgram::Attribute>& attributes = std::vector<ShaderProgram::Attribute>(),
            const std::vector<std::string>& outputs = std::vector<std::string>()
        );
 
        // create a shader program from completed shader source codes
        static ShaderProgram* create_program_from_codes(
                const std::string& vert_code,
                const std::string& frag_code,
                const std::string& geom_code = "",
                const std::vector<ShaderProgram::Attribute>& attributes = std::vector<ShaderProgram::Attribute>(),
                const std::vector<std::string>& outputs = std::vector<std::string>()
        );
 
        static std::vector<ShaderProgram*> all_programs();
 
        // destroy all shader programs.
        static void terminate();
 
        static void reload();
 
    private:
        // maps of std::string can be super slow when calling find with a string literal or const char*
        // as find forces construction/copy/destruction of a std::sting copy of the const char*.
        static std::unordered_map<std::string, ShaderProgram*>  programs_;
        static std::unordered_map<std::string, bool>            attempt_load_program_; // avoid multiple attempt
    };
 
}
 
 
#endif  // EASY3D_RENDERER_SHADER_MANAGER_H