gedeng/include/Gedeng/Shader.h

#pragma once

// Adapted from LearnOpenGL

// Must be the first include
#include "Gedeng/Logger.h"
#include <glad/glad.h>

// Other includes
#include <GLFW/glfw3.h>
#include <glm/glm.hpp>

#include <fstream>
#include <iostream>
#include <sstream>
#include <string>

namespace Gedeng {

class Shader {
  private:
    unsigned int load_shader(const char *path, GLuint type) {
        std::string code;
        std::ifstream file;

        file.open(path);
        std::stringstream shader_stream;
        shader_stream << file.rdbuf();
        file.close();

        code = shader_stream.str();
        const char *code_charptr = code.c_str();

        unsigned int shader = glCreateShader(type);
        glShaderSource(shader, 1, &code_charptr, NULL);
        glCompileShader(shader);
        checkCompileErrors(shader, "ANY");

        return shader;
    }

  public:
    unsigned int ID;

    Shader() : ID(glCreateProgram()) {
    }

    Shader(const char *vertex_path, const char *fragment_path, const char *geometry_path = nullptr) : Shader() {
        add_vertex_shader(vertex_path);
        add_fragment_shader(fragment_path);
        if (geometry_path) add_geometry_shader(geometry_path);

        link();
    }

    void add_vertex_shader(const char *path) {
        unsigned int shader = load_shader(path, GL_VERTEX_SHADER);
        glAttachShader(ID, shader);
        glDeleteShader(shader);
    }

    void add_fragment_shader(const char *path) {
        unsigned int shader = load_shader(path, GL_FRAGMENT_SHADER);
        glAttachShader(ID, shader);
        glDeleteShader(shader);
    }

    void add_geometry_shader(const char *path) {
        unsigned int shader = load_shader(path, GL_GEOMETRY_SHADER);
        glAttachShader(ID, shader);
        glDeleteShader(shader);
    }

    void add_transform_feedback(const char **varyings, size_t varying_count) {
        for (size_t i = 0; i < varying_count; i++) { // TODO: Is this loop required?
            glTransformFeedbackVaryings(ID, varying_count, varyings, GL_INTERLEAVED_ATTRIBS);
        }
    }

    void link() {
        glLinkProgram(ID);
        checkCompileErrors(ID, "PROGRAM");
    }

    // activate the shader
    // ------------------------------------------------------------------------
    void use() {
        glUseProgram(ID);
    }
    // utility uniform functions
    // ------------------------------------------------------------------------
    void setBool(const std::string &name, bool value) const {
        glUniform1i(getUniformLocation(name), (int)value);
    }
    // ------------------------------------------------------------------------
    void setInt(const std::string &name, int value) const {
        glUniform1i(getUniformLocation(name), value);
    }
    // ------------------------------------------------------------------------
    void setFloat(const std::string &name, float value) const {
        glUniform1f(getUniformLocation(name), value);
    }
    // ------------------------------------------------------------------------
    void setVec2(const std::string &name, const glm::vec2 &value) const {
        glUniform2fv(getUniformLocation(name), 1, &value[0]);
    }
    void setVec2(const std::string &name, float x, float y) const {
        glUniform2f(getUniformLocation(name), x, y);
    }
    // ------------------------------------------------------------------------
    void setVec3(const std::string &name, const glm::vec3 &value) const {
        glUniform3fv(getUniformLocation(name), 1, &value[0]);
    }
    void setVec3(const std::string &name, float x, float y, float z) const {
        glUniform3f(getUniformLocation(name), x, y, z);
    }
    // ------------------------------------------------------------------------
    void setVec4(const std::string &name, const glm::vec4 &value) const {
        glUniform4fv(getUniformLocation(name), 1, &value[0]);
    }
    void setVec4(const std::string &name, float x, float y, float z, float w) {
        glUniform4f(getUniformLocation(name), x, y, z, w);
    }
    // ------------------------------------------------------------------------
    void setMat2(const std::string &name, const glm::mat2 &mat) const {
        glUniformMatrix2fv(getUniformLocation(name), 1, GL_FALSE, &mat[0][0]);
    }
    // ------------------------------------------------------------------------
    void setMat3(const std::string &name, const glm::mat3 &mat) const {
        glUniformMatrix3fv(getUniformLocation(name), 1, GL_FALSE, &mat[0][0]);
    }
    // ------------------------------------------------------------------------
    void setMat4(const std::string &name, const glm::mat4 &mat) const {
        glUniformMatrix4fv(getUniformLocation(name), 1, GL_FALSE, &mat[0][0]);
    }

  private:
    GLint getUniformLocation(const std::string &name) const {
        GLint location = glGetUniformLocation(ID, name.c_str());
        if (location == -1) {
            GG_CORE_ERROR("Invalid uniform location: " + name);
        }
        return location;
    }

    // utility function for checking shader compilation/linking errors.
    // ------------------------------------------------------------------------
    void checkCompileErrors(GLuint shader, std::string type) {
        GLint success;
        GLchar infoLog[1024];
        if (type != "PROGRAM") {
            glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
            if (!success) {
                glGetShaderInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::SHADER_COMPILATION_ERROR of type: " << type << "\n"
                          << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        } else {
            glGetProgramiv(shader, GL_LINK_STATUS, &success);
            if (!success) {
                glGetProgramInfoLog(shader, 1024, NULL, infoLog);
                std::cout << "ERROR::PROGRAM_LINKING_ERROR of type: " << type << "\n"
                          << infoLog << "\n -- --------------------------------------------------- -- " << std::endl;
            }
        }
    }
};

} // namespace Gedeng