gl.hpp

// SPDX-License-Identifier: MIT
// Author:  Giovanni Santini
// Mail:    giovanni.santini@proton.me
// Github:  @San7o
 
//
// Helper functions to interact with OpenGL.
//
 
#pragma once
 
#include <brenta/subsystem.hpp>
 
#include <glad/glad.h> // OpenGL driver
 
#include <expected>
#include <string>
 
#define check_error() gl::_check_error(__FILE__, __LINE__)
 
namespace brenta
{
 
class gl : public subsystem
{
public:
 
  class config;
  class builder;
 
  static const std::string subsystem_name;
  static const gl::config default_config;
  static gl::config init_config;
 
  // Subsystem interface
  std::expected<void, subsystem::error> initialize() override;
  std::expected<void, subsystem::error> terminate() override;
  std::string name() override;
  bool is_initialized() override;
  
  // Constructors / destructors
  gl() = default;
  ~gl() = default;
 
  // Member functions
  
  static gl &instance();
  
  static void set_poligon_mode(GLboolean enable);
  
  static void set_viewport(int x, int y, int width, int height);
  
  static void set_color(float r, float g, float b, float a);
  
  static void draw_arrays(GLenum mode, int first, int count);
  
  static void draw_elements(GLenum mode, int count, GLenum type,
                            const void *indices);
  
  static void clear();
  
  static void bind_vertex_array(unsigned int n);
  
  static GLenum _check_error(const char *file, int line);
 
private:
  
  static bool initialized;
  
};
 
struct gl::config
{
public:
  bool enable_blending;
  bool enable_cull_face;
  bool enable_multisample;
  bool enable_depth_test;
};
  
class gl::builder : public subsystem::builder
{
private:
 
  gl::config conf = gl::default_config;
  
public:
 
  builder() = default;
  ~builder() = default;
 
  builder &blending();
  builder &cull_face();
  builder &multisample();
  builder &depth_test();
 
  subsystem &build() override;
  
};
  
} // namespace brenta