GLTexture.h

#ifndef NTA_GLTEXTURE_H_INCLUDED
#define NTA_GLTEXTURE_H_INCLUDED
 
#include <GL/glew.h>
 
#include "nta/Errors.h"
 
namespace nta {
    struct RawTexture {
        bool operator==(const RawTexture& rhs) const {
            return data == rhs.data;
        }
 
        GLuint width, height;
        GLenum format;
        GLubyte* data = nullptr;
    };
    struct GLTexture {
        GLTexture() : id(0) {}
        GLTexture(const RawTexture& raw, GLint minFilt = GL_LINEAR_MIPMAP_LINEAR,
                  GLint magFilt = GL_LINEAR) : id(0) { init(raw, minFilt, magFilt); }
        void init(const RawTexture& raw, GLint minFilt = GL_LINEAR_MIPMAP_LINEAR,
                  GLint magFilt = GL_LINEAR);
 
        static GLTexture no_texture() {
            GLTexture ret;
            ret.id = ret.width = ret.height = 0;
            return ret;
        }
        static GLTexture combine_horizontal(const GLTexture& lhs, const GLTexture& rhs);
        static GLTexture combine_vertical(const GLTexture& lhs, const GLTexture& rhs);
 
        bool is_valid() const {
            return id != 0;
        }
        bool operator==(const GLTexture& rhs) const {
            return id == rhs.id;
        }
        bool operator<(const GLTexture& rhs) const {
            return id < rhs.id;
        }
        GLTexture operator+(const GLTexture& rhs) const {
            return combine_horizontal(*this, rhs);
        }
        GLTexture operator*(const GLTexture& rhs) const {
            return combine_vertical(*this, rhs);
        }
 
        void destroy() { glDeleteTextures(1, &id); }
 
        GLuint id;
        GLint width, height;
    };
    class ImageLoader {
    private:
        static Result<GLTexture> readImage(crstring filePath, GLint minFilt, 
                                           GLint magFilt, crvec2 dimensions);
        static Result<RawTexture> readImage(crstring filePath, crvec2 dimensions);
    public:
        friend class ResourceManager;
    };
}
 
namespace std {
  template <>
  struct hash<nta::GLTexture> {
    std::size_t operator()(const nta::GLTexture& tex) const { 
        return std::hash<GLuint>()(tex.id); 
    }
  };
}
 
#endif // NTA_GLTEXTURE_H_INCLUDED