texture.cpp

#define STB_IMAGE_IMPLEMENTATION
#include <glad/glad.h>
#include <glcore/texture.h>
#include <iostream>
#include <stb_image.h>

using vec = std::vector<unsigned char>;

Texture::Texture(const vec &data, int width, int height, int nrChannels)
    : width_(width), height_(height), nrChannels_(nrChannels) {
  build(data.data());
}

Texture::Texture(const std::string &path) {
  stbi_set_flip_vertically_on_load(true);
  unsigned char *data =
      stbi_load(path.c_str(), &width_, &height_, &nrChannels_, 0);
  if (data) {
    build(data);
  } else {
    std::cerr << "Failed to load texture (" << path << ")" << std::endl;
  }
  stbi_image_free(data);
}

Texture::Texture(Texture &&o)
    : id_(o.id_), width_(o.width_), height_(o.height_),
      nrChannels_(o.nrChannels_) {
  o.id_ = 0;
}
Texture &Texture::operator=(Texture &&o) {
  if (id_) glDeleteTextures(1, &id_);
  id_ = o.id_;
  width_ = o.width_;
  height_ = o.height_;
  nrChannels_ = o.nrChannels_;
  o.id_ = 0;
  o.width_ = 0;
  o.height_ = 0;
  o.nrChannels_ = 0;
  return *this;
}

Texture::~Texture() {
  if (id_) {
    glDeleteTextures(1, &id_);
  }
}

void Texture::build(const unsigned char *data) {
  unsigned int format;
  switch (nrChannels_) {
  case 3:
    format = GL_RGB;
    break;
  case 4:
    format = GL_RGBA;
    break;
  default:
    format = 0;
    std::cerr << "Unknown format (" << nrChannels_ << ")" << std::endl;
    break;
  }
  glGenTextures(1, &id_);
  glBindTexture(GL_TEXTURE_2D, id_);

  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
                  GL_LINEAR_MIPMAP_LINEAR);
  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

  glTexImage2D(GL_TEXTURE_2D, 0, format, width_, height_, 0, format,
               GL_UNSIGNED_BYTE, data);
  glGenerateMipmap(GL_TEXTURE_2D);
}

void Texture::bind() { glBindTexture(GL_TEXTURE_2D, id_); }