spacebox/src/Texture.cpp

       /*         +------------------------------------------------------+ 
  ____/  \____   /| - Open source game framework licensed to freely use, |
  \          /  / |   copy, modify and sell without restriction          |
+--\ ^__^   /--+  |                                                      |
| ~/        \~ |  | - created for <https://foam.shampoo.ooo>             |
| ~~~~~~~~~~~~ |  +------------------------------------------------------+
| SPACE ~~~~~  | /
|  ~~~~~~~ BOX |/
+-------------*/

#include "Texture.hpp"
using namespace sb;

/* Have to pass our deleter to abstract base class at instantiation */
Texture::Texture() : GLObject(texture_deleter) {}

/* If an image path is passed at creation, the path will be stored in the class for later loading */
Texture::Texture(fs::path path) : Texture()
{
    associate(path);
}

/* Store an image path as a member variable for loading later. Each texture should have one image
 * path (support for multiple mipmap levels may be added later) */
void Texture::associate(fs::path path)
{
    this->path = path;
}

/* Forward the GL texture generate function to the base class */
void Texture::generate()
{
    GLObject::generate(glGenTextures);
}

/* Generate a GL_TEXTURE_2D texture ID and allocate GL_RGBA8 storage for the given size */
void Texture::generate(glm::vec2 size)
{
    generate();
    bind();
    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, size.x, size.y);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    sb::Log::gl_errors();
}

void Texture::load()
{
    if (!path.empty())
    {
        load(path);
    }
    else
    {
        std::ostringstream message;
        message << "Cannot load, no path has been specified yet for texture " << id();
        sb::Log::log(message, sb::Log::WARN);
    }
}

void Texture::load(fs::path path)
{
    std::ostringstream message;
    sb::Log::Level message_level;
    if (path.has_filename())
    {
        /* Load file path as a surface object to access pixel data and flip into OpenGL orientation. Attach a destructor so it will free
         * itself when it goes out of scope at the end of this function. */
        std::unique_ptr<SDL_Surface, decltype(&SDL_FreeSurface)> surface(IMG_Load(path.c_str()), SDL_FreeSurface);
        std::unique_ptr<SDL_Surface, decltype(&SDL_FreeSurface)> flipped_surface(rotozoomSurfaceXY(surface.get(), 0, 1, -1, 0), SDL_FreeSurface);
        load(flipped_surface.get());
        message << "Loading image at " << path;
        message_level = sb::Log::INFO;
    }
    else
    {
        message << "Cannot load, " << path << " is not a vaild path to a file";
        message_level = sb::Log::WARN;
    }
    sb::Log::log(message, message_level);
}

void Texture::load(SDL_RWops* rw)
{
    /* Load RW object as path as a surface object to access pixel data and flip into OpenGL orientation. Attach a destructor so it will free
     * itself when it goes out of scope at the end of this function. */
    std::unique_ptr<SDL_Surface, decltype(&SDL_FreeSurface)> surface(IMG_Load_RW(rw, 0), SDL_FreeSurface);
    std::unique_ptr<SDL_Surface, decltype(&SDL_FreeSurface)> flipped_surface(rotozoomSurfaceXY(surface.get(), 0, 1, -1, 0), SDL_FreeSurface);
    load(flipped_surface.get());
}

void Texture::load(SDL_Surface* surface)
{
    std::ostringstream message;
    sb::Log::Level message_level;
    if (surface->w > 0 && surface->h > 0)
    {
        message << "Loading image from SDL surface (" << surface->w << "×" << surface->h << ", " << SDL_GetPixelFormatName(surface->format->format) << ")";
        load(surface->pixels, {surface->w, surface->h}, GL_RGBA, GL_UNSIGNED_BYTE);
        message_level = sb::Log::DEBUG;
    }
    else
    {
        message << "Cannot load into texture, invalid image data without dimensions found";
        message_level = sb::Log::WARN;
    }
    sb::Log::log(message, message_level);
}

void Texture::load(void* pixels, glm::vec2 size, GLenum format, GLenum type)
{
    std::ostringstream message;
    sb::Log::Level message_level;
    if (size.x > 0 && size.y > 0)
    {
        if (!generated())
        {
            generate(size);
        }
        bind();
        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, size.x, size.y, format, type, pixels);
        message << "Loaded " << size.x << "×" << size.y << " image into texture ID " << id();
        message_level = sb::Log::DEBUG;
    }
    else
    {
        message << "Cannot load pixels with zero or negative size in either dimension";
        message_level = sb::Log::WARN;
    }
    sb::Log::log(message, message_level);
    sb::Log::gl_errors("after loading texture");
}

void Texture::bind() const
{
    glBindTexture(GL_TEXTURE_2D, this->id());
}

/* glGetTexlevelparameteriv is not available in OpenGL ES 3.0 */
#if !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !defined(ANDROID)
void Texture::load(void* pixels, GLenum format, GLenum type)
{
    if (!generated())
    {
        throw std::invalid_argument("This texture has not been generated and has no size property, so a size must be provided");
    }
    else
    {
        load(pixels, size(), format, type);
    }
}

glm::vec2 Texture::size() const
{
    if (generated())
    {
        bind();
        int width, height;
        int miplevel = 0;
        glGetTexLevelParameteriv(GL_TEXTURE_2D, miplevel, GL_TEXTURE_WIDTH, &width);
        glGetTexLevelParameteriv(GL_TEXTURE_2D, miplevel, GL_TEXTURE_HEIGHT, &height);
        return {width, height};
    }
    else
    {
        return {0, 0};
    }
}
#endif

/* Textures are considered equal if they have the same ID */
bool Texture::operator==(const Texture& texture) const
{
    return id() == texture.id();
}

/* This function gets passed to the abstract base class for deleting the texture data when the ID
 * pointer goes out of scope (when all instances of this texture and its copies are out of scope) */
void sb::texture_deleter(GLuint* id)
{
    /* not sure why SDL_Log works here at program end but SDL_LogDebug and SDL_LogInfo don't */
    SDL_Log("destroying texture ID %i", *id);
    glDeleteTextures(1, id);
}