spacebox/src/Texture.cpp

#include "Texture.hpp"

/* 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;
}

/* Generate an ID for this Texture and save it */
void Texture::generate()
{
    GLuint id;
    glGenTextures(1, &id);
    this->id(id);
}

/* Generate a GL_TEXTURE_2D texture ID and allocate GL_RGB8 storage for the given size */
void Texture::generate(glm::vec2 size)
{
    generate();
    bind();
    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGB8, size.x, size.y);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    Game::log_gl_errors();
}

/* When called with no parameters, use the stored path variable */
void Texture::load()
{
    load(path);
}

/* Create an SDL Surface from the supplied path and forward it to the loading function which accepts
 * a surface pointer */
void Texture::load(fs::path path)
{
    /* open path as surface which 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());
}

/* Create an SDL Surface from the supplied RW pointer and forward it to the loading function which accepts
 * a surface pointer */
void Texture::load(SDL_RWops* rw)
{
    /* load RW as an SDL surface to translate image format into pixel data, flip, and get dimensions */
    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());
}

/* Forward pixels and size to the generic pixel loading function */
void Texture::load(SDL_Surface* surface)
{
    load(surface->pixels, {surface->w, surface->h}, GL_RGBA, GL_UNSIGNED_BYTE);
    std::ostringstream message;
    message << "loaded " << path << " (" << surface->w << "x" << surface->h << ")";
    Game::log(message.str());
}

/* Bind texture and load pixel data using this class's generated ID */
void Texture::load(void* pixels, glm::vec2 size, GLenum format, GLenum type)
{
    if (!generated())
    {
        generate(size);
    }
    bind();
    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, size.x, size.y, format, type, pixels);
    Game::log_gl_errors();
}

/* The texture must have been previously generated with a size to use this generic pixel data load function */
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);
    }
}

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

/* Return the size in pixels of mipmap level 0 (the only mipmap level supported by this class). If the texture hasn't been,
 * generated, return {0, 0}. */
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};
    }
}

/* 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 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);
}