KlassischeKeplerKriege/game/renderer_polygon_3d/image_texture.hpp

#pragma once

#include "glclasses.hpp"

#include <glm/vec2.hpp>

// based on sources of knoc/chaqu

namespace endofthejedi {

    /**
     * @brief This sprite struct stores all information needed to render an
     * arbitrary PNG texture to a quad.
     *
     * If the loaded texture dimensions have no powers of a bit more space is
     * allocated and extra padding is added.
     */
    class ImageTexture {
        public:
            ImageTexture(const std::string &filename) : m_path(filename), m_valid(false)
            {
            }

            ~ImageTexture()
            {
            }

            /**
             * @brief Try to load a PNG image from file into an opengl texture.
             *
             * @param path Path of PNG file
             * @param texture The used texture id will be saved there.
             * @param width Width of the loaded texture in pixels.
             * @param height Height of the loaded texture in pixels.
             * @param uv_scale_x Horizontal portion of the screen which is padded to get
             * power-of-two texture.
             * @param uv_scale_y Vertical portion of the screen which is padded to get
             * power-of-two texture.
             *
             * Note: The current active texture unit should be bound (GL_TEXTURE0 etc...)
             * before calling this
             *
             * @return true if loading suceeded, false on errors.
             */
            bool loadPng();

            bool valid() const { return m_valid; }

            glm::vec2 size()    const { return m_size; }
            glm::vec2 uvScale() const { return m_uvScale; }

            GLuint textureId() const { return m_texture_id; }

        public:
            std::string m_path;     // path for the loaded texture is saved here
            glm::vec2   m_size;     // used width/height of the pixels of the texture
            glm::vec2   m_uvScale;  // factor to scale uv-coordinates to get rid of non-power-of-two padding

            bool        m_valid;

            GLuint      m_texture_id;         // texture binding id
    };
}