Background.cpp

#include <experimental/filesystem>
namespace fs = std::experimental::filesystem;

#include <stb_image.h>
#include <glad.h>

#include "Background.hpp"
#include "Shader.hpp"

Background::Background() noexcept :
    shader(new Shader("image"))
{
    shader->use();
    shader->pass("opacity", 1.0f);
    shader->disuse();

    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    {
        int width, height;
        fs::path const path = fs::current_path() / "gamedata" / "images" / "background.jpg";
        unsigned char *const texture = stbi_load(path.u8string().c_str(), &width, &height, nullptr, STBI_rgb);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, texture);
        stbi_image_free(texture);
    }

    glBindTexture(GL_TEXTURE_2D, NULL);

    glGenVertexArrays(1, &VAO);
    glBindVertexArray(VAO);

    int4u VBO;
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);

    {
        float const vertices[30] {
            -1.0f, -1.0f, 0.0f, 0.0f, 0.0f,
            -1.0f,  1.0f, 0.0f, 0.0f, 1.0f,
             1.0f,  1.0f, 0.0f, 1.0f, 1.0f,
            -1.0f, -1.0f, 0.0f, 0.0f, 0.0f,
             1.0f, -1.0f, 0.0f, 1.0f, 0.0f,
             1.0f,  1.0f, 0.0f, 1.0f, 1.0f
        };

        glBufferData(GL_ARRAY_BUFFER, 30 * sizeof(float), vertices, GL_STATIC_DRAW);
    }

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), nullptr);
    glEnableVertexAttribArray(0);

    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), reinterpret_cast <void*> (3 * sizeof(float)));
    glEnableVertexAttribArray(1);

    glBindBuffer(GL_ARRAY_BUFFER, NULL);
    glBindVertexArray(NULL);

    glDeleteBuffers(1, &VBO);
}

void Background::render() const noexcept {
    shader->use();

    glBindVertexArray(VAO);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, texture);
    glDrawArrays(GL_TRIANGLES, 0, 6);
    glBindTexture(GL_TEXTURE_2D, NULL);
    glBindVertexArray(NULL);

    shader->disuse();
}

Background::~Background() {
    glDeleteVertexArrays(1, &VAO);
    glDeleteTextures(1, &texture);

    delete shader;
}