GLuint tex;
GLbyte* loadTexture( GLint* w, GLint* h, GLint* ImComponents, GLenum* ImFormat) {
    GLbyte* image;
    int ch;
    *ImComponents = GL_RGB8;
    *ImFormat=GL_BGR_EXT;
    GLbyte* pbitsperpixel = NULL;
    image = (GLbyte*) stbi_load("t.jpg", w, h, &ch, 0);
    if (image == NULL) {
        std::cout << "error";
        exit(2137);
    }
    switch (ch)
    {
        case 3:*ImFormat = GL_BGR_EXT;*ImComponents = GL_RGB8;break;
        case 4:*ImFormat = GL_BGRA_EXT;*ImComponents = GL_RGBA8; break;
        case 1:*ImFormat = GL_LUMINANCE;*ImComponents = GL_LUMINANCE8;break;
    };
    return image;
}

void InitText() {
    GLbyte* pBytes;
    GLint ImWidth, ImHeight, ImComponents;
    GLenum ImFormat;
    glEnable(GL_CULL_FACE);
    glCullFace(GL_FRONT);
    pBytes = loadTexture(&ImWidth, &ImHeight, &ImComponents, &ImFormat);
    glTexImage2D(GL_TEXTURE_2D, 0, ImComponents, ImWidth, ImHeight, 0, ImFormat, GL_UNSIGNED_BYTE, pBytes);
    free(pBytes);
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, 0);
    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
}