Getting maximum possible texture size and GPU memory available

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Getting maximum possible texture size

Material is based on OpenGL Wiki page: https://www.khronos.org/opengl/wiki/Textures_-_more

    int max_tex_size;
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max_tex_size);  
    cout << "GPU maximal 2D texture size: " << max_tex_size << endl;

For 3D texture: GL_MAX_3D_TEXTURE_SIZE
For cubemap texture:GL_MAX_CUBE_MAP_TEXTURE_SIZE

Getting total and available GPU memory for NVidia cards

Material is based on the article How to Know the Graphics Memory Size and Usage In OpenGL by JEGX:
https://www.geeks3d.com/20100531/programming-tips-how-to-know-the-graphics-memory-size-and-usage-in-opengl/

    #define GL_GPU_MEM_INFO_TOTAL_AVAILABLE_MEM_NVX 0x9048    #define GL_GPU_MEM_INFO_CURRENT_AVAILABLE_MEM_NVX 0x9049

    GLint total_mem_kb = 0;
    glGetIntegerv(GL_GPU_MEM_INFO_TOTAL_AVAILABLE_MEM_NVX, &total_mem_kb);
    cout << "Nvidia GPU total memory: " << total_mem_kb / 1024 << " Mb" << endl;

    GLint cur_avail_mem_kb = 0;
    glGetIntegerv(GL_GPU_MEM_INFO_CURRENT_AVAILABLE_MEM_NVX, &cur_avail_mem_kb);
    cout << "Nvidia GPU available memory: " << cur_avail_mem_kb / 1024 << " Mb" << endl;


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