Generate an image for a model

[Josh]

This is how the editor creates thumbnails for models. @Andy90

Multi-threaded rendering needs to be disabled if you get the screenshot immediately, like this code does.

auto win = openwindows[size];
if (win == NULL)
{
    win = CreateWindow("", 0, 0, size, size, GetDisplays()[0], WINDOW_HIDDEN | WINDOW_CLIENTCOORDS);
    openwindows[size] = win;
    fb[size] = CreateFramebuffer(win);
}
if (world == NULL)
{
    world = CreateWorld();
    world->SetEnvironmentMap(LoadTexture(AppDir() + "/thumbnail_diffuse.dds"), ENVIRONMENTMAP_DIFFUSE);
    world->SetEnvironmentMap(LoadTexture(AppDir() + "/thumbnail_specular.dds"), ENVIRONMENTMAP_SPECULAR);
    world->SetAmbientLight(0);
    light = CreateDirectionalLight(world);
    light->SetShadows(false);                    
}

shared_ptr<Model> mdl;
if (packagepath.empty())
{
    mdl = LoadModel(world, path, LOAD_UNMANAGED | LOAD_NO_PACKAGES);
}
else
{
    auto pak = LoadPackage(packagepath);
    if (pak)
    {
        packages.push_back(pak);
        auto stream = pak->ReadFile(path);
        if (stream == NULL) return NULL;
        mdl = LoadModel(world, stream, LOAD_UNMANAGED);
    }
}
if (mdl)
{
    light->SetRotation(35, -35, 0);
    if (cam == NULL) cam = CreateCamera(world);
    cam->SetProjectionMode(PROJECTION_ORTHOGRAPHIC);
    cam->SetRotation(0,135,0);
    cam->Turn(22.5, 0, 0);
    auto bounds = mdl->GetBounds(BOUNDS_RECURSIVE);
    cam->SetPosition(bounds.center);
    cam->Move(0,0,-bounds.radius);
    cam->SetZoom(float(size) / (bounds.radius * 2.0f));
    cam->SetRange(0, bounds.radius * 2.0f);
    cam->Sync();
    fb[size]->Capture();
    cam->SetHidden(false);
    world->Render(fb[size]);
    cam->SetHidden(true);
    auto caps = fb[size]->GetCaptures();
    if (not caps.empty())
    {
        pixmap = caps[0];
        //pixmap->Save(GetPath(PATH_DESKTOP) + "/" + String(size) + ".dds");
        Assert(pixmap->size == fb[size]->GetSize());
    }
}