Loading assets in the background?

[SpiderPig]

I'm not sure how to go about creating a loading screen where I can load all the assets in the background.  Does Ultra support this out of the box or do I have to code some thread magic myself?

I need to be able to update a progress bar and / or a spinning 3D object in the corner of the screen without any pauses.

[Yue]

A background thread loads the elements and the main thread would show the loading bar or animation.

[SpiderPig]

I'm not sure if we can call such things like : LoadModel() & LoadTexture() on a separate thread though.  I think it might break something in the engine.  But I'm unsure...

[Yue]

 

I have thought that if you can, as long as you don't run a render of the world. 

Possibly it will go into the main loop after doing the load. 

 

[SpiderPig]

Yeah maybe it can.  But I want to render the loading screen as well, so everything needs to be thread safe.

[Yue]

Synchronization between the two threads in mutex programming.

[Josh]

If you have called World::Render once, then the rendering thread will just keep rendering as the map is loading on the main thread.

You can use a custom shader to display a spinning object, or wait for texture animation to be added, and you can make a circular object with a scrolling texture.

[SpiderPig]

I see, thanks.  Could the application go non responsive though?

[Dreikblack]

Tried to replicate how i made loading screen in my game but for some reason loading screen shows with big delay in this example

 

#include "UltraEngine.h"
#include "ComponentSystem.h"

using namespace UltraEngine;

shared_ptr<World> gameWorld;

shared_ptr<World> world;
shared_ptr<Interface> ui;

shared_ptr<Camera> uiCamera;
shared_ptr<Map> gameScene;

shared_ptr<Window> window;
shared_ptr<Framebuffer> framebuffer;

shared_ptr<World> loadingWorld;
shared_ptr<Interface> loadingUi;
shared_ptr<Camera> loadingCamera;
shared_ptr<Widget> loadingLabel;

shared_ptr<Widget> menuPanel;
bool isMainMenuOn = true;

bool newGameButtonCallback(const Event& ev, shared_ptr<Object> extra)
{
    ui = nullptr;
    world = nullptr;
    loadingWorld->Render(framebuffer);
    WString mapName = "Maps/start.ultra";
    gameScene = LoadMap(gameWorld, mapName);
    isMainMenuOn = false;
    return true;
}

bool exitButtonCallback(const Event& ev, shared_ptr<Object> extra)
{
    exit(0);
    return true;
}

void loadingInit() 
{
    loadingWorld = CreateWorld();
    //Loading UI
    auto font = LoadFont("Fonts/arial.ttf");
    loadingUi = CreateInterface(loadingWorld, font, framebuffer->GetSize());
    loadingUi->SetScale(1);
    loadingUi->SetRenderLayers(2);
    loadingUi->LoadColorScheme("Resources/configs/Style.json");
    //Label LOADING...
    int centerX = float(framebuffer->GetSize().x) * 0.5f;
    int centerY = float(framebuffer->GetSize().y) * 0.5f;
    float labelHeight = float(framebuffer->GetSize().y) * 0.2f;
    loadingLabel = CreateLabel("LOADING", float(framebuffer->GetSize().x) * 0.05f, centerY - labelHeight * 0.5f, float(framebuffer->GetSize().x) * 0.95f, labelHeight, loadingUi->root, LABEL_CENTER | LABEL_MIDDLE);
    loadingLabel->SetFontScale(20);
    //Create ui camera
    loadingCamera = CreateCamera(loadingWorld, PROJECTION_ORTHOGRAPHIC);
    loadingCamera->SetPosition(centerX, centerY, 0);
    loadingCamera->SetRenderLayers(2);
    loadingCamera->SetClearMode(CLEAR_DEPTH);
    loadingCamera->SetLighting(false);
}

int main(int argc, const char* argv[])
{
    RegisterComponents();
    //Load FreeImage plugin (optional)
    auto fiplugin = LoadPlugin("Plugins/FITextureLoader");
    //Get the displays
    auto displays = GetDisplays();
    //Create a window
    window = CreateWindow("Ultra Engine", 0, 0, 1280 * displays[0]->scale, 720 * displays[0]->scale, displays[0], WINDOW_CENTER | WINDOW_TITLEBAR);
    //Create a framebuffer
    framebuffer = CreateFramebuffer(window);
    //Create a world
    world = CreateWorld();

    //Load a font
    auto font = LoadFont("Fonts/arial.ttf");

    //Create user interface
    ui = CreateInterface(world, font, framebuffer->GetSize());
    ui->SetRenderLayers(2);
    ui->root->SetColor(0.2f, 0.2f, 0.2f, 1.0f);
    ui->LoadColorScheme("Resources/configs/Style.json");

    //Create ui camera
    auto uiCamera = CreateCamera(world, PROJECTION_ORTHOGRAPHIC);
    uiCamera->SetPosition(float(framebuffer->GetSize().x) * 0.5f, float(framebuffer->GetSize().y) * 0.5f, 0);
    uiCamera->SetRenderLayers(2);
    uiCamera->SetClearMode(CLEAR_DEPTH);

    auto newGameButton = CreateButton("New game", 200, 125, 200, 50, ui->root);
    ListenEvent(EVENT_WIDGETACTION, newGameButton, newGameButtonCallback);

    auto exitButton = CreateButton("Exit", 200, 200, 200, 50, ui->root);
    ListenEvent(EVENT_WIDGETACTION, exitButton, exitButtonCallback);

    gameWorld = CreateWorld();
    gameWorld->RecordStats();

    loadingInit();

    shared_ptr<World> currentWorld = world;
    shared_ptr<Interface> currentUI = ui;

    while (window->Closed() == false)
    {
        if (!isMainMenuOn) currentWorld = gameWorld;     
        while (PeekEvent())
        {
            const Event ev = WaitEvent();
            switch (ev.id)
            {
            case EVENT_WINDOWCLOSE:
                if (ev.source == window)
                {
                    exit(0);
                    break;
                }
                break;
            default:
                currentUI->ProcessEvent(ev);
                break;
            }
        }
        currentWorld->Update();
        currentWorld->Render(framebuffer);
    }
    return 0;
}

 

[Josh]

1 hour ago, SpiderPig said:

I see, thanks.  Could the application go non responsive though?

The window event system is on the main thread, so it would stop processing events while the map is loading. However, the screen buffer would continue to refresh as the rendering thread runs.