2nd World Physics Random Crash

[SpiderPig]

I'm getting random crashes with this code.  Physics in two worlds not supported?

#include "UltraEngine.h"

using namespace UltraEngine;

Vec3 mousepos = Vec3(0.0f);
float move_adjustment = 0.1f;
float move_speed = 1.0f;
float lookspeed = 0.1f;
float looksmoothing = 0.5f;
bool enable_camera = true;

int main(int argc, const char* argv[])
{
    auto displays = GetDisplays();
    auto window = CreateWindow("Ultra Engine", 0, 0, 1280, 720, displays[0], WINDOW_CENTER | WINDOW_TITLEBAR);
    auto world = CreateWorld();
    auto framebuffer = CreateFramebuffer(window);

    auto camera = CreateCamera(world);
    camera->SetClearColor(0.125);
    camera->SetFov(70);
    camera->SetPosition(0, 10, -5);

    auto light = CreateDirectionalLight(world);
    light->SetRotation(35, 45, 0);

    auto floor = CreateBox(world, 10.0f, 0.1f, 10.0f);
    floor->SetPosition(0.0f, -3.0f, 0.0f);
    floor->SetMaterial(LoadMaterial("Materials\\Developer\\bluegrid.mat"));

    auto box = CreateBox(world);
    box->SetCollider(nullptr);
    box->SetPosition(2.0f, 2.0f, 0.0f);

    auto player = CreateCylinder(world);
    player->SetPhysicsMode(PHYSICS_PLAYER);
    player->SetPosition(0.0f, 5.0f, 0.0f);
    player->SetMass(1.0f);

    auto cam_pivot = CreatePivot(world);
    cam_pivot->SetParent(player);
    cam_pivot->SetPosition(0.0f, 1.8f, 0.0f);

    camera->SetParent(cam_pivot);
    camera->SetPosition(0.0f, 0.0f, -3.0f);
    camera->SetDebugPhysicsMode(true);

    auto world_2 = CreateWorld();
    auto f2 = CreateBox(world_2, 10.0f, 0.1f, 10.0f);

    auto b2 = CreateBox(world_2);
    b2->SetMass(1.0f);
    b2->SetPosition(2.0f, 10.0f, 0.0f);

    bool stage = 0;
    while (window->Closed() == false and window->KeyDown(KEY_ESCAPE) == false)
    {
        if (window->KeyHit(KEY_F2) == true) { camera->SetWireframe(!camera->GetWireframe()); }
        if (window->KeyHit(KEY_F3) == true) { camera->SetDebugPhysicsMode(!camera->GetDebugPhysicsMode()); }
        if (window->KeyHit(KEY_F4) == true) { enable_camera = !enable_camera; }

        if (enable_camera) {
            auto _displaySize = window->GetSize();
            float cx = Round((float)_displaySize.x / 2.0f);
            float cy = Round((float)_displaySize.y / 2.0f);

            auto mpos = Vec3(window->GetMousePosition().x, window->GetMousePosition().y, window->GetMousePosition().z);
            window->SetMousePosition(cx, cy);
            mpos = mpos * looksmoothing + mousepos * (1 - looksmoothing);
            auto dx = (mpos.x - cx) * lookspeed;
            auto dy = (mpos.y - cy) * lookspeed;


            auto camrot = cam_pivot->GetRotation();
            camrot.x += dy;
            camrot.y += dx;
            cam_pivot->SetRotation(camrot);
            mousepos = mpos;
        }

        world_2->Update();
      
        world->Update();
        world->Render(framebuffer);
    }
    return 0;
}

 

[reepblue]

I've ran into physics totally not working in my second world but it never crash. I haven't tried the recent builds yet.

[SpiderPig]

It seems to be working nicely now if I update world_2 before the main loop.  Physics seems to be working in a 2nd world now.  I'm about to update my other post..

 

[Josh]

 

I never thought about it, but this is really bad to do. You've got non-thread-safe Newton calls running on two separate threads at the same time when you do that.

I added this information to the docs:
https://github.com/UltraEngine/Documentation/blob/master/CPP/World_Update.md#remarks

[reepblue]

7 minutes ago, Josh said:

I never thought about it, but this is really bad to do. You've got non-thread-safe Newton calls running on two separate threads at the same time when you do that.

I added this information to the docs:
https://github.com/UltraEngine/Documentation/blob/master/CPP/World_Update.md#remarks

Ahh, should we only be updating one world at a time or just update A world all the time? This maybe why I'm getting issues with the physics just not working.

[Josh]

Only call World::Update on one world in your application, ever.

[reepblue]

6 minutes ago, Josh said:

Only call World::Update on one world in your application, ever.

Ok, will fix my code with this advice.

I also recommend making the update function static so future users don't do the same thing. Maybe turn it into a UpdateWorlds() function? 

[Josh]

I am adding a check to throw an error if more than one world uses this command..

If I moved all the Newton collider code into the main thread, than multiple worlds updating simultaneously would probably work. Maybe in the future I will do this. (Assuming the recast pathfinding code is also thread-safe.)

[SpiderPig]

Good to know, thanks.  Just checking... latest update is not throwing any errors when I update a 2nd world?

[Josh]

Right you are. I needed to make the last updated world a static variable. 

[SpiderPig]

If we didn't have any physics objects in the main world and only in a 2nd world, would it still be an issue?

[Josh]

Maybe? I don't recommend it!

[SpiderPig]

Okay   Thankyou.

[reepblue]

Looks like I need to make sure I'm initializing my game world first and my menu world last.

[Josh]

Why would your menu world need to call World::Update()?

[SpiderPig]

Is it needed for animations?

[SpiderPig]

I think it'll also be needed for moving and turning entities...

[Josh]

46 minutes ago, SpiderPig said:

I think it'll also be needed for moving and turning entities...

Not if these are moved each frame, but you are right the Component::Update call won't be made without it.

You can initialize a world with no physics engine. There is an optional parameter in the CreateWorld() function for this.

[SpiderPig]

8 hours ago, Josh said:

You can initialize a world with no physics engine. There is an optional parameter in the CreateWorld() function for this.

That argument seems commented out at the moment.

[Josh]

I'm going to try adding a mutex in the collider Newton shape creation function. That is where this is happening. I think the whole thing will be thread-safe with that change.

I generally do not like to use mutexes and prefer total separation of data, but in this case it makes sense.

[Josh]

Your example above works correctly now.