Physics Bug when creating items

[martyj]

This is an update to a thread that I've already created on this subject.

 

Previously the cause was expected to be due to collisions in the self physics. I've since changed my model to have a cleaner physics.

 

Video shows two bugs.

 

 

1. Creating items will sometimes have them thrown off in a random direction. (Depends on players position). As seen in the video, when the same action is done in a different position of the map. The object falls as normal.

 

2. There's an unknown physics object stopping me from walking in a section of my map. I have no idea what it is. This one may be hard to produce.

 

Source code will be messaged to Josh after I finish compressing and uploading it.

[martyj]

I added a collision hook on this entity.

 

Video:

 

Code:

 

this->model = (Model*)Model::Load(item->GetModelPath())->Copy(true);
this->model->SetUserData(this);
this->model->AddHook(Entity::CollisionHook, ItemEntity::CollisionHook);
this->model->SetVelocity(Vec3(0, 0, 0), true);
this->model->SetCollisionType(Collision::Prop);
this->model->SetPhysicsMode(Entity::RigidBodyPhysics);
this->model->SetPickMode(WF_PICK_MODE, true);
this->model->SetMass(10); // TODO: real mass
this->model->SetSweptCollisionMode(true);
this->model->SetPosition(position, true);

 

Collision Hook

void ItemEntity::CollisionHook(Entity* entity0, Entity* entity1, float* position, float* normal, float speed)
{
System::Print("Collision");
System::Print(entity0->GetKeyValue("name"));
System::Print(entity1->GetKeyValue("name"));
printf("Posit(%f, %f, %f)\n", position[0], position[1], position[2]);
printf("Norm(%f, %f, %f)\n", normal[0], normal[1], normal[2]);
printf("Speed: %f\n", speed);
System::Print("EndCollision");
}

 

 

See attached file for console printing.

 

------------------

 

I removed everything from my map and tested a few other objects with different collision types.

 

 

Some things I've learned.

Polymesh doesn't have gravity.

Size matters if it is less than 0.5 feet.

 

Could this be a difference between float and double precision? I've scaled my object up to 5 feet and I still get the same weird collisions.

Collision.txt

[martyj]

Bump.

 

Does anyone have any recommendations for how to spawn items?

 

Is there some default collision type/physics type being set that could be causing this bug?

 

Thanks,

Marty

[Josh]

I need a file to test.

 

Your model needs a shape, either that gets loaded with it or one you create in code. No shape = no collision.

[martyj]

See your inbox for the project.

 

Here is the log entity in question.

 

Granted, there are a few other entities that have this same behavior as in the videos posted here:

 

See attachments for the models

oak2.FBX

oak2.mdl

oak.FBX

oak.mdl

[Josh]

Please provide instructions on exactly what I need to do to produce behavior that is not correct. I don't know which map to load, what to do, etc. Also please tell me where the script or CPP file is that controls the action in question.

[martyj]

Edit:

----------

 

Deleted. See post below on a smaller demo

[martyj]

Here is a clean version of a project.

 

http://martyj.net/DroppingLogs.7z

 

Keys: D1 = Drop oak.mdl

D2 = Drop oak2.mdl

[Josh]

In ItemEntity.cpp change this line:

this->model = (Model*)Model::Load(path)->Copy(true);

 

To this:

this->model = (Model*)Model::Load(path);

[Josh]

What's happening is you're creating two copies of the object and it causes them to shoot away from each other really fast.

[Josh]

You did uncover another bug. Cone shapes were not being rotated properly when the object was scaled.

[martyj]

What's happening is you're creating two copies of the object and it causes them to shoot away from each other really fast.

 

How do they collide if I only set the position of the cloned one? I believe you when this is happening. When I change the code to this, it also works.

Model* base = Model::Load(path);
 base->Hide();
 base->SetPosition(Vec3(-1, -1, -1), true);
 this->model = (Model*)base->Copy(true);
 this->model->Show();
 this->model->SetPosition(position, true);
 this->model->SetVelocity(Vec3(0, 0, 0), true);
 this->model->SetCollisionType(Collision::Prop);
 this->model->SetPhysicsMode(Entity::RigidBodyPhysics);
 this->model->SetPickMode(Entity::PolygonPick, true);
 this->model->SetMass(10); // TODO: real mass
 this->model->SetUserData(this);
 this->model->SetSweptCollisionMode(true);

 

The reason I need the cloned model is so that I can change the material on a single instance of the object to light it on fire.

 

Is there a better way to do this? I'm also doing something similar with trees, rocks, and NPCs as they all have a customized material.

[Josh]

WHen you load the model with the Asset::Unmanaged flag you can set a material without affecting other instances.

[Josh]

That is odd. If I use this code it works just fine. So why are they colliding?

 

    ItemEntity::ItemEntity(std::string path, Vec3 position)

{

Model* base = Model::Load(path, Asset::Unmanaged);

this->model = (Model*)base->Copy(true);

base->Release();

this->model->SetPosition(position, true);

this->model->SetVelocity(Vec3(0, 0, 0), true);

this->model->SetCollisionType(Collision::Prop);

this->model->SetPhysicsMode(Entity::RigidBodyPhysics);

this->model->SetPickMode(Entity::PolygonPick, true);

this->model->SetMass(10); // TODO: real mass

this->model->SetUserData(this);

this->model->SetSweptCollisionMode(true);

}

[Josh]

Okay, I found the cause. Good news, you are also not a crazy person. The specific setup you had would create a giant physics box in the middle of the map. I fixed it.