ECS - Setting localToWorld doesn't update child entities positions.

Unity Engine
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1

How are you supposed to move a parent entity and have the child entities ‘follow’?

I’ve tried googling this but… I might be using the wrong terminology or something.

I’m working off the Boids example and this is what I’m currently doing.

localToWorld.Value = float4x4.TRS(
    new float3(localToWorld.Position + (nextHeading * MoveDistance)),
    quaternion.LookRotationSafe(nextHeading, math.up()),
    new float3(1.0f, 1.0f, 1.0f));
2

localToWorld has changed it is now really only for physics interpolation / graphics.

See Transform concepts | Entities | 1.0.16

2 Likes
3

Ah, so are we mostly working with the localTransform property now?

4

Yes

5

But how do you change the non-uniform scale if you shouldn’t use localToWorld?

ah, like this: How to scale a entity in a non uniform way?
magical hidden by default component, got it.

(the docs are very unclear what it is, "you may use a PostTransformScale (float3x3). This will be applied in the following manner: LocalToWorld = WorldTransform.ToMatrix() * PostTransformScale", had to search around a lot for usage and context; it didn’t even mention it’s a component or part of a component)

6

There is nothing hidden or magical. It’s clearly described in the documentation of entities package. If someone didn’t read docs, well… :slight_smile:

1 Like
7

Hi,

Do you have any idea how to scale a child of a parent entity in a non-uniform way?

entityManager.AddComponentData(productEntity, new LocalTransform { Position = localMatrix.position, Rotation = localMatrix.rotation});
entityManager.SetComponentData(productEntity, new PostTransformMatrix {Value = float4x4.Scale(localMatrix.scale) });

For example this generates a 0,0,0 LocalToWorld.

8

LocalTransform.Scale isn’t set in that code, so it will be 0.