Mesh.getAbsolutePosition

[binyan]

In this example I set a parent to the ground and then rotate it. I would expect that the absolute position of the ground would change but it doesn't... The weirder thing is that getAbsolutePosition returns always the same vector - the vector it returned first time I called it. For instance in this example the absolute position does change according to the rotation but after I get an absolute position for the first time it doesn't change.

Am I missing something?

[GameMonetize]

This is because there is no rendering at that time. If you want babylon.js to update this value, you have to force a complete matrix evaluation through ground.computeWorldMatrix(true);

[binyan]

Thanks, Deltakosh. Checked it out and it works now. Just a little correction - I should force the both world matrices evaluation (the parent's one and the child's one). Otherwise it doesn't work.

If I understood well it will be automatically evaluated if this code will run in rendering loop, right?

[GameMonetize]

Correct

[Srisub]

I ran into the same problem where i am trying to get the absolute position (or more generally, the world matrix components) of a mesh deep down in the hierarchy of a scene *before* any rendering happens. Seems like what i need to do is to go up the hierarchy and do computeWorldMatrix(true) for each mesh in the ancestry as well.

Deltakosh, might be worthwhile to consider a scene.computeWorldMatrixForAllMeshes (force)

[GameMonetize]

you can just do mesh.computeWorldMatrix(true) and babylon.js will go up the hierarchy for you

[Srisub]

Here's some code i wrote to make sure that the world matrix is up-to-date (outside of rendering loop). Both these seem like nice utilities to add to BJS classes. I am new, so passing on code for now..

 

/* Get a node's parent hierarchy */
getHierarchy: function ( node, includeThis ) {
    var hierarchy = [];
    if ( includeThis )
        hierarchy.push( node );
    var item = node.parent;
    while ( item ) {
        hierarchy.push( item );
        item = item.parent;
    }

    return hierarchy;
}
,

/* Compute world matrix for node and its parent hierarchy */
computeWorldMatrix: function ( node, force, hierarchy ) {

    if ( hierarchy ) {
        var nodes = this.getHierarchy( node );
        for ( var n=nodes.length-1; n >= 0; n-- )
            nodes[n].computeWorldMatrix( force );
    }

    node.computeWorldMatrix( force );
}

[GameMonetize]

No need for this. This is already done

[Srisub]

Note that i had to do this only because i was trying to get the world matrix of a mesh deep down in hierarchy BEFORE any rendering starts. (Wanted to set the camera position/rotation to that of the "eye" of the avatar). When i didnt do computeWorldMatrix(force) for the hierarchy, it was only returning the local matrix. After i did the above code, it worked.

[GameMonetize]

This should not be the case

do you mind sharing the bug in the playground?

[Numa]

Has this bug been fixed? I'm getting some strange results when swapping parents/children around in a big hierarchy.

[GameMonetize]

As far as I'm concerned no one provided a repro case so far

[mirco]

Hi, sorry for bumping up this old thread, but I think its not finished yet.

I have the same problem like Srisub. It occurs when I use computeWorldMatrix(true) inside the createScene function ( not in the runRenderLoop ). 

The result of the computeWorldMatrix looks wrong ( expect  {X:3 Y:1 Z:0}, but get {X:1 Y:0 Z:0} )

If I use the code from Srisub it works.

 

Here is a Playground where I can reproduce the problem.

http://www.babylonjs-playground.com/index.html#1HMKOS#3

@Deltakosh maybe you can have a look on it

[GameMonetize]

@adam found the issue

It should be fixed now (clear your cache and run your PG again)

[mirco]

thank you, works fine