Greased line disposal not working as expected

Bugs
1

Hello, I’m a long time user of Babylon but first time poster here :waving_hand:

I am having some issues using greased lines in my project. I think I found a bug or at least unexpected behavior. Please point me in the right direction if this is not a bug.

Long story short, I am using greased lines in multiple different places in my project, and I use BABYLON.CreateGreasedLine to create the lines. Below is simplified version of what I’m trying to do. (You can find the link to the playground further below).

    const points1 = [-1, 0, 0, 1, 0, 0];
    const line1 = BABYLON.CreateGreasedLine("line1", { points: points1 }, {
        color: BABYLON.Color3.Red(),
        sizeAttenuation: true,
        width: 5,
        materialType: BABYLON.GreasedLineMeshMaterialType.MATERIAL_TYPE_SIMPLE,
    });

    const points2 = [-1, 1, 0, 1, 1, 0];
    const line2 = BABYLON.CreateGreasedLine("line2", { points: points2 }, {
        color: BABYLON.Color3.Green(),
        sizeAttenuation: true,
        width: 5,
        materialType: BABYLON.GreasedLineMeshMaterialType.MATERIAL_TYPE_SIMPLE,
    });

This all works fine, until I want to dispose one of the lines.
When I call line1.dispose() the line is disposed as expected. The material that was created for line1 is not disposed, this is also expected.
However, I want to dispose the material.
To dispose the material, we would need to do the following:

line1.dispose(/*doNotRecurse*/ false, /*disposeMaterialAndTextures*/ true)
// Or simply
line1.material.dispose()
line1.dispose()

When I do this, line2 also disappears. However, both the node and material for line2 can still be found in the Babylon inspector. I cannot find any linkage between the materials for line1 and line2 that would explain this.

Here is a minimal reproducible example playground: https://playground.babylonjs.com/#ME2NKI#6

At the start we have line1 (red) and line2 (green)

image
image828×532 24.9 KB

Pressing dispose line behaves as expected. The material for line1 is still there, and line2 is untouched.

image
image746×537 23.7 KB

Starting from scratch and pressing dispose line + material removes both lines, but the inspector shows that the node and material for line2 still exists.

image
image752×546 23.1 KB

I would expect line2 to still be rendered in this case.
Any help would be greatly appreciated :smiling_face:

2

Hello and welcome ! :slight_smile:

I had a look, and indeed I agree it seems to be a bug. Let’s ping @roland which is the guy behind the GreasedLine stuff. I just reviewed the source code and I think I found the issue :

  • The dispose function of the GreasedLineSimpleMaterial disposes the colorsTexture
  • The colorsTexture is common to both instances (which is weird :thinking: )
const m1 = line1.material;
const m2 = line2.material;
console.log(m1.colorsTexture === m2.colorsTexture);

This will return true while I think it should not.

Cloning the colorsTexture will solve the issue by the way :

But still, I think a fix is necessary on the source code side
@roland, I tried commenting the dispose line this._colorsTexture?.dispose(); it does solve the issue, but I think the fix should be about not having the same reference on both materials

For example, adding a .clone() on this line does work :

3

Hi @Thor! Welcome to the forum!

@Tricotou thanks for investigating :wink:

Actually, only BABYLON.GreasedLineMeshMaterialType.MATERIAL_TYPE_SIMPLE is affected by this bug. The issue lies in the material’s initialization code. The texture should only be created when the colors property is used during the line’s creation.

4