Sketchup 2019 & SUTextureWriter generate too many textures!

[MootoolsSoftware]

SketchUp API 2019-0-753
Windows 10 O/S

Hello !

Update #1: As I wonder if the problem came from my code and the way I export textures, I dig further and find that in some circumstances the number of exported materials explode. I post a simple step by step procedure that allows to reproduce the problem under Sketchup 2017 with Sketchup collada exported.

https://forums.sketchup.com/t/sketchup-generates-too-many-textures/90653

Original post:
I am dealing with a very simple sketchup file and I am suspecting a bad bug in Sketchup 2019.

Here is the way the file join to this mail has been created created:

• I create a face and apply a brick texture.
• I make a distortion on the texture using Texture > Position
• I then duplicate the face 4 times.

So this should be the same face using the same internal representation texture.

But...
Using the SDK and traversing the 4 faces I get one material and 4 different texture IDs (using SUTextureWriterLoadFace)
When extracting the texture, I got 4 very similar files (same dimension and nearly same content, but not exactly the same).

I can't figure out why Sketchup is using internally 4 different images (I guess that internally there is 4 SUImageRepRef allocated with there image buffer).
It seems to be a huge waste of memory and performance.
Is it a normal behavior or I do miss something?

Thanks !
Manuel

Note: SDK methods used to extract textures

SUTextureWriterLoadFace(textureWriter, suface,&frontTextureID, &backTextureID);
SUTextureWriterWriteTexture(textureWriter, frontTextureID, texturePath, false);

4 duplicated faces with same texture distortion.zip

[thomthom]

Is this a question or a bug report?

[thomthom]

The conversation appear to be going on the forum. Closing this for now. We'll reopen if there's any more information.

[MootoolsSoftware]

Hi Thomthom,

This is a bug !

As we made duplication of the face, I think that we must receive the same material / texture id for each face and - as so - save only one material in the texture helper.
But things go differently, we receive 4 id and save 4 materials that are identical.
I suppose that there is a way - on your side - to check that a given transformation has already be used for a given material making possible to get one an only one ID.

From my point of view, this is definitively a bug report.
The following example is done with 4 faces, but imagine I duplicate the face 1000 times ! I will get 1000 identical bitmap files.

Note that this is not an implementation problem : I also get 4 bitmap using collada built in exporter, as shown here:

4 duplicated faces.zip

Thanks for any suggestion to solve the problem and get a single bitmap !

Thanks,
Manuel

[thomthom]

I think I'll mark this up as an "improvement". As it appear the original intent for the texture writer was to just create affine textures for faces with non-affine mapping. If there's been code that attempted to de-duplicate similar mapping on similar faces I think I'd agree on it being a bug. But mostly that's just semantics - reducing the number of generated textures sounds like a good thing to me.

[MootoolsSoftware]

I believe that would be a real improvement for exporting purpose.
On the above case the only way I found to reduce down the texture is to make a comparison between image files which require a lot of time.
Thanks for taking care!

[thomthom]

Yea, I don't know how easy it will be to find a way to de-duplicate this. But the number of textures generates comes up often enough that I think it at least warrants a research. My concern is being able to find a reliable solution.

In your experience, how often have you run into models with identical non-affine texture mapping on identical faces? As this would be the only scenario where textures could be de-duped.

[Xinned]

It's still happening with Sketchup 2020!

https://discourse-cloud-file-uploads.s3.dualstack.us-west-2.amazonaws.com/sketchup/original/3X/c/c/ccaa7394f365bbd6c76312fcda8d503ecfef5377.png

There was no fix in the newer version!