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Problem with mesh physics


WhiteRock Darkstone
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Hi all, I've created my first mesh building and I'm having a problem with the physics of it. It's a stage which you can see HERE.

As you can see in the image, the stage is open, except for the roof and two shallow walls on either side. When I upload the file (exported as a COLLADA file from Sketchup 2017) I upload the same file as the physics object. But, when I rez it, I can't get the avatar to walk up on to the stage. It's being blockes by an invisible physical barrier, somehow. I can get the avatar to the top step only, and not beyond it. The same thing happens if I try to enter the stage from the sides. 

I tried the same thing without uploading a physics file and just High in the level of detail, and the same thing happens. :/

I'd be happy to transfer a copy to you inworld if you want to take a look to see what I mean. I'm totally stumped and I'm hoping someone can help me figure this out.

Many thanks!

WR

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Thanks for the reply. That partially helped. Now I can get past the last step on the stage, but, there is still an invisible angle in there. If I walk towards the back, it angles up. HERE is another screenshot that shows my avatar looking like it's floating. The angle goes up from the stage entrance to the back. Any thoughts on that? Thanks so much!

WR

 

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The uploader most likely couldn't figure out what to do with your "physics model". You normally don't use the same build as your physics model, you make a very simple model that follows the general lines of your build and use that. While it isn't the best way by far, you might try uploading with physics set to "high" rather than a physics model. With very simple buids this works fairly well. Again though definitely not end game for physics models.

 

There are lots of threads on how to make physics models for house in these forums. Typing in things like "can't walk in front door" or "house physics" will probably get you to some. 

 

Here is a screenshot from my Google Plus feed to give you and idea. Quadrilaterals should not TOUCH edges.

 

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Hi :)

When creating, uploading  and assigning a physics mesh for a model that needs accurate collision surfaces there are a couple of basic rules that have to be complied with. Can you confirm that you have followed Rule 1?

Rule 1 :  Each visual mesh object has to have its own physics mesh.

 When rezzed in world is your mesh building  a single mesh object or a linkset of 2 or more separate objects ?              

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Ok, I don't know how to attach a file to a post (maybe you just can't do that), so here is a Dropbox link to the dae file.

https://www.dropbox.com/s/cyh0q1a2wh7ct72/Stage1.dae?dl=0

It seems to me that the problem isn't with the sketch but something is happening during the upload to SL. But, being the novice that I am, I will leave that to the experts to determine. :)

I look forward to hearing your diagnosis! 

WR

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If in doubt use the official SL viewer :)

 

I uploaded your .dae file  and used the high lod mesh for Physics and then Analyzed the physics mesh.

When rezzed I set the Physics shape Type to prim.

Surprisingly the physics seemed to be working fine  !

The number one problem I found was that it was being uploaded as a linkset of 20 objects.

I coloured each one a different colour for you to see better :

 

and an exploded view :

 

I suggest you find out why this "single " object is getting split into 20 objects when you export as Collada and fix that.

You are not the first person to have this happen when using sketchup and not going to like this but ........ I suggest you learn a little Blender :smileysurprised:

I'm going to try opening your .dae in Blender to see how it looks there ............

 

 

 

 

 

 

 

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Well, I uploaded it using the SL browser and, walla, after changing it to a prim, it's working fine! So, the second issue I was having was because the Singularity browser wasn't processing it correctly, apparently.

Thank you so much for your help! I truly appreciate it! Now, on to my next mesh build! Feel free to say hi inworld. Have a great day!

WR

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Just a comment as I have never used Sketchup but when I was at Cloud Party they were just adding it to the list of supported 3D software uploads. Apparently they had to jump through some hoops as while it exports a dae file it doesn't export it as other 3D software.  They had to turn on "double sided" as the default in the uploader for some reason raising everyone else's mesh by a factor of 2 until we learned how to turn that off :D.     

 

So all DAEs are apparently not equal. 

 

Another question which we may never know the answer to is  --  "was the model fine in the LL viewer or was uploading it with the LL the answer to make it also work in Singularity?" I couldn't tell that from the post anyway.

 

 

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Not sure ifthis is going to be of any help to you or not but the following explains how to import and join all the parts into a single Object in blender:

Blender > File > Import > select the stage1.dae

With everything selected ( A  key toggles select everything or nothing) :

Ctrl + A > Apply Rotation and Scale

 

Still with everythinbg selected :

Ctrl + J will join all the parts into a single Object.

 

Next you can delete that camara thing:

 

Now that all the parts are joined to be a single mesh Object it has 9 materials. You really don't want to be uploading mesh objects with more than 8 materials otherwise bad things will happen:

 

I know its easy for me to suggest that you move to Blener but if you can do this and put up with the pain, after a few weeks you will realise how much more Blender has to offer when it comes to creating low poly models for use in SL.

 

 

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Just to add to Aquila's post - one of the 9 materials here is actually only on the back and bottom of the steps. Both these surfaces are hidden and will never be rendered (unless you turn the whole thing upside-down). So you can safely delete these faces, and then you have only the permitted eight. (SL will now import objects with more than eight materials, but it does so by splitting them into multiple objects).

More generally, we have known for a long time that Sketchup works in ways that are very problematic for mesh imported to SL. One of the major problems is that it splits things into many small objects as you see here. While it is just about useable for a simple mesh like this, the problems become very serious for more complicated objects. In particular, the splitting up leads to inefficiencies that are punsihed by high Land Impact. It will also lead to problematic LOD behaviour (changes in appearance as you zoom out). So I would very strongly second Aquila's suggestion that you would do well to invest some time learning Blender instead.

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WhiteRock Darkstone wrote:

Thanks, I will definitely look into Blender!

Yes you should. SketchUp is really not suitable for 3D modelling for a virtual environment. Don't get me wrong, SketchUp is a great program but you're trying to use it for something it was never ever intended to do.

One of the problems is the one Aquila pointed out, SketchUp exports each single surface as a separate mesh. The two advantages mesh has over prims is that you can make more complex shapes with mesh and you can save land impact by reducing the number of parts in a linkset. In this particular case you could have made exactly the same model from 12 prims that SketchUp used 20 meshes for.

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Aquila Kytori wrote:

I suggest you find out why this "single " object is getting split into 20 objects when you export as Collada and fix that.

I mentioned that in my previous post but it's a rather important question so to make it absolutely clear, that's how SketchUp does it and the fix is to not use SketchUp. SketchUp only supports single material meshes and it also splits disjoined faces with the same material into separate meshes.

I know somebody once made a Second Life mesh plugin for SketchUp but as far as I know it just attempts to clean out a few of the excessive vetices and polys SketchUp adds. I may be wrong there but I don't think the plugin fixes the disjoined meshes problem and it certainly doesn't solve all the countless problems with SketchUp meshes in SL.

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As one who has recently started from scratch to learn modelling using blender, I want to encourage you to take the good advice here.  But you need to be prepared for a steep learning curve.  Blender can do everything (I think there is even a way for it to make tea while you are working, but I didn't find that yet :matte-motes-big-grin:) but this comprehensiveness comes at the price of complexity.

What I did was to follow some tutorials.  Up to now, I have played them on my tablet, while I try to copy them on the desktop,  this works well, but I have now invested in a second monitor so I can work on one, and watch on the other.  The other hint I give is to learn to ask Google:  'Blender Join 2 faces'  type questions, you will need to do it frequently.

But in the end it's worth it!

Another approach, for people who just can't get their mind round Blender (or Maja etc...)  is to build everything in prims in SL, or better still Aditi (the SL Beta Grid), and then use a prim to mesh converter.  My partner does this to great effect for buildings. This is the one she uses.

Before she found the converter, we used to export her linksets as collada (dae files) import them into Blender, decimate each prim a bit, join the the prims, and export a new, hopefully simpler and lower Land-Impact mesh.  Trial and error seemed to get us a way forward.

But Blender from scratch is by far and away the best way to go.

 

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