Adding geometry to model - speed issues

Adding geometry to model - speed issues

Postby thomthom » Sat Nov 28, 2009 8:17 pm

I'm working on a plugin that generates some pieces of geometry.

I did some timing tests and found that methods that added geometry to an entities collection slowed down more and more as when the number of entities in the entities collection grew.

Incidentally, while I was debugging something I had my script add each part of the mesh I was creating into a separate group. That was really fast. But when I switched to create all the geometry in the same context, the time it took increased significantly.

In my case I also found that using PolygonMesh to generate my geometry was about twice as quick, entities.add_faces_from_mesh also appears to suffer from decreasing time as more geometry is added.
In my case, creating one large PolygonMesh and adding to the model was 5 times slower than if I created a number of smaller PolygonMesh'es into their own groups.

So atm it seems: generate one single mesh and take the time penalty, or split the mesh into a number of groups and benefit from the speed - with the disadvantage of making lots of groups.


Anyone had some experience with this?
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Re: Adding geometry to model - speed issues

Postby fredo6 » Sat Nov 28, 2009 9:38 pm

Unfortunately, the time you gain when creating geometry in small groups is then lost when you explode the groups.

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Re: Adding geometry to model - speed issues

Postby thomthom » Sat Nov 28, 2009 10:18 pm

If I explode them afterwards. I might just have use for them in this instance. But generally speaking - is there any other tricks to use?
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Re: Adding geometry to model - speed issues

Postby TIG » Mon Nov 30, 2009 12:05 am

Garbage Collection
GC true
?
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 12:10 am

TIG wrote:Garbage Collection
GC true
?

:?:
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Re: Adding geometry to model - speed issues

Postby AdamB » Mon Nov 30, 2009 8:28 am

[Though Ruby's mark and sweep garbage collector is pretty ropey, its likely to be linear in time and probably account for a few percent of total execution time.]

I suspect the fundamental problem is that there is a method inside SU that is doing a linear search - ie start the beginning of a list and walk along until you find what you're looking for - and so the longer the list, the longer the time.

My 2 cents worth, I think Ruby is great for quick tweaks and scripting UI etc. But its simply not up for doing large amounts of "heavy lifting" - just too slow. I had a chance the other day of using Whaats ProfileBuilder; dead cool, but just insane delays as it builds geometry for each mouse click.

I'm coming to the conclusion that if you want to deal with whole models / large amounts of geometry, you really have to use the COM interface - unless I find out the 'linear search' is deep inside the SU proper... :-(
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 8:44 am

I was suspecting that it might be SU trying to intersect geometry with the model as it was added. Or maybe it's something to do with the inference engine.

But what I do fine somewhat odd is that the add_faces_from_mesh method also suffers rather badly. I'd hoped that method would be been more optimized.


Adam, what is this COM interface?
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Re: Adding geometry to model - speed issues

Postby TIG » Mon Nov 30, 2009 11:40 am

I meant GC.start which collects garbage from group making etc...
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 12:10 pm

TIG wrote:I meant GC.start which collects garbage from group making etc...

You use that after creating a group?

In my case here, it's creating geometry in a series of groups which is faster than adding all the geometry into the same context.
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Re: Adding geometry to model - speed issues

Postby TIG » Mon Nov 30, 2009 1:24 pm

thomthom wrote:
TIG wrote:I meant GC.start which collects garbage from group making etc...

You use that after creating a group?

In my case here, it's creating geometry in a series of groups which is faster than adding all the geometry into the same context.

GC.start is Jim's baby - built-in - As I understand it you start if before making the groups ?
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 1:33 pm

But making groups isn't the problem. In my case it's faster to create a few smaller groups than one big chunk of geometry. That's even when the geometry is generated as a PolygonMesh. The geometry is then added by a single .add_faces_from_mesh. The time it takes to add the mesh isn't linear to the amount of faces generated.
And making a PolygonMesh seem to be twice as fast as generating each face using .add_face - which comes really slow.
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Re: Adding geometry to model - speed issues

Postby AdamB » Mon Nov 30, 2009 2:40 pm

TIG wrote:
thomthom wrote:
TIG wrote:I meant GC.start which collects garbage from group making etc...

You use that after creating a group?

In my case here, it's creating geometry in a series of groups which is faster than adding all the geometry into the same context.

GC.start is Jim's baby - built-in - As I understand it you start if before making the groups ?


GC.start is Mr.Ruby's baby ;) . It gets called automatically (every 256 instructions) by the Ruby interpreter and you generally don't need to call it yourself unless you really know what your doing.

AdamB wrote:Adam, what is this COM interface?


Its a hateful, clunky and ultimately pointless way of calling C++ that was introduced by MS many years ago - and since largely abandoned in favour of regular OO solutions. My point isn't about COM, more about calling the SU API directly without using Ruby. AFAIK Google only provide a COM interface to their underlying C++ API.
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Re: Adding geometry to model - speed issues

Postby Jim » Mon Nov 30, 2009 2:44 pm

TIG wrote:GC.start is Jim's baby - built-in - As I understand it you start if before making the groups ?


I thought I learned of it on this forum!

I don't think it's the GC that's slowing adding geometry - more likely it is Sketchup looking to make faces and break overlapping geometry as geometry is either added or exploded. (pure conjecture.)
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Re: Adding geometry to model - speed issues

Postby Whaat » Mon Nov 30, 2009 2:57 pm

I don't think I've tested this on SU7 but on SU6, using the add_faces_from_mesh method was way faster than adding individual faces using the add_face method. I thought it was 3-4 times faster (but I don't remember for sure). Maybe they have tightened the gap between these method in SU7.1?

For a quick test, just use SDS. Normal operation using the add_faces_from_mesh method, but if you choose the 'copy materials' option, it uses the add_face method.
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 2:59 pm

Jim wrote:I don't think it's the GC that's slowing adding geometry - more likely it is Sketchup looking to make faces and break overlapping geometry as geometry is either added or exploded. (pure conjecture.)


That's what I was suspecting as well. Was hoping for different result with PolygonMesh - that's it's simple be inserted as-is. But seeing that we don't actually know what it is... ...just guessing. :/

But I take it there's no tricks hidden up in any sleeves?
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 3:01 pm

Whaat wrote:I don't think I've tested this on SU7 but on SU6, using the add_faces_from_mesh method was way faster than adding individual faces using the add_face method. I thought it was 3-4 times faster (but I don't remember for sure). Maybe they have tightened the gap between these method in SU7.1?

For a quick test, just use SDS. Normal operation using the add_faces_from_mesh method, but if you choose the 'copy materials' option, it uses the add_face method.

Yes - I find add_faces_from_mesh to be faster than add_face to be faster as well. But comparing the number of polygons in the mesh with the time it takes to add the geometry - time does not increase linearly. It does seem that the time relates to the number of entities already in the context you add to.
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Re: Adding geometry to model - speed issues

Postby AdamB » Mon Nov 30, 2009 3:04 pm

Jim wrote:
TIG wrote:GC.start is Jim's baby - built-in - As I understand it you start if before making the groups ?


I thought I learned of it on this forum!

I don't think it's the GC that's slowing adding geometry - more likely it is Sketchup looking to make faces and break overlapping geometry as geometry is either added or exploded. (pure conjecture.)


Try this:

def addfaces(ents = Sketchup.active_model.entities)

vertices = [Geom::Point3d.new(0,0,0), Geom::Point3d.new(1,0,0),Geom::Point3d.new(0,1,0)]

start = Time.new
1000.times do
ents.add_face vertices
end
puts "Same tris took #{(Time.new - start)}"

start = Time.new
1000.times do
ents.add_face vertices
vertices[0].z += 0.1
vertices[1].z += 0.1
vertices[2].z += 0.1
end
puts "different tris took #{(Time.new - start)}"


start = Time.new
1000.times do
ents.add_face vertices
vertices[0].z += 0.1
vertices[1].z += 0.1
vertices[2].z += 0.1
end
puts "more different tris took #{(Time.new - start)}"
end

addfaces


Firstly adds 1000 triangles using the same coordinates, secondly adds 1000 triangles with unique vertices, lastly adds another 1000 triangles with unique vertices. Shows a 10x difference in performance, yet the geometry engine will be constructing the topology in all cases - ie doing work.

This would seem to indicate its an insertion bottleneck - which is consistent with thomthom findings.

What does it mean? It means its a brick wall and adding geometry in SU is slow and there is nothing you can do about it.
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 3:07 pm

AdamB wrote:What does it mean? It means its a brick wall and adding geometry in SU is slow and there is nothing you can do about it.

:(
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 3:09 pm

I ran that script four times:

addfaces
Same tris took 0.05
different tris took 0.71
more different tris took 1.9
nil

addfaces
Same tris took 1.84
different tris took 1.68
more different tris took 1.87
nil

addfaces
Same tris took 1.85
different tris took 1.659
more different tris took 1.89
nil

addfaces
Same tris took 1.85
different tris took 1.69
more different tris took 1.86
nil


Didn't delete geometry in between.
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 3:11 pm

Moved the geometry slightly away from original position and ran three more tests:

addfaces
Same tris took 1.8
different tris took 2.64
more different tris took 4.13
nil

addfaces
Same tris took 3.62
different tris took 3.26
more different tris took 3.65
nil

addfaces
Same tris took 3.62
different tris took 3.26
more different tris took 3.68
nil
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Re: Adding geometry to model - speed issues

Postby TIG » Mon Nov 30, 2009 3:11 pm

How about entities.fill_from_mesh(...) rather than add_faces_from_mesh(..)
http://code.google.com/apis/sketchup/do ... _from_mesh
is that quicker ?
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 3:16 pm

I had a mad hope that Sketchup.break_edges = false might change something...

Sketchup.break_edges=false
false

addfaces
Same tris took 3.58
different tris took 5.62
more different tris took 7.56
nil

Sketchup.break_edges=true
true


nope!



TIG wrote:How about entities.fill_from_mesh(...) rather than add_faces_from_mesh(..)
http://code.google.com/apis/sketchup/do ... _from_mesh
is that quicker ?

oooh. I've missed that method. Will give it a wirl when I get home. That even has a number of features which saves me some work when it comes to smooth vs faceted. :thumb:
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Re: Adding geometry to model - speed issues

Postby Whaat » Mon Nov 30, 2009 3:34 pm

TIG wrote:How about entities.fill_from_mesh(...) rather than add_faces_from_mesh(..)
http://code.google.com/apis/sketchup/do ... _from_mesh
is that quicker ?

I wasn't aware of this method! Has it really been available since SU6??
Someone, please do a performance test of this method now! (I would if I could.... :( )
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Last edited by Whaat on Mon Nov 30, 2009 3:37 pm, edited 1 time in total.

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Re: Adding geometry to model - speed issues

Postby Jim » Mon Nov 30, 2009 3:35 pm

Whaat wrote:I wasn't aware of this method! Has it really been available since SU6??


Me either. I thought I knew the API up and down (I act like, sometimes!) Makes me wonder what else is in there.

edit - maybe it was always "there", just not documented until the new automatic document system started?
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 3:43 pm

Whaat wrote:
TIG wrote:How about entities.fill_from_mesh(...) rather than add_faces_from_mesh(..)
http://code.google.com/apis/sketchup/do ... _from_mesh
is that quicker ?

I wasn't aware of this method! Has it really been available since SU6??
Someone, please do a performance test of this method now! (I would if I could.... :( )

I tried it in SU6 - it's there al'right. I will try in SU5 later today.

I think I've overlooked it because I've never used PolygonMeshes before.
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 3:45 pm

The old documentation doesn't seem to mention it: http://download.sketchup.com/OnlineDoc/ ... ities.html

Maybe it was added in the November update of the docs.
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Re: Adding geometry to model - speed issues

Postby Whaat » Mon Nov 30, 2009 4:05 pm

thomthom wrote:The old documentation doesn't seem to mention it: http://download.sketchup.com/OnlineDoc/ ... ities.html

Maybe it was added in the November update of the docs.

Sometimes I just want to slap whoever was responsible for the API docs...however, right now, I want to kick them in the junk.
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 4:11 pm

Come to think of it - I do remember reading somewhere about PolygonMesh'es being added without error control and being somewhat quicker. But since I previously had no interests in PolygonMeshes I didn't pay much attention. Assumed there was only one method to add a mesh.
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 5:12 pm

fill_from_mesh exists in SU5 as well.
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Re: Adding geometry to model - speed issues

Postby thomthom » Mon Nov 30, 2009 6:01 pm

fill_from_mesh seems to be twice as fast as add_faces_from_mesh.
But its default values doesn't match with the manual. The manual claims that the default for smooth is 0. But when I omit that value I get a soft and smooth mesh. I have to explicitly set it to 0 for no smoothing.

And I can't make out what the weld vertices do. I don't see any difference in what it produces.
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