[Plugin] triangulateFaces.rb v1.2 20101120

TIG

I have some thoughts...
The original face's mesh has a number of points - 3 or more.
A texture usually has 3 uvs 'points'.
A distorted texture has 4 uvs 'points'.
How do these uvs 'points' relate to the mesh points ? If you give them the equivalent 'index' then they'll work until index=3...
A face made from the mesh always has 3 points, these relate to the mesh points in sets of 3 - but how do these tie back to the texture uvs 'points' ? The fourth one index=3 fails ???
How do we make an array to place the material that has this fourth pair of a 3D point and a uvs 'point' ? It must reflect the 'extra point' somehow ??

I shall sleep on it and see if the little-grey-cells come up with anything...

thomthom

For my UV plugins I have used the UVHelper to sample the points. What I did then was sample four points of the face's place - completely ignoring the face's vertices.

Maybe, for each face that's turned into a PolygonMesh, sample four points of the front and back. Then once converted into PolygonMesh, apply the sampled UV points to each of the polygon faces. That should work. All the created polygon faces are still on the old face's plane.

TIG

More ideas... let me sleep... zzzzzzzzzzzzz x

TIG

def triangulateFace(face)
### if already a triangle leave alone...
 if face.vertices[3]
  mesh=face.mesh(3)
  ents=face.parent.entities
  mat=face.material
  bac=face.back_material
  ###
  p0=face.vertices[0].position
  p1=face.vertices[1].position
  p2=face.vertices[2].position
  p3=face.vertices[3].position
  ### get uvs
  tw=Sketchup.create_texture_writer
  uv_helperF=face.get_UVHelper(true,false,tw)
  uv_helperB=face.get_UVHelper(false,true,tw)
  uf0=uv_helperF.get_front_UVQ(p0)
  uf1=uv_helperF.get_front_UVQ(p1)
  uf2=uv_helperF.get_front_UVQ(p2)
  uf3=uv_helperF.get_front_UVQ(p3)
  ub0=uv_helperB.get_back_UVQ(p0)
  ub1=uv_helperB.get_back_UVQ(p1)
  ub2=uv_helperB.get_back_UVQ(p2)
  ub3=uv_helperB.get_back_UVQ(p3)
  ###
  grp=ents.add_group
  grp.entities.add_faces_from_mesh(mesh)
  grp.entities.each{|e|
    if e.class==Sketchup;;Edge
      e.smooth=false
      e.soft=false     
    elsif e.class==Sketchup;;Face
      if mat
        e.position_material(mat,[p0,uf0, p1,uf1, p2,uf2, p3,uf3], true)
      end#if
      if bac
        e.position_material(bac,[p0,ub0, p1,ub1, p2,ub2, p3,ub3], false)
      end#if
    end#if
  }
  face.erase!
  grp.explode
 end#if
end#def

Seems to me that this should work... but it doesn't - Thomthom, any ideas

thomthom


def triangulateFace(face)
### if already a triangle leave alone...
if face.vertices[3]
  mesh=face.mesh(3)
  ents=face.parent.entities
  mat=face.material
  bac=face.back_material
  ###
	# (TT)
	# Instead sampling vertices we sample points of the face's plane.
	# This is because we need four points, and some times a face only has tree vertices.
	# And we also get the wrong result if any of the first four vertices are co-linear.
	samples = []
	samples << face.vertices[0].position			 # 0,0 | Origin
	samples << samples[0].offset(face.normal.axes.x) # 1,0 | Offset Origin in X
	samples << samples[0].offset(face.normal.axes.y) # 0,1 | Offset Origin in Y
	samples << samples[1].offset(face.normal.axes.y) # 1,1 | Offset X in Y
  ### get uvs
  tw=Sketchup.create_texture_writer
	# (TT)
	uv_helper=face.get_UVHelper(true,true,tw) # (TT) Only need one UV Helper
	xyz = []
	uv_f = []
	uv_b = []
	samples.each { |position|
		# XYZ 3D coordinates
		xyz << position
		# UV 2D coordinates
		# Front
		uvq = uv_helper.get_front_UVQ(position)
		uv_f << flattenUVQ(uvq)
		# Back
		uvq = uv_helper.get_back_UVQ(position)
		uv_b << flattenUVQ(uvq)
	}
  ###
  grp=ents.add_group
  grp.entities.fill_from_mesh(mesh, true, 0) # (TT) Adds the mesh without soft/smooth edges. (and faster)
  grp.entities.each{|e|
    next unless e.class==Sketchup;;Face
      if mat
		# (TT)
		# Position texture.
		pts = []
		(0..3).each { |i|
			pts << xyz[i]
			pts << uv_f[i]
		}
        e.position_material(mat,pts, true)
      end#if
      if bac
		# (TT)
		# Position texture.
		pts = []
		(0..3).each { |i|
			pts << xyz[i]
			pts << uv_b[i]
		}
        e.position_material(bac,pts, false)
      end#if
  }
  face.erase!
  grp.explode
end#if
end#def
# (TT)
# Get UV coordinates from UVQ matrix.
def flattenUVQ(uvq)
	return Geom;;Point3d.new(uvq.x / uvq.z, uvq.y / uvq.z, 1.0)
end

TIG

Thanks to CPhillips's inciteful ideas I have now made a 'joint' script called 'triangulateFaces.rb' which is attached. It uses CPhillips's triangulateFace(face) code [with a slight TIG addition for back_materials] and the TIG Plugin triangulateFaces(face_array)...
Originally 2009 (c) CPhillips* then (c) TIG** THEN (c) ThomThom ***
Script: triangulateFaces.rb
Code Usage: triangulateFace(face)*
Result: it triangulates a face... all Texture UVs are kept.
Plugin Usage: triangulateFaces(faces_array)**
Result: it triangulates faces in a selection...
v1.0
First Release: Def Code 'mesh' idea by CPhillips*,
retained back_materials added by TIG [failed] ###,
Plugin parts by TIG**. 20090729
v1.1
Rewritten entirely by TIG... THEN completely corrected by Thomthom (TT)!***
It now retains all Texture mapping successfully. 20091203
v1.2
Triangulated faces with 4 sides glitch fixed using intersection.
Get the latest version from here http://sketchucation.com/pluginstore?pln=triangulateFaces

TIG

Here's v1.1 http://forums.sketchucation.com/viewtopic.php?p=175613#p175613

Thanks to Thomtom's knowledge of uvs mapping etc it now successfully triangulates any face [even with holes like Swiss Cheese] and keeps the front AND back uv texture mapping as it was ! Thanks!

Gaieus

Hi TIG,

Would it be possible for the plugin to triangulate faces with a more "even" or "regular" triangles? After this topic, I thought maybe pre-triangulating the face on the ramp would spare some extra hand-work but it seems that the plugin triangulates the faces just exactly the same way native SU does when autofolding.

TriangulateFaces.skp

TIG

@gaieus said:

Hi TIG,
Would it be possible for the plugin to triangulate faces with a more "even" or "regular" triangles? After this topic, I thought maybe pre-triangulating the face on the ramp would spare some extra hand-work but it seems that the plugin triangulates the faces just exactly the same way native SU does when autofolding.

TriangulateFaces uses the built-in SUp mesh making methods, which presumably match the auto-fold ones, hence the similarity.
You might have noticed that my ExtendEdgesByRails script does produce a neat set of faces as that can't use the mesh methods directly but has to make up its own...
Using EEbyRails is a MUCH simpler way of making a curved ramp - I've attached an example...EEbyRailsSimpleRamp.skp

Gaieus

Thanks TIG for the examples - although my question was more a bit "academical" and theoretical - but at least I know why the two meshes are similar.

Certainly the other twoo tools are also great and would probably fit more to this particular need - that moving of the face was just so simple method - too bad autofold screws it up.

thomthom

@gaieus said:

Certainly the other twoo tools are also great and would probably fit more to this particular need - that moving of the face was just so simple method - too bad autofold screws it up.

This triangulation would be a separate plugin. It's just too specific. But I've been thinking of this myself. I often find I want such partitioning. It seems that it's usually long strip of a face where two of the sides runs parallel-ish to each other. So you want an edge to go between each opposite vertex. I've had it on my list of things to do - just not got around to it yet.

alz

Yeah, I agree -- having a more uniform triangulation method is preferred. It makes things a lot easier developing models if it's more uniformed and less "meet all at one point".

With the current method, I have to spend time flip-flopping various divisions (and sometimes just recutting the face).

Woz2007

@tig said:

###,
Plugin parts by TIG**. 20090729
v1.1
Rewritten entirely by TIG... THEN completely corrected by Thomthom (TT)!***
It now retains all Texture mapping successfully. 20091203

[attachment=0:kz9i3jbr]triangulateFaces.rb[/attachment:kz9i3jbr]

Im using this & seeing the UV mapping failing...is this the latest version?!

thomthom

Got a sample of where it fails?

Woz2007

@thomthom said:

Got a sample of where it fails?

If you look at the texture in the tringle before & after you will see that it is affected. When I export the model as a mesh the surface is indeed messed up.

I hope the image is enough to work from?!
Thnaks for looking into this. This script could save me a lot of hassle if working correctly

before & after shot

thomthom

hmm...? Are you using Sandbox tools to modify the geometry afterwards?

Woz2007

Yes.
Should I be using an alternative?!

thomthom

That is causing the UV to distort, not the triangulation.
The flip function in sandbox doesn't preserve UV mapping when flipping.

Gaieus

@thomthom said:

The flip function in sandbox doesn't preserve UV mapping when flipping.

Sorry Woz; that was my suggestion I know...

Thom; any other idea? Rewriting the sandbox tools for instance?

(Or maybe some vertex edit tools?)

Woz2007

@gaieus said:

Sorry Woz; that was my suggestion I know...

No worries Gaeius Im grateful for whatever help I can get

I should really introduce myself & what Im trying to achieve.
So Im a hobby artist that fell upon Sketchup back in version 3. Ive found it to be the most user friendly UI for quickly pulling a model together albeit somewhat quirky. Ive tried other apps like 3DSM, Maya, Lightwave etc & those intefaces are just too over complex for simple modelling. PLUS they come with extreme pricetags. SU for me was a happy medium.
The models Im creating are for use with the Unreal 2.5 engine for the development community of this application: http://avayalive.com/WaStore/Overview.aspx
There are a few problems that I need to be able to overcome.

Unreal uses meshes in a triangulated form & uses vertex lighting so I need to be able to see the mesh in a triangulated form prior to exporting & allow me to be able to edit those triangles so that the vertex lighting is shown correctly. At current some bad triangles are shown with hard shadows on flat surfaces due to the nature of the triangulation created. With the ability to edit those triangles I can quickly edit the mesh in SU PRE-EXPORT so the creation doesnt have these issues. Other apps such as 3DSM recommend re-tesselating the mesh to breakdown the triangles into smaller surfaces, however this also is detrimental as it increases the polycount, which is at a premium considering the overall level created.

Gaeius recommended the use of this script along with the sandbox "flip edge" tool to see if it would solve the problem. Whilst the triangulation script works the UV as we now know is messed up with the flip edge tool affecting the polygons UV mapping.

So is there a suitable solution that can meet my needs?
BTW: the .alive project is something I plan to open up to the SU community in the coming weeks as there is a lot of potential for modelling, texturing etc & all with a small learning curve they could soon be developping whole environments Some projects also have funding!!