Overview Quads and Topology A big deal of organic modelling workflow spin around good topology of quads (faces with four vertices/edges). Quads allows for many very useful mesh operations, such as selection rings and loops. Quads are predictable which is why they are so useful.
Many applications let you work with non-planar quads. In SketchUp however, it is not so easy. When you modify a vertex of a quad in SketchUp it auto-folds and breaks the quad into two triangles - where as other 3d applications might leave it as one unit.
At the core of every 3d applications, everything consists of triangles - the only difference is how they expose the triangles to the user. However, there is no reason why SketchUp users can't work with non-planar quads - it's just that the tools need to be aware of them.
Quads in SketchUp This toolset is an attempt to begin on such a suite of tools to let SketchUp users work with quads. My approach is conceptually simple: When two faces are separated with a soft edge (smooth only affects shading) then the two faces are treated as one Unit. Click one and you select both and the Entity Info window says you have selected a Surface. Based on that, here is how I define quads in SketchUp:
The definition of a QuadFace was changed again in version 0.6 because the previous versions relied on the Hidden property. The Hidden property is affected by a model's Scenes, so when you copied quad mesh into a new model you would loose the Hidden property of the diagonals.
To update a mesh from the older versions, use: Tools > QuadFace Tools > Convert > Sandbox Quads to QuadFace Quads
Native quad face, face with four vertices.
Two triangles, joined by an edge with the following properties:
Soft = true
Smooth = true
Cast Shadows = false
Border edges can have any property, just not all of them.
Faces that makes up a QuadFace cannot have holes in them.
(Updated in 0.6.0)
Call to Developers I'd encourage all plugin developers of plugins that generate geometry if what they generate can be made compatible with my definition of a QuadFace so we can expand the toolset for dealing with QuadFaces. QuadFaces is key to working with good topology in 3D modelling.
Project Hosting This project is now hosted on BitBucket where the downloads and documentation exists.
I meant to make some videos explaining quads in SketchUp, but I had no time this weekend. But I figured I'd still push it out there for the brave guineapigs who like to punish themselves with new unknown tools.
It has been a wee little distraction from Bezier Surface, but not completely. As I need the same selection routines in both plugins. This has been a playground experiment. Win-win!
SWEET! This has been a long time dream finally realized. Thanks for all your amazing contributions Thomas! We are lucky to have you in our community!
A designer is an emerging synthesis of artist, inventor, mechanic, objective economist and evolutionary strategist. - R. Buckminster Fuller Some of my 3D crap
Fredo6 wrote:As a contribution, I'll include an option to generate quads (under your definition) in Curviloft (the preview display is based on quads, precisely).
That's great Fredo! The more tools we get that generate geometry like this the better topology we can create in SketchUp with better tools.
Been playing with it and it's really great. Thanks again. Been playing with Artisan meshes with some mixed results, but after a few Make Quad operations, I can get the whole mesh to quadrify.
Any plans on adding a Ring Connect option as a way to add additional loops?
A designer is an emerging synthesis of artist, inventor, mechanic, objective economist and evolutionary strategist. - R. Buckminster Fuller Some of my 3D crap
EarthMover wrote: Been playing with Artisan meshes with some mixed results, but after a few Make Quad operations, I can get the whole mesh to quadrify.
I meant to make a whole video tutorial for that. It's best not to make the starting point at the edge of a mesh. That might yield some odd results. And holes in the mesh might also produce unexpected results. And I suspects meshes where the quads are not uniformly laid out, but need star connections could throw some odd results as well. If you find that the quadification of a mesh yields odd results it might help if you manually quadify some of mesh first. A couple of quads around holes and star connections. Got any sample models to share by the way. I did not have any organic models with regular mesh to test on.
EarthMover wrote:Any plans on adding a Ring Connect option as a way to add additional loops?
Gaieus wrote:Holy crap, TT. I saw you post in the (other) forum to Pete and was wondering. Good news is that I seem to have some spare space in my toolbars...
By the way Gaieus, with meshes build from quads, making UV tools becomes easier. It was in fact one of the biggest challenges I had/have with UV Toolkit, being able to sort the geometry into predictable chunks. Now I can build upon the requirement that the mesh is quads, which makes the traversing of the mesh and mapping much easier.
Just for the sake for retaliation and mute your excitement, it's simply a Collapse function. So there! Hah! No magic!
In reality it's a function to call upon all my killer robots to home in on Rich - as you can see from the iconic representation. Yes, that is right, I'm giving everyone who buts Vertex Tools this mighty power! muhahahah!
EarthMover wrote:Any plans on adding a Ring Connect option as a way to add additional loops?
What is a Ring Connect?
It's fundamental for creating support edges for hard subdivision surfaces and to model organic surfaces while still maintaining quads. In Max, the Edit Poly Connect, gives you options to also slide and spread the loops along the width of the edge ring in order to "weight" the edges, define creases, etc. In Sketchup, you could always move a copy of a loop, but on an organic surface it doesn't always line up right. Even a simple option to connect edge rings at the midpoints would be helpful.
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A designer is an emerging synthesis of artist, inventor, mechanic, objective economist and evolutionary strategist. - R. Buckminster Fuller Some of my 3D crap
A question: Is there a way to force the vertices of the quad to be coplanar? If a quad consist of two triangles rotate this two triangles until they lay on the same plane and then delete the shared edge. Is that possible?
Daniel S wrote:A question: Is there a way to force the vertices of the quad to be coplanar? If a quad consist of two triangles rotate this two triangles until they lay on the same plane and then delete the shared edge. Is that possible?
Yes, though, it'd also distort the connected faces.
Elementary question: What is the difference between a ring and a loop? I couldn't seem to figure out the images, or why one is called a ring and one is called a loop.
I take the slow, deliberate approach in my aimless wandering.
mitcorb wrote:Elementary question: What is the difference between a ring and a loop? I couldn't seem to figure out the images, or why one is called a ring and one is called a loop.
Ring selects the next opposite edge in the connected quadfaces. Loop selects the next connected edge at each vertex with a valence of 4 and does not share a face with previous face.
A question: Is there a way to force the vertices of the quad to be coplanar? If a quad consist of two triangles rotate this two triangles until they lay on the same plane and then delete the shared edge. Is that possible?
Daniel S
I added a function that projects the selected faces ( any face ) to a best fit plane. ( Best fit plane is based on the selection ). It also ensures that quads connected to the selection are triangulated so they don't break due to SketchUp's AutoFold feature. Then I added a separate Remove Triangulation function.
Both will be present in the next release. (Among other updates/changes)
Win-win!
