Editing a Quad Filled mesh?

[ExplodeCreative]

Hey all,

I love the quad mesh feature. I draw a mesh, use Fill Quad Mesh and it works nicely. But quite often I want to add more points to that already filled mesh and it seems to have a real problem with that. And sometimes Undo isnt an option. Is there any way to add more quads to an already filled quad mesh?

[synthsin75]

If you use Draw>Triangulate 2D Mesh, it will triangulate in real-time, as you make changes.
Granted, this is only available for triangulation, not quads.

[ExplodeCreative]

Thanks Synthsin,

Sounds like there's no reason not to use Triangulate instead for pretty much everything then?

[hayasidist]

Is there any way to add more quads to an already filled quad mesh?

Sledgehammer approach: add points / paths as needed; delete all the shapes (use the delete shape tool that looks like an X - select the tool and sweep the mouse over the shapes, no need to click-move-click etc); re-run the fill quad tool
scalpel approach: make sure you have autofill/auto stroke off (so you don't create shapes that you might not want); delete the shapes that will be affected by the changes; make the changes; re-run the tool (it will fill quads and tris)

something to bear in mind - adding a point in an edge that is shared by two quads will affect both quads -- so both need to be changed as above
hth

[SimplSam]

... Sounds like there's no reason not to use Triangulate instead for pretty much everything then? ...

It will depend on what you are doing with it. The key point about triangulation (and yes it sounds obvious) - is the mesh is made of Triangles. With Quad meshes - you can have Quads and/or Triangles. I find it easier to work with quads, especially for perspective work - but still use triangulation, especially for complex shapes - as they are quicker to create. We also now have the new Live Smart Mesh to play with too.

The creation and use of Quad meshes is illustrated very well in the "How to create and animate Quad Meshes" - Moho Tutorial: https://www.youtube.com/watch?v=3HP85jJGhf8

At: 15:00 (https://youtu.be/3HP85jJGhf8?t=900) he breaks a complex quad mesh, edits & re-establishes it.

[Greenlaw]

I use quads as much as I can in a mesh, and switch to triangles only when the quads fail my intended use. This is true whether I'm working in 2D or 3D animation and the reason is that quads are generally easier to work with and allow cleaner polygon flow. (The latter is more significant when modeling 3D meshes but it can apply to 2D meshes as well.) Using quads or tris is not an either or situation either, you can mix both in a shape as appropriate.

As SimplSam noted, it depends on what you want to do with the mesh.

The best way to learn when to use which polygon type in a mesh is to work with it. After some experimentation, knowing when to use what becomes second nature.

General tips about mesh warping:

A Perspective Warp, or mesh made of a single quad, can be used for true perspective warping. This means the image can be distorted using the rules for perspective drawing. Once you attach another point, it loses this quality, as seen in the image below...



In the first two images, this most noticeable in the vertical spacing of the planks. The one using Perspective Warp is distorting the image properly along an unseen perspective grid, and the regular Quad is spacing the planks in a regularly spaced grid.

As a bonus, I checked to see what happens when I tripled the shape (the third image)...and it totally broke. So, while triangles can display polygon faces more reliably, they might not distort the image as predictably as a quad.

A mesh with multiple quads can be used to deform an image in complex ways. Quads are the easiest and cleanest mesh to work with. However, when a quad is distorted too much, it can become non-planar and disappear or distort an image unpredictably.

A triangle cannot become non-planar so a mesh made of multiple triangles will display reliably. However, when distorted too far, triangles can distort the image unpredictably.

You can mix quads and triangles in the same mesh to get the best qualities of both polygon types.

Images are not distorted along curved lines, only along the straight edge between two points. If you need to distort an image along a curve, you need to add more polygons to reduce the faceting along the edges.

When creating a complex mesh, I like to duplicate my pre-converted vector layer and hide it, so I have a backup layer to regress to if I decide to change the mesh structure or polygon type.

Hope this helps explain why we need each of these different types.

[Greenlaw]

Getting back to the original request...

For really complex meshes, if you're not hung up on using only quads for your mesh, Smart Warp lets you very easily add to an existing complex mesh...just draw in the mesh and it updates dynamically. Smart Warp uses triangles but I love this latest mesh warping tool.

If you've already created your mesh using a regular vector layer, you can do what I do:

1. Select the layer.
2. Choose the Select Shape tool and click Select All.
3. Press the Delete key. This will delete all of the shapes.
3. Make your edits to the mesh.
4. Run Hayasidist's Fill Quad Mesh (Script >Draw >Fill Quad Mesh.) This will create new quad shapes for every valid polygon in your mesh.

Hope this helps.

[ExplodeCreative]

Thank you all so much! Perfect. You guys really make a huge difference for us learners.