New export: 3D Patterns

[Former user]

Create patterns in 3D format.

Possibly use Wavefront .obj format. Recommend generating patterns using quadrangles. Recommend generating patterns so that edge vertices are aligned in pairs along seams so that seams can be 'sewn' together using Blender or other 3D stitching app.

[Former user]

Per online discussions, the preferred format is triangulated mesh. Blender developers are considering importing the native valentina pattern file *.val and generating the triangular mesh as a Blender plugin.

[Roman Telezhynskyi]

Blender developers are considering importing the native valentina pattern file *.val and generating the triangular mesh as a Blender plugin.

Wow, but val format too unstable and complicate. Don't think it is good idea. But if only we have library for our format. See issue #126.

[Roman Telezhynskyi]

Update for issue description.

For creation 3D patterns better create new export format. This format should include informations about workpieces, passmarks, measurements, data about size and height and so on. Main idea is left for Valentina care about all calculations and export data (workpiece points coordinates, passmark coordinates) to this new format. Which language use XML or JSON still need discuss.

[Former user]

So passmarks should be moved up to v.0.4.0?

[Roman Telezhynskyi]

Yes, all that need for creation 3D pattern.

[Susan Spencer]

GSOC description:
Knowledge Prerequisite: Qt, C++, mercurial.
Skill level: high.
Mentor: Roman Telezhynskyi
For purposes of cloth simulation each pattern layout should be exported to 3D Wavefront .obj file in form of a mesh grid. There are two kinds of meshes that use for this purpose: triangulated and quadrangled meshes. Density inside the pieces is important - more triangles/quadrangles = more folds/flexibility. Less = lower polygons, more stiffness. Example of mesh grid:

For simulation of fabric the triangulated mesh style is best:

After the simulation has happened and the pieces have been joined, draped, creased etc. convert to quad mesh. This becomes very important to have, this lowers the polygons and also allows for a modeller to add embelishments that the pattern cad program cannot make - it allows zippers, buttons, eyelets, stiching to be added easier with "displacement modifiers", it allows portions to be selected by human eye easier, it allows for boolean/ uv transformations (converting the bottom mesh to follow the path of the top mesh once "formed")

In library VObj we begin implementation triangulated mesh, but our realization has disadvantages:

• Only use edge points of each workpiece.
• Don't create points inside of shape.
• Wrong using triangulation Delaunay make in some cases wrong triangles.

Expected results:
In static library make export pattern layout in 3D Wavefront .obj file in form of quadrangle-based mesh and (or) triangulated mesh grid. Matching vertices along seamlines, no seam allowances.

[Roman Telezhynskyi]

The are essentially two approaches to free quad meshing:

• Direct methods generate a quad mesh directly, usually by some advancing front method. The Paving paper is a standard reference.
• Indirect methods generate some intermediate decomposition of the domain (e.g. triangles) and then produce an all-quad mesh through recombination and/or further decomposition. Q-Morph is an example.

[Roman Telezhynskyi]

Removing milestone: v0.6.0 (automated comment)