Based on Jun Mitani's ORIPA desktop application, ORIPA for Android enables origami designers and enthusiasts to test their crease pattern ideas even while on the go! ORIPA for Android retains the ability to check crease patterns against local flat foldability rules and test fold valid crease patterns. Useful for when inspiration for a new origami design strikes while you're away from your computer, or during long flights to origami conventions with no Wi-Fi.
Starting in 2010 when I began to design origami up until 2015, I typically drew my crease patterns (CPs) with colored pens on graph paper before redrawing the final CP on a computer using vector drawing software. In 2016, I began to use the desktop version of Jun Mitani's ORIPA app, and it made my design process much faster. Instead of redrawing entire CPs on paper every time I made a change to the model, I could easily duplicate existing CP files and make incremental changes to the new files. Sharing mountain/valley colored CPs became much easier. I also exported folded shapes in a vector format that I could paste into diagrams.
While working on a computer was fine, sometimes ideas would come while I was away from my computer, and I wanted a way to record those ideas. Thus, after a few months of using the desktop ORIPA, I started to work on an Android version of ORIPA. I worked on the project on and off for about a year before it became a working prototype in 2017.
The core experience for the user remains the same between the desktop ORIPA and ORIPA for Android. Users can still draw, validate, and test fold CPs. Under the hood, flat CPs are still represented by lines and points, and the folded CPs are still represented by vertices, half-edges, and faces. However, I took the opportunity of a new platform to introduce changes. The most obvious is designing and implementing a new mobile-friendly interface. I also fixed some bugs that existed in desktop ORIPA at the time (e.g., undo issues), added/modified the drawing tools, rewrote many underlying data structures, and more. I tried out a new traversal method for producing overlap view of folded models, but that is still a work in progress.
Actually, the entire app is still a work in progress, with a lot of room for more improvement and optimization (and bug fixes, of course). But I'm happy to see that so many people have gotten good use out of the app already since the time of ORIPA for Android's beta release.
-Michelle, May 2021
P.S. The desktop version of ORIPA has gotten many updates from the original and other contributors as well these past few years - try it out! For the more advanced users, Orihime (オリヒメ) by Meguro Toshiyuki is also an option with more tools and a great fold overlap solver.
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