Deform2D is an interactive demo program which implements the 
As-Rigid-As-Possible Shape Manipulation technique described in:

As-rigid-as-possible shape manipulation. Takeo Igarashi, Tomer Moscovich, John F. Hughes. 
ACM Transactions on Graphics, 24(3), July 2005, pp. 1134-1141. 

See http://www-ui.is.s.u-tokyo.ac.jp/~takeo/research/rigid/index.html for the original
paper, software, and demo java app (which does not include source).

This simple GLUT application can be used to deform a 2D mesh based on a set of constraint points 
placed at the mesh vertices using the right mouse button. Once two constraints are placed, the 
linear equations defining the deformation are automatically precomputed. Then you can move the 
constraints using the left mouse button. 

By default a square grid of triangles is generated. You can load other triangle meshes 
in .OBJ format (*) by pressing the 'f' key. Note that the mesh will be projected into the 
X/Y plane, and the view automatically scaled and translated. Also, if your mesh has lots of 
vertices (more than a few hundred), the pre-computation will take some time (the implementation 
here does not use sparse matrices). I have included the example mesh used above, named 'man.obj'.

The source includes the WildMagic 2 library, of which a tiny part is used. This is an out-of-date 
version, see geometrictools.com for the most recent WildMagic library. Note that you can't just 
drop newer versions, because the namespace and some of the interfaces have changed (but it 
would not be a lot of work to update this code).

UI controls:

right mouse - set / remove control point (control points can only be placed at vertices)
left mouse - move control point
'f' - load new .obj mesh

Source files:

I wrote this code in 2006 (except for the GLUT interface, which I just hacked 
up so I wouldn't have to distribute the original GDI app). I don't really remember how 
it works, and I don't have time to provide developer support. Good luck!

Deform2D.cpp contains the GLUT and UI code
src\RigidMeshDeformer2D.* implements the paper (sets up matrices, maintains constraints, etc)
src\TriangleMesh.* is a basic triangle mesh class
src\LinearAlgebra.* is used by the triangle mesh class
src\WmlExtLinearSystem.* implements LU decomposition and backsubstitution
src\WmlExtTriangleUtils.* implements some triangle utility functions (I think only ::BarycentricCoords is actually used)
src\rmsdebug.h is used by debug printing
Wml\* is the WildMagic2 library (the compiled DLL is included)

(*) your .OBJ mesh must have face ('f') lines in the form vtx/tex/norm or vtx//norm. Some packages export just the vertex indices, which the OBJ loader can't handle.

- Ryan Schmidt (rms@unknownroad.com) - Feb 2009