Blend Shapes

This code load a set of meshes corresponding to different key poses for the same character face.
In the current implement all the poses are stored as an array of meshes (see src/blend_shape directory). The first entry of the array will be considered to be the reference pose (faces_storage[0]).
The GUI propose a set of sliders to control the weights associated to each pose but is without effect in the current state. > Implement a blend shape deformation controled interactively by the blend shape weights using the formulation: \[\displaystyle q_i=p_i + \sum_{j}^{N_{poses}} w_j \, d_{ij}\]

• • \(q_i\): Vertex coordinates of the deformed shape.
  • \(p_i\): Vertex coordinates of the reference pose.
  • \(N_{poses}\): The number of key poses (excluding the reference one).
  • \(w_j\): Blend shape weight \(\in[0,1]\).
  • \(d_{ij}\): Difference between the \(i\)th vertex positions of the key pose \(j\) and \(p_i\).

• Check that you can adapt each expression using its own weight.
• Test also in extrapolating the deformation using weights outside \([0,1]\) range.