Paths on a surface 
Two types of path deformations
Similarly to paths being distinguishable by the corresponding curve, or on how the curve is travelled, there are two types of path deformations: one more obvious, corresponding to changes of the curve, and other more subtle, related to changes on the color grading of the curve.
On the app below we have examples of homotopic paths, some where the deformation changes the curve and other ones only with changes on the colour grading.
Instructions
In the figure we have an example of two homotopic paths, one is in the first box and the other in the second box. At the third box, by controlling the point of the vertical bar on the right, we can observe a homotopy between the two paths.
On the top horizontal bar, we can also choose other predefined examples of homotopic pairs of paths and observe a deformation between each pair.
