One last change to make before running ExploreNormals.py is to increase the length of the normals to make them visible. We can do this in DisplayNormals . py by adding a multiplier to the end position of the normals, as follows:
middle $=($ vertex $3+q * 0.5)$
$\mathrm{v}=($ middle - vertexl) $* 2 / 3$
median $=$ vertex $1+\mathrm{v}$
nstart $=$ median
self.normals.append ((nstart, nstart + norm * 10))
By multiplying the normal (which has a length of 1) by 10 , it will make them go in the same direction but display a longer-drawn line.