The first point was always set to the brush radius, even when the
angle setting was used. Additionally, the approximation for the
pen direction started at (0, 0).
This fixes the issue by overwriting the radius of the first point
once we get the first extension sample and with that the first
approximation of the pen direction.
The pen direction is also set to the initial direction from the
first to the second point.
2c773ce857