If you want to know what happened in the JFK assassination, you
START with the witnesses and then you use other evidence that NOBODY could have forged. Then you sort out who said something reasonable, who was asleep and didn't have a clue and who was either lying or manipulated by those who did NOT want the truth to be known by the little people.
QUESTION: Is this hypothesized shot trajectory consistent with what these witnesses say they saw?
https://www.youtube.com/watch?v=vClwuJ0yuWM Dr. Glanges, a premed student at that time describes the bullet hole she says she saw
https://www.youtube.com/watch?v=01oaxb00dIE Limo to Detroit, Part 1
https://www.youtube.com/watch?v=stHp1AbPsUw Limo to Detroit Part 2
What the witnesses say they saw PROVES NOTHING but it is a starting point.
Back to the original question: MULTIPLE witnesses in the three YOUTUBE videos say they saw a clean bullet hole through the windshield that looked like it was fired from the front. IF you hypothesize the shot that hit President Kennedy in the neck came through the windshield, then the diagram is a reasonable starting point.