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Finding the position directly behind a player

by wolfknight
Tags: directly, player, position
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wolfknight
#1
Jan22-13, 09:52 PM
P: 5
I'm attempting SCIENCE by using math that I have never used before, nor do I understand (despite reading numerous articles, watching all of the khanacademy videos, etc etc)

I'm attempting to use trig to locate a point directly behind another player in Minecraft.
I've read through these three pages:
http://stackoverflow.com/questions/4...-calculate-end
http://en.wikipedia.org/wiki/Spheric...an_coordinates
http://www.opentk.com/node/2505

and have come up with this code:

double dEntityDistance = getPlayer().getDistanceToEntity(player);
		
double dNewX = /* The current player */getPlayer().posX  - dEntityDistance * Math.sin(Math.toRadians(/* The player we want the position behind */ player.rotationYaw % 360)) * Math.cos(Math.toRadians(-player.rotationPitch));

double dNewZ = getPlayer().posZ - dEntityDistance * Math.cos(Math.toRadians(player.rotationYaw % 360)) * Math.cos(Math.toRadians(-player.rotationPitch));
I know nothing about matrices (which some have suggested), nor do I know very much about trig. If anybody would be kind enough to explain a bit about those two subjects (or whichever one would help me with my problem), I would be very grateful.
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mfb
#2
Jan23-13, 10:59 AM
Mentor
P: 11,601
Behind relative to what? The plane, or the direction the player is looking to?
As a first step: Do you understand how Minecraft stores the orientation of the player? The definition of those parameters should give you a direct way to calculate x,y,z in front of the player. Behind is just the same, but with opposite signs for the distance.

Comments directly in formulas? Really?
wolfknight
#3
Jan23-13, 04:00 PM
P: 5
Quote Quote by mfb View Post
the direction the player is looking to?
The direction the player is facing, yes, I apologize for not clarifying.

Quote Quote by mfb View Post
As a first step: Do you understand how Minecraft stores the orientation of the player?
I've been trying to find out for the last couple days. Notch and Jeb do it in a really really bad way, which is why I've been having loads of trouble.

Quote Quote by mfb View Post
Comments directly in formulas? Really?
Actually no, it's just that I was clarifying which entity was which.

wolfknight
#4
Jan24-13, 12:10 PM
P: 5
Finding the position directly behind a player

I fixed this. Minecraft rotations are completely back-asswards, and it took me a while, but I now can successfully teleport behind other players.


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