Finding the position directly behind a player


by wolfknight
Tags: directly, player, position
wolfknight
wolfknight is offline
#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
mfb is offline
#2
Jan23-13, 10:59 AM
Mentor
P: 10,846
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
wolfknight is offline
#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
wolfknight is offline
#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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