Calculate direction angle from two vectors?

Posted by james.ingham on Stack Overflow See other posts from Stack Overflow or by james.ingham
Published on 2010-04-03T11:51:32Z Indexed on 2010/04/03 16:13 UTC
Read the original article Hit count: 346

Filed under:

vectors

|

angle

|

algorithm

Hi,

Say I have two 2D vectors, one for an objects current position and one for that objects previous position. How can I work out the direction of travel?

This image might help understand what I'm after:

alt text

Thanks

-James

© Stack Overflow or respective owner

Related posts about vectors

Unity: parallel vectors and cross product, how to compare vectors

as seen on Game Development - Search for 'Game Development'
I read this post explaining a method to understand if the angle between 2 given vectors and the normal to the plane described by them, is clockwise or anticlockwise: public static AngleDir GetAngleDirection(Vector3 beginDir, Vector3 endDir, Vector3 upDir) { Vector3 cross = Vector3.Cross(beginDir… >>> More
Any reliable polygon normal calculation code?

as seen on Game Development - Search for 'Game Development'
I'm currently calculating the normal vector of a polygon using this code, but for some faces here and there it calculates a wrong normal. I don't really know what's going on or where it fails but its not reliable. Do you have any polygon normal calculation that's tested and found to be reliable? … >>> More
Adding multiple vectors in R

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a problem where I have to add thirty-three integer vectors of equal length from a dataset in R. I know the simple solution would be Vector1 + Vector2 + Vector3 +VectorN But I am sure there is a way to code this. Also some vectors have NA in place of integers so I need a way to skip those… >>> More
Programmatically creating vector arrows in KML

as seen on Stack Overflow - Search for 'Stack Overflow'
Does anyone have any practical examples of programmatically drawing icons as vectors in KML? Specifically, I have data with a magnitude and an azimuth at given coordinates, and I would like to have icons (or another graphical element) generated based on these values. Some thoughts on how I might… >>> More
is it wasteful/bad design to use a vector/list where in most instances it will only have one element

as seen on Stack Overflow - Search for 'Stack Overflow'
is it wasteful/bad design to use a vector/list where in most instances it will only have one element? example: class dragon { ArrayList<head> = new ArrayList<head> Heads; tail Tail = new tail(); body Body = new body(); dragon() { theHead=new head(); … >>> More

Related posts about angle

Finding the angle of a fleeing dodo.

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm coding some critter AI for a game i am working on for my Unity 3D project. I have no programming background and have been stumbling through this using tutorials and other peoples scripts. My problem is that i want my critter to run directly away from the player when the player kicks it. I need… >>> More
ANGLE wined3d in reverse

as seen on Internet.com - Search for 'Internet.com'
<b>Wine-Reviews:</b> "Were happy to announce a new open source project called Almost Native Graphics Layer Engine, or ANGLE for short. The goal of ANGLE is to layer WebGLs subset of the OpenGL ES 2.0 API over DirectX 9.0c API calls." >>> More
Introducing the ANGLE Project

as seen on Google Code - Search for 'Google Code'
We're happy to announce a new open source project called Almost Native Graphics Layer Engine, or ANGLE for short. The goal of ANGLE is to layer WebGL's subset... >>> More
What does this piece of code in C++ mean? [closed]

as seen on Programmers - Search for 'Programmers'
const double pi = 3.141592653589793; const angle rightangle = pi/2; inline angle deg2rad(angle degree) { return degree * rightangle / 90.; } angle function1() { return rightangle * ( ((double) rand()) / ((double) RAND_MAX) - .5 ); } bool setmargin(angle theta, angle phi, angle margin)… >>> More
Point inside Oriented Bounding Box?

as seen on Game Development - Search for 'Game Development'
I have an OBB2D class based on SAT. This is my point in OBB method: public boolean pointInside(float x, float y) { float newy = (float) (Math.sin(angle) * (y - center.y) + Math.cos(angle) * (x - center.x)); float newx = (float) (Math.cos(angle) * (x - center.x) - Math.sin(angle)… >>> More