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Posted: **Sat Oct 29, 2011 11:10 am**

Hey I'm working on a project and I'm trying to calculate ranges in a radius from my actors. I'm having difficulty working out what to do. Any advice would be great.

Posted: **Sat Oct 29, 2011 3:32 pm**

jbmannon wrote:Hey I'm working on a project and I'm trying to calculate ranges in a radius from my actors. I'm having difficulty working out what to do. Any advice would be great.

If what you're trying to do is find things within a circle around the actor then:

Code: Select all

if euclidean_distance < (actor1.radius + actor2.radius) then
  print("COLLISISON!")
end

Posted: **Sat Oct 29, 2011 3:33 pm**

Could you explain what do you mean by "ranges in a radius from my actors"? It's impossible to know without more context.

Posted: **Sat Oct 29, 2011 10:15 pm**

That is good thinking TechnoCat.

You could find the regular distance between two points with the following function(euclidean distance?). Where x1/y1 is one actor, and y1/y2 is the other.

Code: Select all

-- Returns the distance between two points.
function math.dist(x1,y1, x2,y2) return ((x2-x1)^2+(y2-y1)^2)^0.5 end

Taken from Taehl's post on the Share You Utils thread, it's well worth checking out;
http://love2d.org/forums/viewtopic.php?f=3&t=2429

-Kazagha

Posted: **Mon Oct 31, 2011 11:00 am**

Thank you everyone. Obviously calculating a circle is beyond my skill level. I may be useing Kazagha's bit of code, or more likely something similar.

Posted: **Mon Oct 31, 2011 11:20 am**

jbmannon wrote:Thank you everyone. Obviously calculating a circle is beyond my skill level. I may be useing Kazagha's bit of code, or more likely something similar.

Here's an 'optimized' version of the circle vs circle algorithm:

Code: Select all

function circleIntersect ( x1, y1, r1, x2, y2, r2 )
  local dx, dy = x1 - x2, y1 - y2
  local d = dx * dx + dy * dy -- squared distance
  local radii = r1 + r2
  return d < ( radii * radii ) -- squared distance vs squared radii sum
end

It avoids ^ and math.sqrt operations which are considered "cpu costly".

Posted: **Mon Oct 31, 2011 2:04 pm**

Ivan,

This should return true if they are within range of each other correct?

Posted: **Mon Oct 31, 2011 3:16 pm**

Yes, where x1, y1 is the position of circle 1, x2, y2 is the position of circle 2 and r1 and r2 are their radii respectively

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