Calculating ranges

[jbmannon]

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.

[TechnoCat]

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

[kikito]

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

[Kazagha]

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.

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-- 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

[jbmannon]

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.

[ivan]

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".

[jbmannon]

Ivan,

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

[ivan]

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