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Help (Image Collision in an Array)

 
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Danny769



Joined: 01 Feb 2006
Posts: 55
PostPosted: Sun Apr 30, 2006 11:45 am    Post subject: Help (Image Collision in an Array) Reply with quote
How Do I do an image Collision check for X,Y Controled Objects In an Array?


Yes i know leave it for me to come up with the fun problems
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Danny769



Joined: 01 Feb 2006
Posts: 55
PostPosted: Tue May 02, 2006 8:14 pm    Post subject: Reply with quote
Would compairing the images in a double do loop do the job

Code:
for i = 0, 20 do
   for j = 0, 20 do
      -- Colision for Array1.[i]Vs Array2.[j]
   end
end


What you think?
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LuMo



Joined: 21 Aug 2005
Posts: 410
Location: Austria
PostPosted: Wed May 03, 2006 2:02 am    Post subject: Reply with quote
you will double check images then

as you do check:
1 -> 1 <-- nonsense always collision
1 -> 2
1 -> 3
1 -> ..
1 -> 20

2 -> 1 <-- already checked in first "pass"
2 -> 2 <-- nonsense always collision
2 -> ..

greets
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Danny769



Joined: 01 Feb 2006
Posts: 55
PostPosted: Wed May 03, 2006 2:19 am    Post subject: Reply with quote
J = 1
I = 2

How would you do it?
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Shine



Joined: 03 Dec 2004
Posts: 728
Location: Germany
PostPosted: Wed May 03, 2006 7:21 am    Post subject: Reply with quote
Danny769 wrote:
J = 1
I = 2

How would you do it?


A first hack could look like this:

Code:

function isInRectangle(x, y, x0, y0, x1, y1)
   return x >= x0 and x < x1 and y >= y0 and y < y1
end

function overlaps(object1, object2)
   local o1_x0 = object1.x0
   local o1_y0 = object1.y0
   local o1_x1 = o1_x0 + object1.boundingBoxWidth
   local o1_y1 = o1_y0 + object1.boundingBoxHeight
   local o2_x0 = object2.x0
   local o2_y0 = object2.y0
   local o2_x1 = o2_x0 + object2.boundingBoxWidth
   local o2_y1 = o2_y0 + object2.boundingBoxHeight
   return    isInRectangle(o1_x0, o1_y0, o2_x0, o2_y0, o2_x1, o2_y1) or
      isInRectangle(o1_x1, o1_y1, o2_x0, o2_y0, o2_x1, o2_y1) or
      isInRectangle(o2_x0, o2_y0, o1_x0, o1_y0, o1_x1, o1_y1) or
      isInRectangle(o2_x1, o2_y1, o1_x0, o1_y0, o1_x1, o1_y1)
end

objects = {
   { x0=60, y0=20, boundingBoxWidth=50, boundingBoxHeight=30 },
   { x0=20, y0=20, boundingBoxWidth=50, boundingBoxHeight=30 }}
for i = 1, table.getn(objects) do
   for j = i, table.getn(objects) do
      if i ~= j then
         local object1 = objects[i]
         local object2 = objects[j]
         if overlaps(object1, object2) then
            print("collision of " .. i .. " and " .. j)
         end
      end
   end
end


Would be better to create classes for rectangles with meta-functions for operators on it.
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Danny769



Joined: 01 Feb 2006
Posts: 55
PostPosted: Wed May 03, 2006 10:52 am    Post subject: Reply with quote
Thanks ill try this, seem like alot of extra work though,
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