Collisions between 2 of the same type
BlitzPlus Forums/BlitzPlus Programming/Collisions between 2 of the same type
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| Can somebody please write me a sample code showing how check a collision between 2 objects of the SAME type? Because this doesn't work... If imagescollide(im,a\x,a\y,0,im,a\x,a\y,0) |
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I'm not 100% sure but I think you would do this:
For a.apple=each apple
For a2.apple=each apple
If ImagesCollide(a\img,a\x,a\y,0,a2\img,a2\x,a2\y)
;dsfjdslvjdsfkljdsgds;
Endif
next
next
That's how I would do it anyway. |
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| ok, say i wanted to check the collision between more than just two objects, say 100. then how would i do that? |
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| Ked's code will work with more than 2 objects, in fact it works for all objects currently in memory, however it does not discount two objects that are one and the same object. Here is another way of doing it:
For Apple.AppleObject=each AppleObject
For OtherApple.AppleObject=each AppleObject
If Handle(Apple)<>Handle(OtherApple) then
If ImagesCollide(Apple\Image,Apple\X,Apple\Y,Apple\Frame,OtherApple\Image,OtherApple\X,OtherApple\Y,OtherApple\Frame) then
;do whatever you want now that you've detected a collision
endif
endif
next
next
This is the easiest way of doing things, and if you are only comparing 100 objects against all 100 other objects every frame (roughly 10000 imagescollide checks) then it may be quick enough for what you want. |
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| will this code work if i wanted to make a bunch of particles, all the same type, to move around and bump into eachother? |
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| Don't see why not. |
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| What does the command "Handle" do? It,s not in the command reference. |
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| Handle & its related partner Object are two commands not documented as official blitz commands. I will try to explain by giving you an example, there are many uses for this command the main one being though the ability to go directly to a particular type instance without having to loop through them all. Type AppleObject Field Ripeness Field Taste Field Color Field Name$ end type Apple.AppleObject=new AppleObject Apple\NAme="jonathan" AppleHandle=Handle(Apple) ;The Handle(Apple) command returns an integer which holds a kind of pointer to this particular type instance. SecondApple.AppleObject=new AppleObject SecondApple\Name="granny smith" TheFirstApple.AppleObject=Object.AppleObject(AppleHandle) ;the Object command when used as above will return either the relevant type instance as it does here, or null if it does not exist. Print TheFirstApple\Name;should print "jonathan" The way I used it in the code earlier (a few posts up) allows us to check if we are looking at the same type instance in each loop - if the handle returned is the same for both then we are looking at the same type instance. It may take some time for this command's usefulness to become apparent, and you may need to play with it a little so don't worry if you don't get it just yet. |
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| Ok, I have one more question. I know i should already know this, but I don't. When I create a type, I put in something like, " appleobject.appleobject = new appleobject" I don't know why I put it. That's just how I do it. Could somebody explain what this command means? I usually see it done like this, "apple.appleobject = new appleobject" What's the difference? |
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| Not too much difference at all - as an example, when you declare a variable as a string you do so by adding $ to the end of the variable name, when you declare a floating point variable you add #. In the case of a custom type you add .TYPENAME when declaring the variable. There is nothing wrong with doing it your way but it can be a little confusing. Examples: A.Appleobject=new AppleObject YetAnotherInstance.AppleObject=new AppleObject CDEF.AppleObject=new AppleObject All of those would create a new instance of a type object, the first being called A, the second being called YetAnotherInstance, and the third being called CDEF. The name you give to the type instance really does not matter. You don't have to name a new type instance as the name of the type itself |
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| Thanks Matty! |
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| FYI, the Handle function is great and useful for some advanced tricks, but it is completely unnecessary in this example. You can compare two Type instances to see if they are the same one or not without using the Handle command. In other words, this code:
For Apple.AppleObject=each AppleObject
For OtherApple.AppleObject=each AppleObject
If Apple <> OtherApple then
If ImagesCollide(Apple\Image,Apple\X,Apple\Y,Apple\Frame,OtherApple\Image,OtherApple\X,OtherApple\Y,OtherApple\Frame) then
;do whatever you want now that you've detected a collision
endif
endif
next
next
will work exactly the same as the code Matty first posted (notice the lack of the Handle function calls). Note that this actually does make sure it is the exact same or different object by comparing their memory addresses internally, it does not compare the CONTENTS of the objects. For example, this code:
Type TestType
Field x, y
End Type
a.TestType = New TestType
b.TestType = New TestType
a\x = 10
b\x = 10
a\y = 10
b\y = 10
If a = b Then
Print "The same!"
Else
Print "Not the same!"
EndIf
will print out "Not the same!" even though the contents of the two objects are the same. Using = or <> between two Type instances will only check if they are the exact same instance of the object, it doesn't bother to look at the data inside them. If you wanted to see if their values are the same, you'd have to manually check x and y of each one. |
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| this code: For Apple.AppleObject=each AppleObject For OtherApple.AppleObject=each AppleObject If Apple <> OtherApple then If ImagesCollide(Apple\Image,Apple\X,Apple\Y,Apple\Frame,OtherApple\Image,OtherApple\X,OtherApple\Y,OtherApple\Frame) then ;do whatever you want now that you've detected a collision endif endif next next (sorry, dont know how to make one of those code boxes) It only works if I want 2 instances to collide with eachother...But say I want 100s! without doing this... b1.ball = new ball b2.ball = new ball b3.ball = new ball b4.ball = new ball b5.ball = new ball b6.ball = new ball b7.ball = new ball b8.ball = new ball b9.ball = new ball etc.... Thats not what I want... |
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