[AS3]Array.sortOn not accurate?

[Fall_X]

Ok, here's some code I used :

var transformedSurfaces:Array=surfaces.sortOn("depth",Array.DESCENDING|Array.NUMERIC);
for(var i:int=0;i<transformedSurfaces.length;i++) {
	trace(transformedSurfaces[i].depth);
}

And this is the result I got :

205.44603367212753
182.78833899621128
160.130644320295
138.99973123326004
138.99973123326004
138.99973123326004
138.99973123326004
138.99973123326004
138.99973123326004
114.81525496846251
114.81525496846251
114.81525496846251
92.15756029254628
92.15756029254628
90.63077870366499
90.63077870366499
90.63077870366499
73.72604823403702
69.49986561663002
48.368952529595056
48.36895252959505
48.36895252959505
48.36895252959505
37.47373675257102
37.47373675257102
30.242796788862044
30.242796788862044
24.18447626479752
24.18447626479752
1.5267815888812777
0
0
0
0
0
-24.184476264797524
-24.184476264797524
-24.184476264797524
-42.26182617406994
-42.26182617406994
-46.84217094071377
-48.36895252959505
-48.36895252959505
-48.36895252959505
0
-82.178413468851
-82.178413468851
-82.178413468851
-2.5357095704441965
-8.452365234813989
-89.10399711478371
-90.63077870366499
-90.63077870366499
-21.130913087034973
-31.696369630552457
-132.89260487773493
-132.89260487773493
-137.47294964437876
-138.99973123326006
-138.99973123326006
-138.99973123326006
-157.07708114253245
-172.80919217251602
-172.80919217251602
-172.80919217251602
-181.26155740733
-181.26155740733
-181.26155740733
-205.44603367212753
-223.52338358139994
-228.10372834804377
-263.43997087618095
-263.43997087618095
-263.43997087618095
-271.89233611099496
-271.89233611099496
-271.89233611099496
-314.15416228506496
-362.52311481465995
-362.52311481465995
-362.52311481465995
-362.52311481465995
-362.52311481465995
-362.52311481465995
-404.7849409887299
-495.41571969239493
-495.41571969239493
-495.41571969239493
-495.41571969239493
-495.41571969239493
-495.41571969239493
-495.41571969239493

Note that there's a zero out of place.

I also tried a simple Array.sort(Array.DESCENDING|Array.NUMERIC), and had the toString() function of my objects return the depth field, and that way it was accurate but a lot slower.

So, any ideas?

Thanks.

[T1ger]

Post the input-array?

[AfternoonDelite]

Could this be your problem?

EXFGHT% said on Jun 16, 2006 at 9:43 PM :

Array.sortOn fails if the field to be sorted on in the underlying Object uses a property getter function, it will only work if the field is stored as a normal var.

from here

[Fall_X]

Nope, the field is a normal var.

The input var (only the values of the field I'm sorting on) :

-2.816829376715345
-9.389431255717817
-23.473578139294542
-35.21036720894181
34.19799306009999
23.68865115012508
-488.4209527080526
-353.1790371435708
-264.88427785767806
-176.5895185717854
-155.9157170681336
-135.2419155644818
-46.94715627858908
88.29475928589271
108.96856078954451
129.64236229319633
-488.4209527080526
-353.1790371435708
-255.49484660196026
-197.2633200754372
-176.5895185717854
-88.2947592858927
0
20.673801503651806
41.34760300730362
129.64236229319633
-488.4209527080526
-353.1790371435708
-255.49484660196026
-129.6423622931963
-167.20008731606757
-41.34760300730362
-78.90532803017489
-20.67380150365181
0
64.82118114659816
108.96856078954451
129.64236229319633
-488.4209527080526
-353.1790371435708
-255.49484660196026
-129.6423622931963
-167.20008731606757
-41.34760300730362
-78.90532803017489
-20.67380150365181
0
20.673801503651806
41.34760300730362
129.64236229319633
-488.4209527080526
-353.1790371435708
-264.88427785767806
-129.6423622931963
-167.20008731606757
-41.34760300730362
-78.90532803017489
-20.67380150365181
0
88.29475928589271
108.96856078954451
129.64236229319633
-488.4209527080526
-353.1790371435708
-264.88427785767806
-176.5895185717854
-88.2947592858927
0
88.29475928589271
153.11594043249087
197.2633200754372
-488.4209527080526
-400.1261934221599
-311.83143413626715
-223.53667485037448
-135.2419155644818
-46.94715627858908
41.34760300730362
129.64236229319633
34.19799306009999
69.51589677445708
23.68865115012508
0

It's quite important that I find a way to fix this - when Im' using sort (in combination with toString()) I'm getting 40 fps, if I use sortOn I'm getting 110 fps. It's for my isometric engine thingie. Until now I've settled with the sort-approach, but off course speed is important here.

[mr_malee]

something must be wrong with your depth var because mine works:

var i:int = 500;
var sortArray:Array = [];

while(--i >= 0){
	
	var depth:Number = Math.random() * 1000 - 500;
	
	var ob:Object = {}
	
	if(Math.random() < .05) depth = 0;
	
	ob.depth = depth;
	
	sortArray.push(ob);
}

var transformArray:Array = sortArray.sortOn("depth", Array.NUMERIC | Array.DESCENDING);

for(i = 0; i<transformArray.length; i++){
	
	trace(transformArray[i].depth)
}

[Fall_X]

I'm guessing it's some floating point accuracy problem.

I managed to work around it by adding a number to the depth of my "sprites" (ie the objects that don't have to be skewed in the iso engine). My player character was always at coordinate 0,0,0 (in camera space), and it was flickering, ie sometimes it was underneath the tile he was standing on, and sometimes he was above it. If the difference between it's depth and the tile he was on was very small, the sort sometimes put them in the wrong order, but by increasing it's depth slightly, it works.

Strange though, because it worked with the normal sort method.

[renderhjs]

otherwise you could write your own bubblesort function- can´t be so difficult

[Fall_X]

Yeah I've done that some years ago (in C if I'm not mistaking), but it can't be as fast as a native function.

[AfternoonDelite]

otherwise you could write your own bubblesort function- can´t be so difficult

mergesort would probably be your best bet if you're looking for efficiency.

A simple google search should lead you to the right direction, if you need to implement your own.

I was looking on google.. but I'm not really sure how to find how the methods are implemented in AS3.

I know that in Java.. the sort method.. uses mergesort.. and in order to do something like 'sorton'.. you just have to implement a Comparable interface and change the method to how you want to compare the objects.

And I know in PHP and PERL, you can also customize how arrays are compared through the sort method.

Not sure if that's possible in AS3.

[mr_malee]

http://linux.wku.edu/~lamonml/algor/sort/sort.html

has source code too

hmmm, me thinks a package is in order here

[BlinkOk]

what is the numeric value for the character "0"?

[Ray Beez]

Could it be because you forgot the spaces? IE:

surfaces.sortOn("depth",Array.DESCENDING | Array.NUMERIC)

[BlinkOk]

hehe. i would say a day late and a dollar short but it's a lot longer than that lol

[Ray Beez]

That's what she said

[BlinkOk]

har har lmao!