Does imagesoverlap vs imagescollide still count?

Blitz3D Forums/Blitz3D Beginners Area/Does imagesoverlap vs imagescollide still count?

Tobo	(Posted 2010) [#1]

Dear all,

For the umpteenth time, i'm trying to learn BB again and have come across collision detection. The book I'm reading suggests using imagesoverlap rather than imagescollide for speed. I understand why the science would favour imagesoverlap, but in this day of super speedy computers, if you're writing a simple space invaders or platform game, would the performance really take such a hit?

I know I could suck it and see (which I will) but I wanted to know what you guys think.

Toby

_PJ_	(Posted 2010) [#2]

The speed difference is most likely neglible on the majority of current computers (specifically gaming machines.

Much ofthe documentation for Blitz relates to typical users with a preferred resolution around 800x768, possibly still requiring 16-bit colour depth and perhaps with limited graphical hardware acceleration and features.

I suppose it's mainly relevant for determining your target audience.

Ross C

(Posted 2010) [#3]

Nope. 2D graphics acceleration hasn't at advanced, if all, in the past 10 years?

This piece of code demonstrates a verrrrrrrrrry slight difference, over 10,000,000 calls.

I use a delay so the application setup doesn't affect the time. I get a difference of 75 milli-seconds over 10,000,000 calls. So thats... .0000075 milli-second difference between the two commands.

Takes about 10 seconds to run.

Graphics 800,600
SetBuffer BackBuffer()

Delay 2000 ; delay for setup

Global image = CreateImage(50,50)
SetBuffer ImageBuffer(image)
For loop = 0 To 1000
	Color Rnd(0,255),Rnd(0,255),Rnd(0,255)
	Plot Rand(0,ImageWidth(image)),Rand(0,ImageHeight(image))
Next

SetBuffer BackBuffer()


Global timer = MilliSecs()

For loop = 0 To 10000000

	If ImagesCollide(image,Rnd(0,750),Rnd(0,550),0,image,Rnd(0,750),Rnd(0,550),0) Then
		b = 1
	End If
	
Next

Global time_collide = MilliSecs() - timer


timer = MilliSecs()

For loop = 0 To 10000000

	If ImagesOverlap(image,Rnd(0,750),Rnd(0,550),image,Rnd(0,750),Rnd(0,550)) Then
		b = 1
	End If
	
Next

Global time_overlap = MilliSecs() - timer


Text 0,0,"Time taken for 10,000,000 ImagesCollide() - "+time_collide+" millsecs()"
Text 0,10,"Time taken for 10,000,000 ImagesOverlap() - "+time_overlap+" millsecs()"

Flip

WaitKey

Tobo	(Posted 2010) [#4]

That's probably the most concise answer I've ever received (even the wife's "I do" was more measured!).

I got about 90 difference on mine. I guess I don't need to worry too much.

Many thanks, guys.

Tobo