[Optimising] Bullet theory (collsion checks)

I reckon it's mainly the rendering that's slowing everything down. Iopred's Particle System could handle this many bullets and collisions without even batting an eyelid. I know this because I'm using it for collision detection with 100 arrows vs 100 soldiers and getting pretty much full framerate. With your amount of bullets against only a single ship, you could definitely get rid of the lag using the Particle System class.

EDIT: Here's a link to it:

http://board.flashkit.com/board/show...1&postcount=33

50000 tests is quite a lot. If you think about realistic game with 250 enemy bullets vs 1 ship the difference between fastest and slowest method is about 3 milliseconds. I still think every collision detection script takes much less time then simply moving the 250 bullets and updating the screen.

Thanks for all the replies guys :) I was only expecting a few.

Anyway, I'm about to start work on a bitmap data version of the bullets to see how it runs so i will let you know how things work out.

Thanks.

Ali

hi,

your "burreto teori" looks great so far. i`m also working on a manic bmp shooter,.

the way i try to reduce hit checks is similar to squize`s way. i just check if bullet, enemy or player are in the same cell, and then hitTest them(allthough i might have to try , if it really is faster with a simple bounding box hitTest, to get the cell they are in,since i do it by coordinates, right now).

either way, its faster, because there is no constant hitTesting and the loops are much smaller.

im pretty amazed by iopreds particle class, damn fast...have to check it out

anyway, if you find a good and speedy alternative, it would be great if you could share it with us.

have fun

Chris

vengeance, that things amazing, im gonna have to figure out how it works some time...im really bad at doing so though

I only spent a few seconds browsing through iopreds code, but I can't quite work out why it runs so quickly. It seems to me he’s just attaching bitmaps to movieclips and then moving them as normal... how is that any different to just attaching a movieclip with a bitmap already in it?

By the way, I should have said this before, but I’m not actually having any speed issues at the moment, this thread was just because I wasn’t sure which of two methods were faster for collision detection. I still want to make it as speedy as possible though, so I’m continuing to look into bitmap collisions.

Ali

The consensus is to use circle testing (without sqrt) for collision, it was proved just a page back to be the fastest by quite a lot, and for round bullets, it seems like the perfect choice.

The Movieclip+BitmapData renders faster than Movieclips with bitmaps in them because normal MC's bitmaps are treated as square vectors with a bitmap fill. BitmapData is cached and is faster to draw.

So use Movieclip + BitmapData for display, and circle testing for collision and you'll be on the right track.

Thanks mate, that what I needed to know :).

Ali

Quote:

---

Originally Posted by iopred

The consensus is to use circle testing (without sqrt) for collision, it was proved just a page back to be the fastest by quite a lot, and for round bullets, it seems like the perfect choice.

The Movieclip+BitmapData renders faster than Movieclips with bitmaps in them because normal MC's bitmaps are treated as square vectors with a bitmap fill. BitmapData is cached and is faster to draw.

So use Movieclip + BitmapData for display, and circle testing for collision and you'll be on the right track.

---

have you experimented at all with bitmap.hitTest method, as another alternative the the other collision methods you tested....and if so, I was interested at your thoughts about it......whether you'd use something like that or not....

paul.

I haven't tested the speed of it, so I'm going purely on assumptions. But theres no way I see, that the bitmap hitTest would be faster than a simple bounding box hitTest. It would be nice if someone implemented it into Webgeeks testing fla however.

Quote:

---

Originally Posted by iopred

I haven't tested the speed of it, so I'm going purely on assumptions. But theres no way I see, that the bitmap hitTest would be faster than a simple bounding box hitTest. It would be nice if someone implemented it into Webgeeks testing fla however.

---

I did that (Flash8):

Bitmapdata.hitTest Test
Iterations: 200
Tests: 250
Total Tests: 50000
Hits: 50000
Misses: 0
Duration (milli): 509-545

Note: it did just run bitmapdata.hittest function 50000 times with bitmapdata object in hero and in enemy objects (25x25 px). It did not use the idea I talked about earlier about using 1 screensized bitmapdata object for all enemies.

Quote:

---

Originally Posted by tonypa

Note: it did just run bitmapdata.hittest function 50000 times with bitmapdata object in hero and in enemy objects (25x25 px). It did not use the idea I talked about earlier about using 1 screensized bitmapdata object for all enemies.

---

wow....even still, when compared with similar F8/AS2 tests by webgeek, it's clearly almost twice as fast as any of the other methods....even the simple bounding box hitTest....that's GREAT news!!! :D :) :)

now, if we could only get coordinates returned for the collision with that method...

paul

I got completely contrary results to tonypa.


HT - Shape to Point Test
Iterations: 200
Tests: 250
Total Tests: 50000
Hits: 0
Misses: 50000
Duration (milli): 721

HT - Bounding Box to Point Test
Iterations: 200
Tests: 250
Total Tests: 50000
Hits: 200
Misses: 49800
Duration (milli): 599

HT - Bounding Box to Bounding Box Test
Iterations: 200
Tests: 250
Total Tests: 50000
Hits: 1800
Misses: 48200
Duration (milli): 833

Math - Circle to Circle Test
Iterations: 200
Tests: 250
Total Tests: 50000
Hits: 1600
Misses: 48400
Duration (milli): 599

HT - Bitmap to Point Test
Iterations: 200
Tests: 250
Total Tests: 50000
Hits: 50000
Misses: 0
Duration (milli): 2571

The bitmap hittest was well the slowest, even checking a point, and even when you have 100% misses:

HT - Bitmap to Point Test
Iterations: 200
Tests: 250
Total Tests: 50000
Hits: 0
Misses: 50000
Duration (milli): 2505

i really wish Adobe would do somethinhg about the rendering in flash.

we are living in the age of broadband Adobe, how's about intergrating directX or openGL, i'd download an extra 10mb

bitmapData could be so much better

bastards

Quote:

---

Originally Posted by iopred

I got completely contrary results to tonypa.

---

Which Flash version you used? I noticed that in Flash9 Alpha the bitmapdata hittest results were much slower then in Flash8. Which could be because the code is not AS3 VM compatible. Or something....

Quote:

---

Originally Posted by mr_malee

we are living in the age of broadband Adobe, how's about intergrating directX or openGL, i'd download an extra 10mb

---

Mac version has OpenGL rendering, and it's far slower than the PCs in my school's IT room. No idea why.

Quote:

---

Originally Posted by tonypa

Which Flash version you used? I noticed that in Flash9 Alpha the bitmapdata hittest results were much slower then in Flash8. Which could be because the code is not AS3 VM compatible. Or something....

---

It was Flash 8, but in the Flash 9 player.

Just checking in on the shooter gang. Don't see any news, so I think monday we can have another demo of http://www.deusx.com/xlr

Just gotta decide which 3-4 levels to show.

Don't worry mate, "Project Soon"* is on it's way :)

Be cool to see what everyone else is up to.

Squize.

* Working title

Cool, looking forward to it :)


Just an update on the bitmapData stuff while I'm here. I’ve spent a few hours converting my engine to support bitmapData and things seem to be running ok for now. Progress is very slow at the moment with bullet theory though because I want to make it so perfect that I never seem to spend any time progressing with the game :p. I’ve started to get things rolling now though and I'm confident I will get it finished sooner rather than later.

Ali