Point Sprites

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bojkar 101 Mar 18, 2007 at 21:05

Hello everyone.
I have problem with point sprites. I set point size :

glPointSize(20);

But this isn’t work. When camera is far all is ok but when is near particles are very very small. What is wrong?

thanks

6 Replies

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Rubicon 101 Mar 18, 2007 at 23:10

not sure about ogl, but they probably suffer the same problem as with D3D since they’re both just interfaces to the same hardware.

You can’t have infinite sized particles. I think there’s a caps bit in D3D (I ignore it myself) that tells you how big this is, but I think its 64x64 pixels on most cards. Even if that’s wrong, the limit is way short of fullscreen sizes.

It may even be small enough so a texture applied to one will fit entirely within the texture cache. Just guessing here.

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juhnu 101 Mar 19, 2007 at 15:01

I would recommend you to use just normal triangles instead of point sprites - the point sprite support across different hardware is not robust enough.. waste of time.

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Rubicon 101 Mar 19, 2007 at 16:30

Actually, for particles I’d recomend point sprites!

You never want them to go full screen because of fill-rate issues anyway, and the bandwidth saving of sending 1 vertex instead of 4 or 6 will increase your performance by around that factor (ie 4x as many point sprites, give or take.) in any real-world situation.

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bojkar 101 Mar 19, 2007 at 18:30

ok I use point sprites because is the most fast. But why points change self size?

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juhnu 101 Apr 13, 2007 at 17:48

@Rubicon

Actually, for particles I’d recomend point sprites! You never want them to go full screen because of fill-rate issues anyway, and the bandwidth saving of sending 1 vertex instead of 4 or 6 will increase your performance by around that factor (ie 4x as many point sprites, give or take.) in any real-world situation.

Sorry, but I can’t resist asking if you still would recommend people to use them? ;)

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Rubicon 101 Apr 13, 2007 at 22:26

lol, you’re on that list too huh.

I still am using them on the 360, but no - on PC they truly suck. Kill them all. Shame really as they’re techinically brilliant but the driver writers clearly don’t give a shit about em. :wallbash:

(My recent follies do seem a bit bizarre as I’ve always used them with no problems at all, yet all of a sudden they don’t seem to work on hardly anything.)