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50 sprites

Posted by SpiceWare, in Space Rocks 16 April 2012 · 3,900 views

Hit Reset to get start the "game". Select returns to the rainbow screen.

Hit Fire to advance levels. The starting number of asteroids will be the first 1-2 digits of score(leading 0 is blanked out). This can be from 4-12.

Every 2 seconds an asteroid will break into two asteroids. This will occur until all the asteroids are small. The middle 2 digits of the score will be how many asteroids are flying around.

Push joystick in any direction to speed things up and break an asteroid every half second.

Last 2 digits of score are flicker level.
0 = no flicker
1 = 30 Hz
2 = 20 Hz
3 = 15 Hz
4 = 12 Hz


Started with 4 asteroids, broken up into 8 asteroids (10 total sprites w/saucer and ship)
Attached Image

Started with 12 asteroids, broken up into 48 asteroids (50 total sprites). Flicker varies from 2 to 4. This is a worse-case sprite count as I doubt it would ever occur during an actual game.
Attached Image

ROM
Attached File  spacerocks20120417.bin (32KB)
downloads: 193

Source
Attached File  spacerocks20120417.zip (278.01KB)
downloads: 182

"robotron test"
Attached File  spacerocks75.bin (32KB)
downloads: 194
Attached File  spacerocks100.bin (32KB)
downloads: 182




Hmm - just saw a minor glitch. Occasionally a left moving asteroid will wrap to about position 100 instead of 160, and thus span only 2/3 of the screen. This doesn't affect the flicker test.
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Nice work - Asteroids is one of my favourite arcade games. I don't think I've seen so many independently positioned sprites on the 2600 before. The flicker really isn't too bad either. However, I do prefer the look of the vectors from the arcade version, rather than solid asteroids. Thomas managed to duplicate this look nicely in his Asteroids DC+ hack.

Chris
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How about a true vetorial game? You made a demo time ago that display vetorial lines at 60 hz using the arm chip to calculate.

You have a b/w screen but with "unlimited" numbers of objects, also it's a recent technique that never has been done in a finished Atari 2600 game.
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Thanks - mine too.

I think it'll be a run-time option. I'll need solid asteroids for my sprite collision routines as they are pixel perfect, so's a risk that a shot could jump inside a vector asteroid w/out triggering the collision. I'll set it up so a vector image uses their corresponding solid image during collision detection.
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Screenshots look awesome! For me it throws an ARM error on start with Stella 3.4.1 with DPC+ selected in Game Properties. I see there's a newer Stella out there (even a .deb for my specific Ubuntu version) and will try that later.

When I see 50 sprites on the screen at once, what immediately comes to mind is a screen full of grunts in Robotron. One of your Frantic test builds reminded me a lot of that already, plus the walls. Don't know if it would be possible, but it seems more possible now than it did before you started doing all this work.
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Yeah, that was fixed in version 3.5 of Stella.

It's possible, but flicker would be way worse. Here the sprites are moving around on their own paths, keeping them fairly well vertically separated so the two players can be reused to draw everything. In Robotron the enemy converges on the player, meaning everything tends to go into the same vertical band. A worse case scenario of 50 overlapping sprites would have a flicker rate of 24, or 2.5 Hz.
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How about a true vetorial game?

Sorry - I missed your post before, it must gone up while I was replying to cd-w.

That's an idea, though my routine was limited to something like 96x200. That could probably be expanded using Galaxian's RESPn trick, but I'm not interested in pursuing it at as I plan to return to work on Frantic after making a few fixes in this demo (like the left-moving asteroid bug in the first comment).
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How about a true vetorial game? You made a demo time ago that display vetorial lines at 60 hz using the arm chip to calculate.You have a b/w screen but with "unlimited" numbers of objects, also it's a recent technique that never has been done in a finished Atari 2600 game.

Like 2600 Meteoroids (Starpath Supercharger Suicide Mission Prototype)?
2600 Meteoroids


Wonderful demo, SpiceWare!!!
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In Robotron the enemy converges on the player, meaning everything tends to go into the same vertical band. A worse case scenario of 50 overlapping sprites would have a flicker rate of 24, or 2.5 Hz.


Well, even in the arcade version of Robotron there are plenty of glitches when you have enemies overlapping each other, and their animation is pretty jerky. On the 2600, if they're overlapping and all roughly the same color it may not be a bad effect, and it may be possible to minimize that by having their "follow the player" routine favor the horizontal over the vertical. But I won't have time to test that anytime soon, unfortunately.
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I added 2 builds that restrict the asteroids to the top 75 and top 100 scan lines to simulate sprite concentration that would occur in Robotron.

With 75 the rate tended to be 6 (sprites are displayed 1 out of every 7 frames - my flicker rate number is how many frames a sprite is not displayed), though I did see instances of 10.

With 100 the rate tended to bounce between 4 and 5.

For comparison, Pac Man has a rate of 3.

0 = no flicker
1 = 30 Hz
2 = 20 Hz
3 = 15 Hz
4 = 12 Hz
5 = 10 Hz
6 = 8.6 Hz
7 = 7.5 Hz
8 = 6.7 Hz
9 = 6 Hz
10 = 5.5 Hz
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