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# help : smooth motion when speed is slow

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hi, i'm making a pool game, and got a problem. when a ball's speed is very slow, the ball seem to move in an odd fasion. For example, when the ball's speed is 0.5 pixel per second, u'll see the ball stops for 2 seconds , and *jump* 1 pixel , and stop for 2 seconds again, and *jump* again. when the direction of the speed vector is nearly horizontal ( but now horizontal), the motion will be more funny. the ball will stop for a while , and then move right( suppose the speed vector directs to up-right), and stop again, and move right again. but some time later, it'll jump *up-right*, because the direction is not straight to right, and so the path of the ball is zigzag.(like below)
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i've tried a method that draw the ball two times. for example, the ball is moving from (0.0, 0.0) to (0.2, 0.0). firstly i draw the ball in (0, 0) without transparency. then, i draw the ball again, in (1, 0), with 20% transparency. but it's no use... please help if u know how to SMOOTH THE MOTION, and thanks in advance ! [edited by - wonyee on August 13, 2003 4:04:10 AM]

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Mmmh, you need sub-pixel accuracy methinks.

If you''re trying to draw a pixel at (0.4, 1) then you''d color both pixels (0,1) and (1,1), with (0,1) getting 60% of the color and (1,1) getting 40% of the color.

As the pixel (or collection of pixels) move from one to the next, it''ll ''fade'' positions, thus seeming smoother.

In theory, at least.

Superpig
- saving pigs from untimely fates, and when he''s not doing that, runs The Binary Refinery.
Enginuity1 | Enginuity2 | Enginuity3 | Enginuity4

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that''s what i''ve done before.however, i''m using alpha blending, so after drawing the ball for two times, it still looks transparent...maybe i should try using alternative method that the intersection part should looks opaque.

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Why are your pool balls only 1 pixel big?

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I'd suggest adding a stopping factor for speeds too slow to be noticeable (if the speed is less than a few pixels per second or so you could just stop the ball).

You might also increase the resolution, so that individual pixels aren't as visible.

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[edited by - The Senshi on August 13, 2003 3:28:30 PM]

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i''ve already set a stop factor. but billiards balls are impossible to stop suddenly. so stop fact cannot get rid of low speed...
increasing resolution is useless, i think. in fact, the resolution is already high.

Stonicus: my ball is 20*20 big.

there''s a game named "Cue Club". the billiards in that game can move with a very very slow speed, but the motion still looks very very smooth...admire...

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quote:
Original post by wonyee
that''s what i''ve done before.however, i''m using alpha blending, so after drawing the ball for two times, it still looks transparent...maybe i should try using alternative method that the intersection part should looks opaque.

This should work:

1. Clear a buffer to black (alpha=0).
2. Draw the centered ball (including alpha) using the appropriate alpha value.
3. Draw the offset ball (including alpha) using the appropriate alpha value with additive blending.
4. Draw the buffer on the screen with standard alpha-blending.

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Not that I've tried this or anything... but try having a few trailing "ghost balls" a la "mouse trails", each ball more faded than the next. Just an idea.

I was hoping for a sort of "Out of Context Melee" in this tread with such gems as "you need to make your balls bigger" or "my balls look weird when they move" or "thats why you're balls are clunky-looking," but alas I'll have to look elsewhere :-]

"Let me just ejaculate some ideas"

[edited by - LuckyNewbie on August 17, 2003 11:17:26 AM]

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"I was hoping for a sort of "Out of Context Melee" in this tread with such gems as "you need to make your balls bigger" or "my balls look weird when they move" or "thats why you''re balls are clunky-looking," but alas I''ll have to look elsewhere :-]"

Hehe, I can see it now "Sorry man but your balls are too damn small"

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