Smooothness

[NakedApe]

I was just messing around with a particle fountain. Sometimes the program runs smoothly, but if I change the _limit a little it can become hurky-jerky. Like the below seems to do great at 60 or 80 FPS, though runs less smoothly at 50 or 70. Is it my laptop?  Is smoothness in graphics always a dance between run-speed and the number of pixels that items move per cycle?  I'm curious how this could be made to run smoothly at various _limits. Any thoughts or insights appreciated!

Code: (Select All)

OPTION _EXPLICIT

SCREEN _NEWIMAGE(1280, 720, 32)

RANDOMIZE TIMER: _MOUSEHIDE

_DELAY .25: _SCREENMOVE _MIDDLE



TYPE particle

    x AS SINGLE

    y AS SINGLE

    Vx AS SINGLE

    Vy AS SINGLE

END TYPE



DIM AS INTEGER c

DIM AS particle p(200)



start:

c = -1

DO '

    c = c + 1 '                                   init particles

    p(c).x = _WIDTH / 2

    p(c).y = c * -5 - 140

    p(c).Vx = 0

    p(c).Vy = 3 + (RND - RND) / 4

LOOP UNTIL c = UBOUND(p)



DO

    c = -1

    CLS

    _LIMIT 60

    DO '                                            move em

        c = c + 1

        p(c).x = p(c).x + p(c).Vx

        p(c).y = p(c).y + p(c).Vy

        IF p(c).y > 20 AND p(c).y < 26 THEN p(c).Vx = (RND - RND) / 1.75 '  only change em once

        IF p(c).y > 14 THEN p(c).Vy = p(c).Vy + .06 '  a little gravity

    LOOP UNTIL c = UBOUND(p)



    c = -1

    DO '                                            draw em

        c = c + 1

        PSET (p(c).x, p(c).y), _RGB32(255)

    LOOP UNTIL c = UBOUND(p)



    _DISPLAY

    IF p(200).y > _HEIGHT + 140 THEN GOTO start

LOOP UNTIL _KEYDOWN(27)

SYSTEM