How do I make a sprite move in a sine curve?

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Trisect Development

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Posted: 11th May 2012 12:24 Edited at: 11th May 2012 12:43

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If I want to move a sprite around a sine curve like a moving in a eight laying down. How do I do that?

In Tier1.

I do something like this but it does not look like a 8.

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SetSpritePosition(MyObject_6.SpriteNumber, XSin, 600 + (Sin(Xsin)*100))

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Hodgey

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Posted: 11th May 2012 12:42

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Here's a small code snippet.

+ Code Snippet

setVirtualResolution(getDeviceWidth(), getDeviceHeight())

spr = createSprite(0)

x# as float = 0.0
y# as float = 0.0
speed# as float = 2.0
freq# as float = 100.0

do
    x# = x# + speed#
    y# = sin(x#) * freq#
    if x# > getDeviceWidth() then x# = 0
    setSpritePosition(spr, x#, y# + getDeviceWidth()/2)
    print(x#)
    sync()
loop

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Trisect Development

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Posted: 11th May 2012 12:46 Edited at: 11th May 2012 12:49

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Looking good Hodgey.

And if I want it to go back to the left like moving in an eight laying down??

I do something like this but its jerky

+ Code Snippet

        If LoopDirection = 1
            SetSpritePosition(MyObject_6.SpriteNumber, XSin, 600 + (Sin(Xsin)*100))
            XSin = XSin + 1
            If XSin >= 800
                LoopDirection = -1
            EndIf
        EndIf
        If LoopDirection = -1
            SetSpritePosition(MyObject_6.SpriteNumber, XSin, 600 + (Sin(-Xsin)*100))
            XSin = XSin - 1
            If XSin <= 10
                LoopDirection = 1
            EndIf
        EndIf

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Hodgey

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Posted: 11th May 2012 13:20

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I was able to do this but the 'reflection' is a bit jerky. It's more like a bounce than a smooth figure 8. I just negate the sin function when going 'backwards'. If you need something more elaborate then I can keep trying, but it might get a bit complex.

+ Code Snippet


setVirtualResolution(getDeviceWidth(), getDeviceHeight())

spr = createSprite(0)

x# as float = 0.0
y# as float = 0.0
speed# as float = 2.0
freq# as float = 100.0

reflect as integer = 0 // acts as boolean

do
    if reflects = 0
        x# = x# + speed#
        y# = sin(x#) * freq#
    endif

    if reflects = 1
        x# = x# + speed#
        y# = -sin(x#) * freq#
    endif

    if x# > 360.0
        reflects = 1
        speed# = speed# * -1
    endif

    if x# < 0
        reflects = 0
        speed# = speed# * -1
    endif


    setSpritePosition(spr, x#, y# + getDeviceWidth()/2)

    print(x#)
    sync()
loop

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Trisect Development

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Posted: 11th May 2012 13:28

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Thanks Hodgey!

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baxslash

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Posted: 11th May 2012 13:43

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It's simpler than you think:

+ Code Snippet

setVirtualResolution(getDeviceWidth(), getDeviceHeight())
spr = createSprite(0)
speed# = 100
do
    time# = timer()
    x# = getDeviceWidth()/2 + sin(time#*speed#)*200
    y# = getDeviceHeight()/2 + sin(time#*speed#*2)*100
    setSpritePosition(spr, x#, y#)
    sync()
loop

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Hodgey

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Posted: 11th May 2012 13:51

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Very nice baxslash! It amazes me what you can do with a timer.

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baxslash

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Posted: 11th May 2012 14:03

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The first few lines in my loop almost always look like this these days:

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time# = timer()
ft# = getFrameTime()

I use them for all sorts of things

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Impetus73

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Posted: 11th May 2012 14:06

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baxslash, you should make a small guide on the use of timers, if you have not already.

----------------
AGK user - novice
Did Amiga / AMOS programming in the 90's, just started programming again with AGK.

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baxslash

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Posted: 11th May 2012 14:15

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Around halfway down. For some reason it's not been added to the new news area yet...
http://www.thegamecreators.com/pages/newsletters/newsletter_issue_111.html

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Trisect Development

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Posted: 11th May 2012 14:17

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Nice job baxslash as allways.

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Impetus73

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Posted: 11th May 2012 14:23

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I knew I had seen something about it, but I could not recall if it was your excelent work, so it was.

----------------
AGK user - novice
Did Amiga / AMOS programming in the 90's, just started programming again with AGK.

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baxslash

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Posted: 11th May 2012 14:27

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Glad to help!

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