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Scripts in Croquet

Tao asked for a "Tweak & Croquet" tutorial. I don't have time right now to actually write one, but here's some sample code anyway.

Using scripts is easy and useful, even without the Tweak GUI. Just use #startScript: to run some method as a script. Inside a script, you can use loops and anything you like, just throw in a wait to account for time. Like, to animate the color of a frame, you could use this method (just add it to your TeapotMorph):
animateColorFor: aFrame
    [
        0 to: 360 do: [:hue |
            aFrame material color: (Color h: hue s: 1.0 v: 1.0).
            self wait: 0.01]
    ] repeat
This changes the color every 10 ms, and you can start it from the initializeDefaultSpace method:
    self startScript: #animateColorFor: withArguments: {someFrame}.
Here is something that does not loop forever, but finishes after one cycle:
jump: aFrame
    | v g |
    v := 0@1@0.
    g := 0@-0.05@0.
    [aFrame translation y >= 0] whileTrue: [
        aFrame translation: aFrame translation + v.
        v := v + g.
        self waitTick.
    ].
    aFrame translation: 0@0@0
Here we wait for the end of the frame - waiting is essential, because we do want to change the position only once in a frame. This can be run in response to a pointer click like this:
    self startScript: #jump: withArguments: {someFrame} when: {someFrame. #pointerDown}.
Or, if you wish, you could make a Tweak button for it. Here's the whole initializeDefaultSpace method doing it all:
initializeDefaultSpace
    | space cube |
    space := TSpace new.
    space addChild:  TLight new.
    self makeFloor: space fileName:'floor.BMP'.

    cube := TCube new.
    cube material: TMaterial new.
    space addChild: cube.

    self startScript: #animateColorFor: withArguments: {cube}.

    self startScript: #jump: withArguments: {cube} when: {cube. #pointerDown}.

    self initializeTweakWorld: [
        | button |
        button := CButton new.
        button label: 'Jump'.
        button openAt: 100@100.
        self startScript: #jump: withArguments: {cube} when: {button. #fire}.
    ].

    ^space
Hope that helps ...
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Comments

Philipp said…
Very nice code snippets, a good starting point.
April 26, 2005
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