Roku Developer Program

[_creare_]

When I run the below code my roku has a black screen and eventually crashes.
I think the issue is the while true loop but I haven't figured out how to have a wait or sleep

I found sleep() but it did not do anything to stop the crash
Neither did a thing with wait(0,port) (I may have implemented it wrong)

Here are all my files, their names and locations are designated by "FILE pkg:/*****/****.***"

File pkg:/components/Pong.brs

    Function init() 'Function is run when XML is parsed

        m.top.backgroundColor = "0xabc123FF" 'Set background color to black

        m.top.backgroundURI = "" 'Set background URI (image) to empty so background color displays

        m.Ball = m.top.findNode("ball") 'Sets pointer to TopLabel node to adjust fields

        m.Ball.blendColor="0xFFFFFFFF"

        ballXPos = CreateObject("roFloat")

        ballXPos = 0

        bounceDirection = CreateObject("roInt")

        bounceDirection = 0

        while true

            if ballXPos > 1920

                bounceDirection = 1

            end if

            if ballXPos < 0

                bounceDirection = 0

            end if

            if bounceDirection = 0

                ballXPos = ballXPos + 50

            else

                ballXPos = ballXPos - 50

            end if

            m.Ball.translation = [ballXPos, 50]

        end while

    end Function

File pkg:/components/Pong.brs

<?xml version="1.0" encoding="UTF-8"?>

<component name="Pong" extends="Scene" >

<script type="text/brightscript" uri = "pkg:/components/Pong.brs"/>

    <children>

        <Label id="testLabel" 

            text="SCREENSAVER!"

            width="1920" 

            height="1080" 

            horizAlign="center"

            vertAlign="center"

            font="font:LargeBoldSystemFont"

        />

    <Poster

        id="ball"

        uri="pkg:/images/blackcircle.png"

        width="400"

        height="400"

        translation="[0,0]"

    />

    </children>

</component>

FILE pkg:/source/main.brs

sub Main()

    screen = createObject("roSGScreen") 'Creates screen to display screensaver

    port = createObject("roMessagePort") 'Port to listen to events on screen

    screen.setMessagePort(port)

    scene = screen.createScene("Pong") 'Creates scene to display on screen. Scene name (AnimatedScreensaver) must match ID of XML Scene Component

    screen.show()

    while(true) 'Uses message port to listen if channel is closed

        msg = wait(0, port)

        if (msg <> invalid)

            msgType = type(msg)

            if msgType = "roSGScreenEvent"

                if msg.isScreenClosed() then return

            end if

        end if

    end while

end sub

[sanity-check · Accepted solution]

Yeah, you can't do stuff like that on the UI thread - i.e. not in any visual component.

https://developer.roku.com/en-gb/docs/developer-program/core-concepts/threads.md

You could create a 'Task' node which updates its ballXPos field on an interval, and have the UI code watch that field and update the x position when it changes.

Or if you don't want to bother with tasks, you can use a Timer node set to repeat and run your game loop code in that:

https://developer.roku.com/en-gb/docs/references/scenegraph/control-nodes/timer.md

[_creare_]

Thank you! This works really well!

A few things about their example for others who might find this thread :
Make sure to change the "extends" thing from "Group" to "Scene"
And you can also set the timer to really low values like 0.01