Posted by nacho on Feb 04, 2015; 6:00pm
URL: https://forum.world.st/Question-on-Morphic-drawOn-method-tp4803695.html

Hi,
I have the following question:
I want to draw a bouncing ball.
First thing I do is create a class:

EllipseMorph subclass: #Ball
        instanceVariableNames: 'position'
        classVariableNames: ''
        category: 'PBE-BouncingBall'


Then an initialization method that mostly do a super initialize.
Then the drawOn:  
 
drawOn: aCanvas
        aCanvas borderWidth:10; borderColor: Color green.


And finally a position method:

position: aPoint
        super position: aPoint.

position
        ^ position.


Finally in a Playground I do:

| aBall |

aBall := Ball new.
aBall position: ( 10@10 ).
aBall openInWorld.

But I get a red box with two crossing yellow lines.
What I'm missing?

Thanks in advance.
Nacho