DrawLine+Scale: thickness bug..

[abakoboParticipant]

Issued on github too

Monkey

[crayon-5cba8d889e04a117553990 inline="true" ] #Import "<std>" #Import "<mojo>" Using std.. Using mojo.. Class MyWindow Extends Window Field zoom:=25.0 Field radius:=0.3 Field x:=9.3 Field y:=9.2 Method New( title:String="Simple mojo app",width:Int=640,height:Int=480,flags:WindowFlags=Null ) Super.New( title,width,height,flags ) End Method OnRender( canvas:Canvas ) Override canvas.BlendMode=BlendMode.Opaque canvas.Scale(zoom,zoom) canvas.DrawCircle( x,y,radius ) canvas.Color=Color.Black canvas.LineWidth=radius*2.0 'this line is supposed to be as thick as the circle... canvas.DrawLine(x,y,x+2.0,y) canvas.Color=Color.White canvas.DrawCircle( x,y+2.0,radius*4.0 ) canvas.Color=Color.Black canvas.LineWidth=radius*2.0*4.0 'this line is supposed to be as thick as the circle... canvas.DrawLine(x,y+2.0,x+2.0,y+2.0) End End Function Main() New AppInstance New MyWindow App.Run() End

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[crayon-5cba8d889e04a117553990 inline="true" ] #Import "<std>" #Import "<mojo>" Using std.. Using mojo.. Class MyWindow Extends Window Field zoom:=25.0 Field radius:=0.3 Field x:=9.3 Field y:=9.2 Method New( title:String="Simple mojo app",width:Int=640,height:Int=480,flags:WindowFlags=Null ) Super.New( title,width,height,flags ) End Method OnRender( canvas:Canvas ) Override canvas.BlendMode=BlendMode.Opaque canvas.Scale(zoom,zoom) canvas.DrawCircle( x,y,radius ) canvas.Color=Color.Black canvas.LineWidth=radius*2.0 'this line is supposed to be as thick as the circle... canvas.DrawLine(x,y,x+2.0,y) canvas.Color=Color.White canvas.DrawCircle( x,y+2.0,radius*4.0 ) canvas.Color=Color.Black canvas.LineWidth=radius*2.0*4.0 'this line is supposed to be as thick as the circle... canvas.DrawLine(x,y+2.0,x+2.0,y+2.0) End End Function Main() New AppInstance New MyWindow App.Run() End

[/crayon]

[Mark SiblyKeymaster]

Ok, a fix for this is now up at github in develop branch – you just need to grab latest canvas.monkey2.

The problem was due to DrawLine using ‘normal’ DrawLine if LineWidth<1. But with scaling, this isn’t always correct.

So I’ve changed the check to LineWidth<=0 (LineWidth now defaults to 0 too) so any >0 linewidth will make mojo use it’s ‘fancy’ DrawLine, ie: draw rects instead of lines.

I’ve also added a LineSmoothing property to Canvas (defaults to false) to control the fake antialiasing of lines. If LineSmoothing is true, lines drawn with LineWidth>0 will be antialiased-ish.

This actually produces pretty convincing antialiased lines with LineWidth>=2 and less than about 5. Less than 2 and the line starts to ‘break up’ noticably, greater than 5 and the anitaliasing ‘fudge’ starts showing! I’ve added a little linetest banana showing this.

I’ve also tweaked draw circle/oval/ellipse so primtives are better ‘centered’ and hopefully more symmetrical.

There are still issues with line end points, but I think this is getting there!

[abakoboParticipant]

Great! Thanks.
I use them for 2d physics debug draw so perfection is not mandatory! A bit of consistency when scaling is a good point, I hope it’s not slowing down the process..

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