Hi Javier,

First of all, RTGrapherBuilder has been obsoleted. Use RTGrapher instead.
I guess this is a problem with rounding with RTGrapherBuilder. With RTGrapher, I do not see this behavior.

For example:

-=-=-=-=-=-=-=-=-=-=-=-=
events := { 10.0 @ 1.0. 9.0 @ 2.0. 8.0 @ 3.0.
    7.0 @ 4.0. 6.0 @ 5.0. 5.0 @ 6.0.
    4.0 @ 7.0. 3.0 @ 8.0. 2.0 @ 9.0.
    1.0 @ 10.0. 0.0 @ 11.0}.

b := RTGrapher new.
b extent: 400 @ 200.

ds := RTDataSet new.
ds dotShape circle color: Color red.
ds interaction fixedPopupText: [ :e | e printString ].

ds points: events.
ds connectColor: Color blue.
ds x: [ :e | e y ].
ds y: [ :e | e x ].
b add: ds. 
b axisX noTick; noLabel.
b axisY noTick; noLabel.
b build.

b view add: ((RTLine new width: 0.02; color: Color yellow) edgeFrom: b view elements fifth to: b view elements last).
b view
-=-=-=-=-=-=-=-=-=-=-=-=

A deep zoom-in shows everything is okay:

Cheers,
Alexandre


On Jun 13, 2015, at 8:00 PM, Javier Pim��s <elpochodelagente@gmail.com> wrote:

Hi guys, I'm drawing a chart with roassal2 and just discovered that lines are not being drawn exactly as expected. Maybe this is a known problem? I'm running on a few months old pharo4beta image, in linux. Here I attach a screenshot corresponding to the code below. There are more evident examples but this one is easier to debug as it is a straight line made of many segments (zooming a bit you'll see the thin reference line and notice the blue line "bends"). Thanks for reading!

Cheers,
Javier

test
| b ds events |

events := { 10.0 @ 1.0. 9.0 @ 2.0. 8.0 @ 3.0.
    7.0 @ 4.0. 6.0 @ 5.0. 5.0 @ 6.0.
    4.0 @ 7.0. 3.0 @ 8.0. 2.0 @ 9.0.
    1.0 @ 10.0. 0.0 @ 11.0}.

b := RTGrapherBuilder new.
b extent: 400 @ 200.

ds := RTDataSet new.
ds dotShape circle color: Color red.
ds interaction fixedPopupText: [ :e | e printString ].

ds points: events.
ds connectColor: Color blue.
ds x: [ :e | e y ].
ds y: [ :e | e x ].
b add: ds. 
b axisXWithNumberOfTicks: events size.
^b build

<image.png>
-- 
Javier Pim��s
Ciudad de Buenos Aires

-- 
_,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:
Alexandre Bergel  http://www.bergel.eu
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