Cannot create Intersection Point

Jan 20, 2010 at 6:00 AM

It seems that Live Geometry does not want to create an intersection point anywhere I would like it to create one. If two elements overlap (e.g. a line and a segment) Live Geometry does not allow to place an intersection point between these overlapping elements on the one hand and another element on the other hand.

Here's a sample file: You cannot create an intersection point between the arc and the bold segment...


<?xml version="1.0" encoding="utf-8"?>
  <Viewport Left="-12.3020833333" Top="5.0104166667" Right="12.3229166667" Bottom="-5.03125" />
    <PointStyle Size="10" Fill="#FFFFFF00" Color="#FF000000" StrokeWidth="1" Name="1" />
    <PointStyle Size="10" Fill="#FFFFFF00" Color="#FF000000" StrokeWidth="1" Name="2" />
    <PointStyle Size="10" Fill="#FFFFFF00" Color="#FF000000" StrokeWidth="1" Name="3" />
    <LineStyle Color="#FF000000" StrokeWidth="1" Name="4" />
    <ShapeStyle Fill="#FFFFFF00" Color="#00FFFFFF" StrokeWidth="1" Name="5" />
    <TextStyle FontSize="14" Color="#FF000000" FontFamily="Arial" Bold="false" Italic="false" Name="6" />
    <TextStyle FontSize="10" Color="#FF000000" FontFamily="Arial" Bold="false" Italic="false" Name="7" />
    <LineStyle Color="#FF000000" StrokeWidth="3" Name="8" />
    <FreePoint Name="A" Style="1" X="-5.2916666667" Y="-0.7291666667" />
    <FreePoint Name="B" Style="1" X="-0.6041666667" Y="3" />
    <FreePoint Name="C" Style="1" X="2.0208333333" Y="-2.0416666667" />
    <LineTwoPoints Name="LineTwoPoints6" Style="4">
      <Dependency Name="B" />
      <Dependency Name="C" />
    <LineTwoPoints Name="LineTwoPoints7" Style="4">
      <Dependency Name="C" />
      <Dependency Name="A" />
    <LineTwoPoints Name="LineTwoPoints8" Style="4">
      <Dependency Name="A" />
      <Dependency Name="B" />
    <Segment Name="Segment9" Style="8">
      <Dependency Name="B" />
      <Dependency Name="C" />
    <FreePoint Name="D" Style="1" X="1.75" Y="2.625" />
    <Circle Name="Circle11" Style="4">
      <Dependency Name="B" />
      <Dependency Name="D" />



Jan 20, 2010 at 6:23 AM

Yes, unfortunately it's a not implemented feature yet. I need a way to disambiguate between three possible combinations of figures to intersect.

I don't know how to design the UI as well - maybe just show a list of all figures under cursor and let user select any two??

Jan 20, 2010 at 7:03 AM

My proposal for UI

  • Show list of all figures under cursor in "Point by Coordinates" (or seperate) box.
  • Show them as description (FreePoint, LineTwoPoints, Circle, ...) plus name (A, LineTwoPoints7, Circle11,...)
  • Group overlapping figures in the box to indicate that intersection cannot occur between them
  • Let user choose intersection point by checking two figures
  • Default check the two "less restricted " figures, i.e. a line before a segment, a segment before a point etc.

I think most of the time it is pretty clear for the user which intersection to choose even if description plus name does not identify figures so well (you could change the names though before you make the intersection). Sometimes - as in my case - it is also not relevant which figure to choose for the intersection as long as the circle intersects with one of the straight figures.