[vtkusers] newbie question - drawing a line!

[Sylvain Jaume]

Hi Anusha,

Did you allocate memory for your cells?
You could do this:

line Allocate [expr 1 + $numPoints]
line InsertNextCell $numPoints
for {set i 0 } { $i <  $numPoints} { incr i } {
    line InsertCellPoint $i
}

Cheers,
Sylvain

Anusha wrote:

> Hi,
>
> I'm trying to draw lots of raypaths on a 3-D model I've created by 
> plotting a lines joining up the multiple points which define these 
> paths.  I am sure it is a very trivial thing to do and that I'm making 
> a basic mistake somewhere but have been grappling with it for a while 
> and but can't seem to to make it work so any help/suggestions would be 
> much appreciated!  Am I on the right track - should I be trying to 
> turn the set of points into cells or should my data be defined as 
> lines in the data file to begin with?
>
> Many thanks!
> Anusha
>
>
> My data set is a set of x,y,z grid points and looks like...
>
> # vtk DataFile Version 2.0
> Ray paths
> ASCII
>
> DATASET POLYDATA
> POINTS 143088 float
> 21.3300 50.9900 -0.0241
> 21.3300 50.9900 -0.0241
> 21.3300 50.9900 -0.0328
> 21.3300 50.9900 -0.0327
> ....etc
>
>
> and this is the chunk of code I've been attempting to make work (but 
> get an error when trying to get the output of the vtkPolyData "rays" 
> in the vtkPolyDataReader.)
>
>
>
> vtkPolyDataReader raysReader
> raysReader SetFileName "rays.vtk"
>
> vtkPolyData rays
> vtkPoints points
> vtkCellArray line
>
> set numPoints [[raysReader GetOutput] GetNumberOfPoints]
>
> for {set i 0 } { $i <  $numPoints} { incr i } {
>     set val [[raysReader GetOutput] GetPointData]
>     points InsertPoint $i $i $val
> }
> rays SetPoints points
> points Delete
>
> line InsertNextCell $numPoints
> for {set i 0 } { $i <  $numPoints} { incr i } {
>     line InsertCellPoint $i
>     ptIds[1] =
> }
>
> rays SetLines line
> line Delete
>
>
> vtkPolyDataMapper mapRays
>   mapRays SetInput [rays GetOutput]
> vtkActor raysActor
>   raysActor SetMapper mapRays
>
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