fillarea creates black area

[doutriaux1]

import vcs
x=vcs.init()
o = vcs.createfillarea()
xs = [-70.0, -66.0, -62.0, -58.0, -54.0, -50.0, -46.0, -46.0, -50.0, -54.0, -58.0, -62.0, -66.0, -70.0]
ys = [97.40004179212772, 99.24051369561087, 99.64501380920407, 99.50791666242807, 99.25809764862053, 98.72724999321828, 97.86243057250978, 66.1760279867384, 78.08891693751016, 84.6064443588257, 75.83586128552756, 54.88270839055378, 33.08841943740845, 32.207757042513954]
o.x = xs
o.y = ys
o.worldcoordinate = [-70,-35,30,100]
x.plot(o)

generates:

[doutriaux1]

why is there black?

[doutriaux1]

using a line produce the correct result:

[durack1]

@doutriaux1 even though it's wrong, the top image kinda looks like 3D.. Kinda cool

[jypeter]

Not much 3D. I have tried to shake my screen to see if the shadow was moving, but no result :p

[doutriaux1]

@danlipsa @aashish24 any progress on this? I ran into this again last week.

[doutriaux1]

went back all the way to commit: 3c70e0f bug was here.

At this commit vtk api changed and I can't get a working vtk

[doutriaux1]

@danlipsa @aashish24 I can reproduce this in pure vtk

import vtk

xs = [-70.0, -66.0, -62.0, -58.0, -54.0, -50.0, -46.0, -46.0, -50.0, -54.0, -58.0, -62.0, -66.0, -70.0]
ys = [97.40004179212772, 99.24051369561087, 99.64501380920407, 99.50791666242807, 99.25809764862053, 98.72724999321828, 97.86243057250978, 66.1760279867384, 78.08891693751016, 84.6064443588257, 75.83586128552756, 54.88270839055378, 33.08841943740845, 32.207757042513954]

N = len(xs)
pts = vtk.vtkPoints()
for i in range(N):
    pts.InsertNextPoint(xs[i],ys[i],0.)

polygon = vtk.vtkPolygon()
polygon.GetPointIds().SetNumberOfIds(N)
for i in range(N):
    polygon.GetPointIds().SetId(i,i)

polygons = vtk.vtkCellArray()
polygons.InsertNextCell(polygon)
polygonPolyData = vtk.vtkPolyData()
polygonPolyData.SetPoints(pts)
polygonPolyData.SetPolys(polygons)

mapper = vtk.vtkPolyDataMapper()
mapper.SetInputData(polygonPolyData)

actor = vtk.vtkActor()
actor.SetMapper(mapper)

renderer = vtk.vtkRenderer()
renWin = vtk.vtkRenderWindow()

renWin.AddRenderer(renderer)
renIter = vtk.vtkRenderWindowInteractor()
renIter.SetRenderWindow(renWin)

renderer.AddActor(actor)
renderer.SetBackground(.5,.3,.31)
renWin.Render()
renIter.Start()

Should I submit a bug on VTK site?

[doutriaux1]

reported there: https://gitlab.kitware.com/vtk/vtk/issues/17141

[danlipsa]

@doutriaux1 You cannot fill concave polygons in OpenGL. You'll have to split them in triangles.
https://www.opengl.org/discussion_boards/showthread.php/153256-How-draw-fill-non-convex-polygon-in-OpenGl
Do we need to add this functionality to VCS?

[doutriaux1]

yes! definitely! I ran into this twice in two weeks now. I'll take a closer look at your post and see if we can "hack" this.

[doutriaux1]

@danlipsa actually it was easy to make it work:

import vcs
x=vcs.init(bg=True,geometry=(300,300))
f = vcs.createfillarea()
xs = [-70.0, -66.0, -62.0, -58.0, -54.0, -50.0, -46.0, -46.0, -50.0, -54.0, -58.0, -62.0, -66.0, -70.0]
ys = [97.40004179212772, 99.24051369561087, 99.64501380920407, 99.50791666242807, 99.25809764862053, 98.72724999321828, 97.86243057250978, 66.1760279867384, 78.08891693751016, 84.6064443588257, 75.83586128552756, 54.88270839055378, 33.08841943740845, 32.207757042513954]
f.x = xs[::-1]
f.y = ys[::-1]
f.worldcoordinate = [-70,-35,30,100]
x.plot(f)

simply revert the vertices. I'll implement a patch soon. It's clockwise vs counterclockwise issue