How to render glyphs on triangle normals with VTK #tcl #vtk #visualization

vtk_triangle_normals_glyph.tcl

# This example shows how to manually construct triangle cell using unstructured grids 
# and display its surface normal.
#

package require vtk
package require vtkinteraction

# Create an unstructured grids containing a triangle cell.
vtkPoints trianglePoints
  trianglePoints SetNumberOfPoints 3
  trianglePoints InsertPoint 0 0 0 0
  trianglePoints InsertPoint 1 1 0 0
  trianglePoints InsertPoint 2 .5 .5 0
vtkTriangle triangle
  [triangle GetPointIds] SetId 0 0
  [triangle GetPointIds] SetId 1 1
  [triangle GetPointIds] SetId 2 2
vtkUnstructuredGrid triangleGrid
  triangleGrid Allocate 1 1
  triangleGrid InsertNextCell [triangle GetCellType] [triangle GetPointIds]
  triangleGrid SetPoints trianglePoints
vtkDataSetMapper triangleMapper
  triangleMapper SetInput triangleGrid
vtkActor triangleActor
  triangleActor SetMapper triangleMapper
  [triangleActor GetProperty] SetDiffuseColor .3 1 .5

# Create an arrow glyph to represent the surface normal for the triangle cell.

vtkDataSetSurfaceFilter triangleCellDataSetSurfaceFilter
  triangleCellDataSetSurfaceFilter SetInput triangleGrid

vtkPolyDataNormals triangleCellNormals
  triangleCellNormals SetInputConnection [triangleCellDataSetSurfaceFilter GetOutputPort]
  triangleCellNormals ComputePointNormalsOff
  triangleCellNormals ComputeCellNormalsOn
  triangleCellNormals SplittingOff
  triangleCellNormals FlipNormalsOff
  triangleCellNormals ConsistencyOn
  triangleCellNormals AutoOrientNormalsOn

# Generate the point normal at the center of the triangle cell
vtkCellCenters triangleCellNormalsAtCellCenters
  triangleCellNormalsAtCellCenters SetInputConnection [triangleCellNormals GetOutputPort]

# Specify the shape and location of the surface normal glyph
vtkArrowSource arrowSource

vtkGlyph3D arrowGlyph
  arrowGlyph ScalingOn
  arrowGlyph SetScaleFactor 0.7
  arrowGlyph SetVectorModeToUseNormal
  arrowGlyph SetScaleModeToScaleByVector
  arrowGlyph OrientOn
  arrowGlyph SetSourceConnection [arrowSource GetOutputPort]
  arrowGlyph SetInputConnection [triangleCellNormalsAtCellCenters GetOutputPort]

vtkDataSetMapper arrowGlyphMapper
  arrowGlyphMapper SetInputConnection [arrowGlyph GetOutputPort]

vtkActor glyphActor
  glyphActor SetMapper arrowGlyphMapper

# Create the usual rendering stuff.
vtkRenderer ren1
vtkRenderWindow renWin
  renWin AddRenderer ren1
  renWin SetSize 300 150
vtkRenderWindowInteractor iren
  iren SetRenderWindow renWin

ren1 SetBackground .1 .2 .4

ren1 AddActor triangleActor
ren1 AddActor glyphActor

ren1 ResetCamera
ren1 ResetCameraClippingRange

renWin Render

# render the image
#
iren AddObserver UserEvent {wm deiconify .vtkInteract}
iren Initialize
wm withdraw .