# Issue with opacity and enabling/disabling visibility of glyphs

**URL:** https://discourse.vtk.org/t/issue-with-opacity-and-enabling-disabling-visibility-of-glyphs/11258
**Category:** Development
**Created:** [April 19, 2023, 3:42pm UTC](https://discourse.vtk.org/t/issue-with-opacity-and-enabling-disabling-visibility-of-glyphs/11258 "2023-04-19T15:42:26Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![chrisiou](https://discourse.vtk.org/user_avatar/discourse.vtk.org/chrisiou/32/5546_2.png) [@chrisiou](https://discourse.vtk.org/u/chrisiou)
#### Post date: [April 19, 2023, 3:42pm UTC](https://discourse.vtk.org/t/issue-with-opacity-and-enabling-disabling-visibility-of-glyphs/11258/1 "2023-04-19T15:42:26Z")

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Hello everyone!

I am using vtkTensorGlyph for visualizing hundreds of thousands of voxeloid cells and vtkLookUpTable to change the color and the opacity of each glyph. I need to be able of enabling/disabling the visibility of some glyphs. To disable a specific glyph I am setting the alpha value of its rgba tuple to zero, but here I am facing a visualization issue. For alpha=0, the glyph instead of being transparent, it seems to take the color of the background and as a result, the above geometry disappears.

1. Is there some other way of enabling/disabling dynamically glyphs (or make them transparent)?
2. Can I adjust the opacity of a glyph another way?

the issue:

 ![tmp2](https://discourse.vtk.org/uploads/default/original/2X/9/967c633d90d70e7961031709a540c1a2889f3eb4.png)  
_Here, we have two different moments of the result in two screenshots. The blue and grey rectangles are glyphs. On the left, both glyphs have alpha=1. On the right, I have set the alpha value of the blue rectangle to zero and a hole seems to appear in the grey rectangle._