[vtk-developers] Bug introduced in OpenGLContextDevice2D::DrawPoly

[Eric E. Monson]

Hey Marcus,

I'm getting closer to tracking down the problem I've been having with my parallel coordinates plots drawing some of the lines wrong when color-by-array is on: I think it's something that was introduced with commit 59f3d82d9183d7b3c5f014dfc7a3159562e0e494 when you "Split out the OpenGL 2 code from legacy OpenGL" and reworked some of the routines.

Attached are a Python test and two images, before and after that commit (16061efb087a07b22235d5cd1417b0cfe871218c used for "before"). It's like the color mapping has been shifted by a couple of indexes so that some parts of line segments are being drawn with the color that should be for later segments. (I know that's a bad description, but look at the images and see if you can see what I mean...)

I'll start taking a look at the code pretty soon, but I wanted to point it out in case an idea pops into your head right away.

Thanks,
-Eric

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