CGX with new colormaps

Dear CalculiX users,

CalculiX GraphiX with a few new colormaps and ‘cmap’ command is available. Please, follow link for details and downloads:


Great! Thanks for adding these.

For completeness, a blog post by Mathworks on the same topic:

on why they switch to their Parula scheme (quite similar to the Viridis by the way)

By the way, one my colleague asked to implement also a grayscale colormap. How do you think, is it needed?

Probably the most requested are Jet/Rainbow (just because… is the standard, not for being the better, customers and bosses want the standard!), grayscale could be usefull for printing in a black/white printer, but in fact in more than 20 of doing FEA and having it available on several postprocessors, never did the change (or seen in colleagues reports), normally a report is done to be clear on screen and then printable. Even when I see a pdf or any other document on screen with grayscale colormap, I ask myself why they don’t do in colors? Yes, is for printing, but nowdays most documents are seeing in screens.

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Agree 100% with @SergioP


Grayscale maps of color are usable for printable book tutorials or examples. Switching between viewable ebook and CCX/CGX or any pre/post-pocessor windows are not effective when someone’s in steep learning curve.

Stilll a good ideas to include these features.

Thank you,

Yes, for some people standard colormap is not perfect, for example:

And may be is the better way add more contrast colormap.


I try to do some comparison for stress contour plot. Jet/turbo setting look too smooth, not given greater insight in range separation. Looking another post processing programs, are interesting.


ABAQUS use jet/turbo approach with removing two grades of dark colours at peak/lowest range (red & blue) with black lines for element edge . FEMAP has different approach, similar to classic with minor modification & add light blue colour, using blue lines for element edges.

Is possible to add User Defined color plot of results without recompiling CalculiX GraphiX CGX?

Thank you,


Adding a user defined colormap is a very good idea. And I think it’s possible to program user defined colormaps to be defined via .cgx configuration file in user’s home folder.

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hi @imirzov

i look out to some papers regarding to color maps categories, there’s grouped by three type : qualitative, sequential & diverging. available two of these type has been implemented (qualitative: classic & turbo, sequential: viridis, inferno) but no one implemented for diverging type (e.g known as cool to warm). an examples, diverging type of color maps can be useful to separated between compression & tension areas clearly, a neutral will be in white color ranges. mostly used in post-processing of limited/brittle materials e.g reinforced concrete beams in CalculiX examples.


it may complete enough if one of diverging type of color maps been implemented, hope it’s possible for next updates of CGX. thank you much.




i tried to implement new colormap for RedBlue and Gray using modification of extGL.c file from this links. however i’m not have any experiences compiling CGX under windows. how do i test and contribute?




Dear xyont,

thank you for contributing CalculiX! As I remember, Rafal Brzegowy can compile CGX under Windows. Please, pay attention, that compiling for Linux is much easier. I did only Linux compilations and followed official documentation.

You can send your CGX contributions directly to Mr. Klaus Wittig. Just send him extGL.c file.

dear Imirzov,

i look previous CGX colormap setting, seems it had changes at max number of color intensity from 32 (original) to 256 (community). but it’s clear since i downloaded the newest source code of CGX officially.

alright, i will finalized modification and try to contact him directly.

i upload above files to GitHub (links) do you have a time and kindly would to test and take a screenshot to shown the code is working properly? thanks before


You had mistakes. I’ve committed fixed version to your github repo. Now it works fine.


By the way, you can contribute to CGX repo in CalculiX group on the GitHub:

Please, do not hesitate to create pull requests. This repo is slightly outdated and needs to be updated with versions 2.18 and 2.19. Would you like to do it, xyont?

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so many thanks I.Mirzov for testing and fixed.

as my past comment, i’m not familiar with GitHub. not a really programmer also, just an ordinary user with a small background in C & Python. but has experienced in implementing of code/regulation of structural design algorithm procedures.

hope someday i can contribute to CalculiX to have a specific modules in structural member design (steel & reinforced concrete) as Strand7 or Ansys does.

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Oo! I would like that as I have been doing modeling concrete bridge rails for ultimate strength. Compression only is good, but compression nonlinearity comes into play sometimes. Other material types in CCX can be non-linear, but seem to be symmetrical between compression and tension stresses.

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there’s also available material type for concrete plasticity e.g Compression Only, Modified Mohr Coulomb, Drucker Prager w/o Cap or even a damage type material with Mazars (require MFront linked). however, the purpose of structural member design are in deferent task. pre-estimate of concrete reinforcement required of beam element and check capacity strength ratio due to load cases for column element or steel members.

nonlinear analysis is good and it can give insight the behavior, but may took too long to ran and complicated, sometimes or frequently the convergence issue are hard to detect. it’s better approach to study validated an analytical approach based on code regulations and designing some condition it does not covered.

No code regulations apply to bridge rails* in the US except crash tests, a very expensive way to design, probably necessary for flexible rails, but not rigid or relatively rigid rails that do not deform too much on the macro scale. The rail itself does not need to survive as the design level is a very rare instance. Analysis usually done with LsDyna by test centers associated with universities and state governments. Ls Dyna too expensive otherwise. Work with LsDyna has recently established loads for the critical crash tests, but is too computationally (and software) expensive for most problems.

My work has focused on reducing the amount of reinforcing needed as we are shifting to stainless steel, and simplified methods of evaluating existing rails, and also to effects on more distant parts of the structure (expansion joints in deck overhangs, bearings, etc.). The real behavior tends to be dependent on the amount of softening, and for effects distant from impact, the spreading of the impulse over time.

I agree Mohr-Coulomb should capture most of the effects on the concrete itself except tension stiffening. An asymmetric (WRT tension/compression) stress/strain would be easiest to use. Since for most of my career (started in the 60’s) I have not had access to high end FEM. I am using Mecway to ease the transition into FEM for more highly detailed models.

*Similar case with vehicular impacts on other bridge elements, except in that case the target is to prevent structure collapse, as it is in earthquake design or evaluation. The state I work in is not very earthquake prone, so I am not much involved in that. Also often plastic methods can be used.

Michael L. McMullen PE