Draw debug lines with alpha less than 1.0 still appear opaque.

I’m running into an issue where I can’t debug draw lines with alpha less than 1.0. Does anyone know if this is a 4.1 specific problem or if there is a current work around?



I went into 4.1.1 and tested this with a debug line with an alpha of .9, but I am still seeing a line. Could you please send me a screenshot of the Draw Debug Line node and how it is being set up? Please include an image of the Line Color’s input. Any additional information may help with our investigation.


I am marking this question as answered for tracking purposes. If you have any more information to update the post with, it will be reopened.

Thank you

Hi , sorry for the delayed reply. The previous title of this question was poorly formed, I have edited it.

The issue is not that the line doesn’t show up (it still does with alpha less than 1.0 as you said), the issue is that it is always 100% opaque regardless of alpha value (transparency doesn’t seem to work on debug lines). Any info would be greatly appreciated.


Thank you for that information. I was able to reproduce the issue that you have described. It appears that Debug functions ignore the Alpha of their color by default. This may have been intentional, but I have put in a bug report to fix this since it is not conducive to all debugging workflows.

Thank you

Hey , I am using this function in my game for a laser sight for my weapons. Is there any update on using alpha with draw line? Also, you mention that is a debug function, what is an alternative way to draw a line via blueprint?

Hi UsefulEndymion,

This issue is from several years ago, and much of the editor has changed since this time. It would be best to post a question on the blueprint scripting or content creation section of the forums for further assistance on this.

Hello ! May i ask if the above issue was resolved? I’m running 4.20 and Alpha of the Trace Color is still 1…

And this is still a bug now!? Will this ever get fixed?

This is still a thing in 4.26.2. Don’t know about 4.27 or UE5