Net Color change when changing pad transparency?

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Hi All,

I made an interesting observation when I was trying to figure out what happened to a custom color assignment I made to a USB net class… Apparently, when the pads are set to a transparency less than 100%, the color changes.
This was really confusing as I though that the net class was not configured correctly (since the color was not what I expected).

I’ve attached a video of this here:

This is on KiCad version: v9.0.1-ubuntu24.04.1, release build.

Has anyone else observed this?

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I’m not sure what you mean exactly, nor of what I’m seeing in your video. It looks like some pads have the layer color, while other pads are colored by net name. And when you change the transparency of a pad, you obviously get color mixing effects depending on whatever other objects are at the pad location. Are you referring to some specific pad in your video?

I do have a bit of a struggle with opacity settings. When objects become more transparent, you loose overall contrast and it’s more difficult to work on your project, and when opacity is too high, it obscures other objects at the same location.

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How do you make something partially transparent without showing some of the colour underneath and hence changing the apparent colour of what you are making transparent ?

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Color mixing is probably happening as the assigned color looks like it is mixing with the layer color… I don’t think this should be the case here since there are no other objects behind these pads on any other layer, and all internal layers have been disabled. The only mixed color should be the background, black…

Here is what I’m showing in the video, the two orange pads on the qfn package change from my assigned net class color orange to green/grey when I adjust the transparency slider (more transparent => green, then grey).

I would expect the pads to keep the assigned orange color but become transparent (the only color that should be mixed in my example is the background, black) rather than change to another color as it is difficult to identify which pads are part of a net class especially on high pin count BGAs or boards with multiple custom colors with some amount of transparency.

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I was focusing on both the blue and the red pads, got confused and sort of skipped the two orange pads (21 and 22 of the QFN).

Orange is a weird color, it triggered a memory of this video from “Technology connections” https://www.youtube.com/watch?v=wh4aWZRtTwU

I do not use net colors myself. Is this phenomena (mostly) limited to orange, or do you also see it with other colors? This can help in narrowing down of whether it’s really due to orange, or if it may be related to some bug.

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Great video, thanks for sharing! I agree orange isn’t the best choice…

Actually from what I can see, the issue is with all custom colors mixing with the layer color that the object is on. I’m not sure if this was an intentional change in version 9 or if this is a bug. I don’t recall this issue in earlier versions.

I fully expect colors to mix with transparency… But it’s not obvious what the function is for mixing colors of objects with it’s own layer color.