How to set Netclass color to "Transparent" in KiCad 7?


My schematic looks like this:


I’m supposed to be able to set the Netclass color to Transparent but how?



Preferences > Preferences > Schematic Editor > Colours > New Theme.

Kicad themes are read only.
When you create a new theme, the colours showing will carry over to your new theme, so you will now have the Kicad theme under a new name so it may be modified.

Next, get to your color picker window, and alter the transparency with the Value slider on the RHS. 255 = solid, 0 = transparent.

Your new theme will carry over to the PCB editor list, however You will still need to select it there.

Thanks jmk,

I think you’re saying that I need to create my own theme because Kicad themes are read only. I assume I’m using the default theme. Does that mean I can’t select Net Classes in Schematic Setup

click on the Color for the Earth netclass and make it transparent?

If I do click on color and move the right-hand slider to zero, what I showed before changes to this:


and it won’t simply Undo. I have to go back into the netclass color and change it there.

The manual says: “Setting the color to transparent will use the theme’s default wire/bus color for the netclass”.


You cannot change anything to do with the color until you use your own theme. As I mentioned above, your theme can be exactly the same as Kicads, you just need to change the name so it is no longer “Kicad Default (read-only)”

Independent from the “transparency”-question: your schematic-wires look way too big.
Remember there are two netclass-parameter dialogs:

  • schematic setup–>netclasses–>wire thickness (your picture above) sets the wire-thickness in the schematic view.
  • board-setup–>netclasses–>track width sets the track width for the the real board.

Thanks. I thought I was setting PCB track widths in the schematic. I get it now - I only create and assign the netclasses there.

The color in your screenshot is already transparent. Transparent is represented by the checkerboard shown at the bottom.

I have a suspicion that you can’t set a net class to transparent at the moment.
For some reason I have two different color pickers.
When I go to:

  1. Click on wire.
  2. Edit it’s properties.
  3. Click on the color (with it’s checkerboard patern).


Then I get this color picker:

When I go to: Schematic Editor / File / Schematic Setup / Project / Net Classes, and then click on the color checker board:

Then I get this color picker:

In this second color picker, the opacity slider on the right side of the window is missing.
I don’t know whether this is a bug or intentional.

Also, in either of the color pickers, I can select a color in the round HSV area, but when I click or drag around in the RGB “cube” nothing happens. This also seems like a bug.

I am also not sure about the meaning of the checkerboard. I guess it means some “default color” instead of “transparency”.

Application: KiCad Schematic Editor x86_64 on x86_64

Version: 7.0.6-7.0.6~ubuntu20.04.1, release build

	wxWidgets 3.2.1
	FreeType 2.10.1
	HarfBuzz 6.0.0
	FontConfig 2.13.1
	libcurl/7.68.0 OpenSSL/1.1.1f zlib/1.2.11 brotli/1.0.7 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh/0.9.3/openssl/zlib nghttp2/1.40.0 librtmp/2.3

Platform: Linux Mint 20.3, 64 bit, Little endian, wxGTK, xfce, x11

Build Info:
	Date: Jul  7 2023 02:32:25
	wxWidgets: 3.2.1 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.71.0
	OCC: 7.5.2
	Curl: 7.88.1
	ngspice: 38
	Compiler: GCC 9.4.0 with C++ ABI 1013

Build settings:


The cube is for placing a color with known RGB ratio. Use the + & - buttons attached to each primary color. The end result shows in the circle.
Move the point on the circle, result shows on cube with RGB ratios beneath.
Needs a bit of practice to understand.

Agree, and I cannot set opacity with Net Class.

Top is a wire with opacity 100%
Middle is a wire with opacity setting to 16%
Bottom, set with net class. Can’t opacify :slightly_smiling_face:

I’m not sure about peoples understanding of color generation but for those not sure:

RGB (red, green & blue) are the additive colors (primary). This is how a computer monitor works - use a magnifying glass to see the screen pixels.

YCM (yellow, cyan & magenta) are the subtractive colors (secondary). This is how your printer works - see the ink.

If the Color Picker was for printing, it would have the white lines to the other three corners. ie. the Y, C & M corners.

I expect that both methods work. You click on a color in either the RGB cube or HSV circle, and then you should be able to refine your choice with the plus and minus buttons.

You also can’t drag the little squares in the RGB cube

No, you type in the ration number or use the + & - (or both) under the cube, and see the result in the circle.
OR you move the little square in the circle, and see the ratio of RGB mix that creates that color, in the squares under the cube.

The cube is just a graphical representation (visual aid) of the RGB color ratios underneath it. The small squares in the cube are not slider controls.

To be honest, I think the Color Picker would be less confusing if the cube was omitted.

Sorry, I should have made my above post a little clearer.

I was giving this some thought.

I can’t think of a reason to make a Bus or Wire (that is all that Net Classes cover) transparent. Transparency would make reading difficult.

Anyone else care to comment?

I agree it’s difficult to find a reason for this.

Maybe I have a use case where it’s marginally useful…

I am currently working on a passive backplane.
Just a bunch of connectors parallel.
J1 is a “specialized” connector on the left (which is going to be used in the daughterboard projects) and for the others, I just threw in a generic 40p connector. All the wires are just drawn straight through the connectors. Any which way it goes is fine for me, as it’s mostly to get the netlist done, and there is no significant info on that side of the schematic, except to indicate that all connectors are connected in parallel.

Just maybe, using transparency could make things a bit clearer in a case like this.
But I guess any improvement would be pretty marginal at best.

I am quite happy with how this schematic turned out.

  • Drawing the wires through all the connectors was just a case of holding [Ins] to repeat.
  • Adding extra connectors is pretty much the same.
  • Just drop an extra connector on the parallel wires, and it auto connects with junction dots.
  • The wire labels automatically change netclass with (power wires are thicker).
  • Wire labels are sorted in 4 columns of signal types, which makes sorting and making changes easy.

Drawing this as a bus would be horrible. Managing all the wire labels and bus breakout for each connector separately… (and doing it again during maintenance (adding connectors, changing pin assignment). Just juck.

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And you have to move the slider next to the circle, the circle is HSV HS on the circle V is on the vertical slider.

The “Value” slider beside the circle I think would be better described as “Luminance” and the “Saturation” as “Colour Saturation”.

It depends on what it actually is . . . :wink:

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Brightness = Luminance in my dinosaur days.

I cut my teeth as an engineer in the early 70’s working on CTV design using “Colour Difference” rather than “RGB Drive”

Colour Difference had four inputs to a CRT. Luminance, Red, Green & Blue.

RGB Drive replaced Colour Difference by the mid 70’s with IC development and manufacturing costs.

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I am also quite a dinosaur concerning colors.
I’m happy if I click on some color and see a vaguely similar color in my CAD program.
And if the “cube” does not work, then I try the circle.
I don’t care about “RGB” versus “HSV”, and that is why I won’t even attempt to make a bug report. I just noticed a discrepancy between those two GUI areas, that’s all.


I think the opacity omission was deliberate.

It is bad enough trying to read a five year old faded schematic without it also being pre-faded. :rofl:

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