Feature Request: transparency support in the SolderMask

[mundodisco8]

I'm trying to replicate OSH Park's After Dark look. KiCad does a relatively good job (as in, it supports "transparent" soldermaks, but copper is rendered in the same colour independently of it being exposed or not), but when I try to export a board with transparent soldermask with the exporter, and open it it Blender, playing with the transparency seems to have no effect. I don't know how feasible it is because it requires applying "copper" colour to all the unexposed copper and gold/HASL to all the exposed metal.

An example (left, OG purple OSH Park board, right, the alternative After Dark with clear mask)

(EDIT: my first post was a question about an error that no longer applies)
I have also been using KiBot a lot recently, and when trying to render a board with any value of alpha on the soldermask other than 100%, I get this error, which seems to point to "weird maths when trying to obtain the colour value of something with transparencies":

DEBUG:Executing: /usr/bin/blender -b --factory-startup -P /usr/local/lib/python3.11/dist-packages/kibot/blender_scripts/blender_export.py -- --format render blender --output /BlenderRender/Render.png /LED_Dimmer-3D_blenderTopSlanted.blend --scene /tmp/tmpt3il67eq.json /LED_Dimmer-blender_export.pcb3d (kibot - kiplot.py:156)
DEBUG:- Output from command: Blender 3.5.1 (hash e1ccd9d4a1d3 built 2023-04-24 23:31:15)
Traceback (most recent call last):
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/importer.py", line 205, in execute
    if (pcb := self.import_pcb3d(context, filepath)) == {"CANCELLED"}:
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/importer.py", line 375, in import_pcb3d
    setup_pcb_material(board_material.node_tree, images, pcb.stackup)
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/materials.py", line 87, in setup_pcb_material
    soldermask_inputs = {"Light Color": [*color, 1.0], "Dark Color":  [*(color * 0.2), 1.0]}
TypeError: can't multiply sequence by non-int of type 'float'
Error: Python: Traceback (most recent call last):
  File "/usr/local/lib/python3.11/dist-packages/kibot/blender_scripts/blender_export.py", line 434, in <module>
    main()
  File "/usr/local/lib/python3.11/dist-packages/kibot/blender_scripts/blender_export.py", line 410, in main
    bpy.ops.pcb2blender.import_pcb3d(**ops)
  File "/usr/bin/3.5/scripts/modules/bpy/ops.py", line 113, in __call__
    ret = _op_call(self.idname_py(), None, kw)
RuntimeError: Error: Python: Traceback (most recent call last):
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/importer.py", line 205, in execute
    if (pcb := self.import_pcb3d(context, filepath)) == {"CANCELLED"}:
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/importer.py", line 375, in import_pcb3d
    setup_pcb_material(board_material.node_tree, images, pcb.stackup)
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/materials.py", line 87, in setup_pcb_material
    soldermask_inputs = {"Light Color": [*color, 1.0], "Dark Color":  [*(color * 0.2), 1.0]}
TypeError: can't multiply sequence by non-int of type 'float'
Location: /usr/bin/3.5/scripts/modules/bpy/ops.py:113
Importing PCB3D file ...
Error: Python: Traceback (most recent call last):
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/importer.py", line 205, in execute
    if (pcb := self.import_pcb3d(context, filepath)) == {"CANCELLED"}:
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/importer.py", line 375, in import_pcb3d
    setup_pcb_material(board_material.node_tree, images, pcb.stackup)
  File "/usr/bin/3.5/scripts/addons/pcb2blender_importer/materials.py", line 87, in setup_pcb_material
    soldermask_inputs = {"Light Color": [*color, 1.0], "Dark Color":  [*(color * 0.2), 1.0]}
TypeError: can't multiply sequence by non-int of type 'float'
Location: /usr/bin/3.5/scripts/modules/bpy/ops.py:113

Blender quit

~where scene is ~

{
  "auto_camera_z_axis_factor": 0.85,
  "fixed_auto_camera": false,
  "lights": [
    {
      "energy": 10.020009999999997,
      "name": "kibot_light",
      "position": [
        -0.1666665,
        0.1666665,
        0.25025
      ],
      "type": "POINT"
    }
  ],
  "point_of_view": [
    {
      "rotate_x": -30,
      "rotate_y": 0,
      "rotate_z": 20,
      "view": "z"
    }
  ],
  "render": {
    "background1": "#505050",
    "background2": "#FFFFFF",
    "resolution_x": 200,
    "resolution_y": 200,
    "samples": 1,
    "transparent_background": false
  }

The renders work if opacity is set to 100 (fully opaque).

Because the errors point to the pcb2blender scripts, I thought about opening the issue here, but if you think I should move it to the KiBot side, close this and I will do it.

[set-soft]

Hi @mundodisco8 !

I think pcb2blender doesn't support transparency. The stackup file stores RGB, not RGBA (which KiCad can use).
I'm discarding the alpha channel (4th value) like this:

    def parse_kicad_color(self, string):
        if string[0] == "#":
            return KiCadColor.CUSTOM, self.parse_one_color(string, scale=1)[:3]
        else:
            return KiCadColor[string.upper()], (0, 0, 0)

The scene file isn't related to pcb2blender, and doesn't have any correlation with the PCB color.

Now for the error: are you sure you are using a fresh image? The code in /usr/bin/3.5/scripts/addons/pcb2blender_importer/materials.py around line 87 should be:

    if soldermask == "CUSTOM":
        color = Color(srgb2lin(stackup.mask_color_custom))
        soldermask_inputs = {"Light Color": [*color, 1.0], "Dark Color":  [*(color * 0.2), 1.0]}

The Color cast fixes the problem. You can see it here

[mundodisco8]

Man, Salva, you are omniscient!

Mi image was 10 days stale, tried with the latest and now it doesn't error out, so I'm happy with that. I guess now my question is a feature request 😄

[30350n]

Yeah, as @set-soft said, the error atleast should be fixed now on the master branch. Regarding transparency: This is something I'll have to look at once I find time to rework the materials (which could still take quite a while, sorry). That being said, you can always play around with the materials in Blender to achieve the look you want.