pcb-rnd knowledge pool


HID: layer group transluency config

layer_alpha by Tibor 'Igor2' Palinkas on 2017-12-31

Tags: howto, translucency, translucent, layer, layers, transparent, hid, rendering, screen, alpha

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Abstract: It is possible to change how translucent layers are on the screen, when hardware accelerated rendering is used.

  Imported from the mailing list archives.

Comparing the gtk2+opengl rendering to the lesstif+xrender rendering, they do the same:

(The same happens with any other group as well, silk was just an example.)

The translucency between different groups will not happen with gtk2+gdk and lesstif-without-xrender.

controlling the translucency

When Keith Packard fixed up our gtk+gl earlier this year, he foreseen different translucency preferences by users, so he added a feature called layer alpha. It's a floating point number, between 0 and 1 in the conf tree, under appearance/layer_alpha ; the default value is 0.7 I think. As of r13749, the lesstif HID also supports this.

The simplest way to try it out is from the command line:

./pcb-rnd foo.lht -c appearance/layer_alpha=1

If you find the right value, you can put it in any of the config files the same way you did with the invis-color.

It is also possible to change it on the fly, using the following action:

conf(set, appearance/layer_alpha, 0.2)

If you are using the gtk+gl HID, it is possible t change this value from the preferences window (Config PoV tree, appearance, layer_alpha).