Intersection Point of 3 lines not engraving


#1

I am trying to etch a 3D Cube design on acrylic. Some of the points have 3 lines intersecting. For some reason, GFUI preview and the actual print seem to leave the intersection alone and no engraving is done.

Has anyone seen this? I tried different ways of creating the shape but no success. I am using AD.

Here’s the SVG
EXO-acrylic

Here’s the GFUI preview. notice the white corner.
45%20AM

This one is has the actual print on the bottom of the image.
The intersection did not get engraved so I stopped the print.
09%20PM


#2

Are there overlapping compound objects that come together at that point or have all the paths/objects been joined/combined?


#3

Yes, this diagnosis is most probably correct. The GF doesn’t follow the SVG specification correctly in the case of overlapping shapes with the same fill and no stroke. It should behave as you expect – if an area is painted twice, it’s painted. But that’s not how the GF sees it. Instead, it seems to treat the overlap as though it were a compound path, creating the areas where the engraving is missing.

Merging overlapping shapes together into one solves the problem. but you shouldn’t have to do that, Hopefully, this will get fixed at some point.


#4

Yes, they are overlapping objects as you’ve described, @marmak3261. How do you join the objects? When I add the curves they got joined weirdly.

this is what I ended up with :sob:


#5

I think I got it!

I expanded the strokes then joined the layers.


#6

Painted, sure… but how is it engraved? 2 passes? Because that’s what the instructions are, no?


#7

Not really. For raster engraving, it seems fair to say that the way it renders on screen or on paper should be the same way it renders on the Glowforge. At the end of the day, it’s a question of what color each pixel is, and overlapping two black shapes should produce black pixels, not white ones.

For vector operations, it’s a different story, and I do want to software to follow my instructions literally, including overlaps or duplicated lines.


#8

I thought we were specifically talking about vectors here - with mention of SVG specification and overlapping shapes consisting of a fill?

I haven’t tried overlapping rasters. What happens there?

And the (vector) path dropping on overlap would be a symptom of fill-rules, no?


#9

FWIW, here’s how it looks to me. In the SVG spec, “paint” is the term used to describe where a “color” (i.e., a mark of a certain sort) is to be made. In the case of printing on paper, the mark is rendered using ink or toner or whatever medium the technology uses. In the case of a screen, it’s pixels of light. In the case of the GF it’s laser pew-pew-pews delivered as a raster engrave. A closed path with fill but no stroke defines a “painted” area. Whether it’s ink, light or laser blasts, the process of rendering the SVG turns painted areas into pixels by rasterizing. And in all cases except the GF, the processes render overlapping, same-colored areas in the same way.

Among other things, the GF also handles overlapped areas of different “colors” differently than any of the other renderers I’ve looked at, but that’s another more complicated story. I really wish the GF rendering software tried harder to follow the SVG specification because doing so would make what comes out of the GF look a lot more like what the drawing in Inkscape or AI looks like on the screen or on paper.


#10

I’m probably out of my element here but is it actually rasterizing your vector “paint” area?

It seems if that were the case, the need for compound paths would be null. From my limited research, as far as laser cutting, if you want a donut, you make a compound path - not just put a white circle over your vector circle.


#11

Yes, the GF software in the “cloud” interprets a filled, closed path with no stroke as defining an area to be engraved. And since engraving is done as a raster, the process basically rasterizes it.

If you want a donut, you make a compound path from two paths – the path defining the hole inside the path defining the donut. The result is a shape that’s “painted” where the donut is, but not where the hole is. This will show up in the GFUI as a single operation that raster-engraves a donut.

If instead you tried to make a donut by stacking a white-filled path representing the hole on top of a bigger filled path representing the donut, it wouldn’t work. Doing it that way defines two areas that the GF will interpret as places to be engraved. One shaped like the whole donut, including the hole and the other shaped like the hole by itself.

To the GF, white is just another color, so what you’ll see in the GFUI is two engrave operations (because there are two colors – donut-colored and white). The first operation will engrave the whole donut, including where the hole should be, and the second will engrave the hole a second time.

Hope that helps make sense of this confusing topic.


#12

I’m glad you resolved it @tandanil! I’m going to close this thread - if the problem reoccurs, go ahead and post a new topic. Thanks for letting us know about this!

And thanks for the feedback @dehne1, I’ll make sure to pass it on to the team.


#13