Bug? - Drawing draft circle against ImagePlane makes all lines disappear

[benjaminwharton]

Open the file (in v0.18) and try drawing a draft circle. Immediately any lines/circles disappear, as if obscured by the ImagePlane. If you then rotate the view slightly they become visible again.

Can anyone confirm this?

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15938 (Git)
Build type: Release
Branch: master
Hash: acdd4b097bbaf6d94bc09cf38f25924bd5d3e778
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: French/France (fr_FR)

[kisolre]

It looks like the faces are drawn first, then imageplane and then edges:

ImagePlane_DraftCircle.JPG (120.1 KiB) Viewed 889 times

Code: Select all

OS: Windows 8.1
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16093 (Git)
Build type: Release
Branch: releases/FreeCAD-0-18
Hash: 690774c0effe4fd7b8d2b5e2fb2b8c8d145e21ce
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: Bulgarian/Bulgaria (bg_BG)

[GeneFC]

When all the features are at the exact same z-level the result is often undefined. Just move the image plane in the -z direction a small amount and the other features will become visible.

Gene

[kisolre]

When all the features are at the exact same z-level the result is often undefined...

You are correct. But here it looks more like scale issue. The image is 106m x 117m and the small movement of -10mm that OP set is negligeble while rendering and gives that error. Here I have it set to -93 and just one scrollwheel zoom moves the circle from over to under the image:

CircleOver.JPG (96.02 KiB) Viewed 858 times

CircleUnder.JPG (96.25 KiB) Viewed 858 times

Maybe DraftRectangle.texture will work better but here I have bug with it so can't try.

[GeneFC]

It could be a scale issue, but it is not clear there is a bug. Instead there seems to be a simple display limitation. Under some conditions of z-shift and viewing tilt I was able to get "z-fighting", which means the display function treats the ImagePlane and the Circle to be in the same plane. If I set a much larger z-offset for the ImagePlane then there is no problem.

There may be some adjustment in the preferences, but I do not know where. In any case the effect is probably only visual, although confusing.

The screenshots below were all made with the same z-offset.

Capture.PNG (14.71 KiB) Viewed 840 times

Capture2.PNG (12.29 KiB) Viewed 840 times

Capture3.PNG (27.72 KiB) Viewed 840 times

Gene

[Willem]

Be sure that in Properties the make face function is false

Schermafdruk van 2019-03-21 15-43-41.png (344.77 KiB) Viewed 832 times

[kisolre]

Be sure that in Properties the make face function is false
Schermafdruk van 2019-03-21 15-43-41.png

The problem is that if there IS a face it is sometimes drawn under the the image plane even if it should be over it.

[benjaminwharton]

Thanks all for the responses.

It seems like it might then be the result of precision issues since I'm using such a large scale for the ImagePlane.