Possible bug (unexpected result) applying a Conic Mesh to an Arc

[Stefan Zientek]

Using the 0.92pre3 Pre-Release I've tried creating a mesh by drawing a circle and applying a 3 by 3 conical gradient to it. In doing so I have observed some unexpected behaviour.

I've attached a file showing the circle modified into an arc - with a slice taken out of it - which I've tried to colour as if like a ripple of colours from the original centre of the circle.

Changing the colour on the nodes on the horizontal radial line affects the colour gradient above the sloped line (on the other side of the slice) rather the adjacent area to the actual node. It does not seem possible to blend another colour in the region below the horizontal line - so that in this example one might have rings of concentric colour. There are also no nodes on the sloping radius of the given arc.

Is this as it should be?

Stefan Zientek
22 November 2016

[Tavmjong Bah (tavmjong-free)]

This is a weakness in the mesh gradient interface. The conical mesh gradient in this case covers the full circle (the pie shaped piece in the path is clipping the mesh). This mesh gradient is wrapped so that one side is touching the "opposite" side. Were the two sides touch (in this case at the horizontal line) there are two sets of nodes on top of each other. One can select nodes from both sets by using a "rubber-band" selection.

If one created the arc before the mesh, the mesh would not be wrapped completely around and node selection would be more straight forward.

[prkos (prkos)]

To illustrate what Tav explained I moved the mesh nodes so they don't sit on top of each other, so you can better understand what is happening. I also created the circle cut out and an arc and applied the mesh to them, so you can better see how conical gradient works. When conical mesh area (not the same as path area! applied to your example!) covers full circle some mesh nodes aren't visible because there are mesh node pairs positioned at the same location.

We need the "open" conical mesh examples in Mesh gradient docs to make it clear from the start.