SkipGradients

[HansOlsson]

Split off from #4711

This is for the Modelica.Fluid.Examples.AST_BatchPlant.BaseClasses.TankWith3InletOutletArraysWithEvaporatorCondensor model used in Modelica.Fluid.Examples.AST_BatchPlant and is for the slanted pipe at the top:

This PR intends to get it to look as follows (this is also how it looks like in Dymola 2026x):

Supporting gradients on polygons would instead give (notice the odd gradients for the top-pipe; to me this just looks odd):

I assume the idea was something like the following (using paint) - but that requires gradients along the axis of polygons, which seems quite difficult to support:

[maltelenz]

Doesn't it just require rotation, or am I misunderstanding the problem?

Example model:

model RotatedGradient
  annotation(
    Icon(
      coordinateSystem(extent = {{-100, -100}, {100, 100}}),
      graphics = {
        Polygon(origin = {-100, -25}, fillColor = {0, 0, 255}, fillPattern = FillPattern.HorizontalCylinder, points = {{0, 100}, {200, 70}, {200, 50}, {200, 50}, {0, 80}, {0, 100}}),
        Polygon(origin = {-26.277, -37.037}, rotation = -10.471, fillColor = {170, 255, 255}, fillPattern = FillPattern.HorizontalCylinder, points = {{-78.894, 99.214}, {-70.024, 77.449}, {-50, 90}, {-32.628, 80}, {-15.687, 90}, {-3.137, 83.372}, {13.614, 91.606}, {28.046, 84}, {39.34, 89.724}, {54.725, 82.533}, {65.771, 89.724}, {80.625, 82.557}, {91.42, 95.999}, {89.933, 103.544}, {79.812, 88.469}, {68.619, 102.334}, {55.363, 90.654}, {41.223, 100.391}, {29.301, 89.41}, {13.181, 100.246}, {-2.824, 93.725}, {-14.118, 100}, {-32.628, 88}, {-50, 100}, {-68.861, 84.074}, {-71.939, 100.516}})
      }
    )
  );
end RotatedGradient;

and how it looks in System Modeler:

[HansOlsson]

Doesn't it just require rotation, or am I misunderstanding the problem?

I didn't think of that, but it is possible, one would then have to specify that the gradient is applied before the rotation - I don't know if that will cause weird effects for other cases. I'll forward that idea internally.

But since the gradient haven't worked as intended for years (or decades) I think just removing them as in this PR would work as well; they cannot be that important.

BTW: The idea was to rotate both of the polygons, and I hope we agree that something is needed.

[maltelenz]

The idea was to rotate both of the polygons

Right, I missed the cylinder.

I hope we agree that something is needed.

Yes, the current look is dreadful :)