Axes in images generated by Trixi2Img are inverted and unlabeled

[efaulhaber]

The axes seem to be inverted in every image. For example here is the generated image for the output of

Trixi.run("examples/2d/parameters.toml", n_steps_max=1, initial_conditions="initial_conditions_linear_x",
    boundary_conditions="boundary_conditions_linear_x", periodicity=false)

in ParaView:

and in Trixi2Img:

Furthermore the axes should be labeled in Trixi2Img (especially for 3d data).
We should also think about adding the slice plane to 3d images, so it's always clear at which plane we are looking.

[efaulhaber]

I dug a little and found that this is due to the contourf function from Plots itself.
When the plot is built from a matrix the first matrix dimension corresponds to the y-axis while the second matrix dimension corresponds to the x-axis.

If I transpose the matrix first, I will get the correct image.
I am not sure if this is the correct fix here, but I created a pull request that does exactly this.

[ranocha]

Thanks for catching that! Yeah, it's always annoying to have to switch dimensions in such plots. I've left some comments in our Slack conversation.

[efaulhaber]

Thank you. So the correct fix would be to call contourf with match_dimensions=true. I will create a new pull request once trixi-framework/Trixi2Img.jl#18 is merged as this PR is based on it (axis labels for 3d slices require different logic).