Painting contacts fails for specific configuration

[fhagemann]

When updating the configuration files to avoid deprecation warnings, I stumbled across a possible bug (?) in the painting algorithm.

Minimum working example

Configuration file: public_CGD_config_new.txt --> rename to public_CGD_config_new.yaml
(Sorry, but files that end with .yaml cannot be uploaded easily here)

using SolidStateDetectors
T = Float32

sim = Simulation{T}("public_CGD_config_new.yaml")
simulate!(sim, convergence_limit = 1e-6, refinement_limits = [0.2], verbose = false)
evt = Event([CartesianPoint{T}(0,2e-3,0)])
simulate!(evt, sim, Δt = 1e-9, max_nsteps = 10000)
signalsum = sum(broadcast(wf -> abs(wf.value[end]), evt.waveforms))

@info signalsum
@assert isapprox( signalsum, T(2), atol = 1e-3 )

It looks like the second contact does not get painted onto the grid.

Trouble shooting

The problem seems to be this geometry in the difference of the contact with id: 2:

- box:
    widths: [0.5, 10, 10]
    origin: 
      x: 4.75

This does not happen when widths: [0.6, 10, 10], when òrigin: 4.8, or when T = Float64.
So, I am assuming that this is connected to some kind of rounding error (?)

The geometry in the initial configuration file public_CGD_config.yaml also works perfectly and looks like this:

- box:
    x: 
      from: 4.5
      to: 5
    y: 10
    z: 10

[lmh91]

I don't think the issue is the paining. At least not alone.
Some debugging information I found out so far:

I disabled the painting and compared your config file with the example config file:

T = Float32
sim1 = Simulation{T}("public_CGD_config_new.yaml")
sim2 = Simulation{T}(SSD_examples[:CGD])
p_det = plot(sim1.detector);

apply_initial_state!(sim1, ElectricPotential, Grid(sim1, max_tick_distance = 1u"mm"))
apply_initial_state!(sim2, ElectricPotential, Grid(sim2, max_tick_distance = 1u"mm"))

plot(
    plot(sim1.point_types, y = 0, size = (600,600)),
    plot(sim2.point_types, y = 0, size = (600,600)),
    size = (1000, 400)
)

I compared the geometries of the first contact:

    @test sim1.detector.contacts[1].geometry.a.hX ==
          sim2.detector.contacts[1].geometry.a.hX
    @test sim1.detector.contacts[1].geometry.a.hY ==
          sim2.detector.contacts[1].geometry.a.hY 
    @test sim1.detector.contacts[1].geometry.a.hZ ==
          sim2.detector.contacts[1].geometry.a.hZ
    @test sim1.detector.contacts[1].geometry.a.origin ==
          sim2.detector.contacts[1].geometry.a.origin
    @test sim1.detector.contacts[1].geometry.a.rotation ==
          sim2.detector.contacts[1].geometry.a.rotation

    @test sim1.point_types.grid.x == 
          sim2.point_types.grid.x 
    @test sim1.point_types.grid.y == 
          sim2.point_types.grid.y 
    @test sim1.point_types.grid.z == 
          sim2.point_types.grid.z 

In the primitives hX differs for [1].geometry.a: 0.00025f0 vs 0.00025000004f0

The grid is not the same. For these well aligned (with the axis of the grid) contacts the paint! method should not be needed actually. But of course it should still paint it properly in that case. So, there are different things to investigate.

[lmh91]

So, paining should actually get rid of these numerical issues.
I think I found the reason. A bug indeed...