Issues when representing curved volumes

[lobis]

When representing cylinders (tubes) there is a rendering issue where a "spike" or bump appears at one end, often clipping out of the adjacent volumes.

The default number of faces is IMHO too low in order to correctly render circles, I think it should be increased. Also a simple option to increase this value globally should be available to the user. Additionally I suggest doing the same for a global transparency value which IMHO should be less than 1 by default.

How it looks like in ROOT, after exporting to GDML (note: you will have to replace "cm" by "mm" in the .gdml in order to view it like this).

How it looks like on jupyter

Jupyter Notebook code for this geometry:

@file:Repository("https://repo.kotlin.link")
@file:Repository("https://dl.bintray.com/pdvrieze/maven")
@file:DependsOn("space.kscience:visionforge-gdml-jupyter-jvm:0.2.0-dev-13")

val geometry = Gdml {
    // geometry variables
    val worldSize = 500
    // chamber
    val chamberHeight = 30 // length of the chamber
    val chamberDiameter = 102 // inner diameter of the copper chamber
    val chamberOuterSquareSide = 134 // chamber has a square footprint
    val chamberBackplateThickness = 15 // thickness of the backplate of the chamber
    // teflon disk
    val cathodeTeflonDiskHoleRadius = 15
    val cathodeTeflonDiskThickness = 5
    val cathodeCopperSupportOuterRadius = 45
    val cathodeCopperSupportInnerRadius = 8.5
    val cathodeCopperSupportThickness = 1
    // mylar cathode
    val mylarCathodeThickness = 0.004
    // patern
    val cathodePatternLineWidth = 0.3
    val cathodePatternDiskRadius = 4.25
    // readout
    val chamberTeflonWallThickness = 1
    val readoutKaptonThickness = 0.5
    val readoutCopperThickness = 0.2
    val readoutPlaneSide = 60

    structure {
        val worldMaterial = materials.composite("G4_AIR") {}
        val worldBox = solids.box("worldBox", worldSize, worldSize, worldSize) {}

        val shieldingMaterial = materials.composite("G4_Pb") {}
        val scintillatorMaterial = materials.composite("BC408") {}
        val captureMaterial = materials.composite("G4_Cd") {}

        // chamber
        val copperMaterial = materials.composite("G4_Cu") {}
        val chamberSolidBase = solids.box("chamberSolidBase", chamberOuterSquareSide, chamberOuterSquareSide, chamberHeight) {}
        val chamberSolidHole = solids.tube("chamberSolidHole", chamberDiameter / 2, chamberHeight) {}
        val chamberSolid = solids.subtraction("chamberSolid", chamberSolidBase, chamberSolidHole) {}
        val chamberBodyVolume = volume("chamberBodyVolume", copperMaterial, chamberSolid) {}
        val chamberBackplateSolid = solids.box("chamberBackplateSolid", chamberOuterSquareSide, chamberOuterSquareSide, chamberBackplateThickness)
        val chamberBackplateVolume = volume("chamberBackplateVolume", copperMaterial, chamberBackplateSolid) {}
        // chamber teflon walls
        val teflonMaterial = materials.composite("G4_TEFLON") {}
        val chamberTeflonWallSolid = solids.tube("chamberTeflonWallSolid", chamberDiameter / 2, chamberHeight) {
            rmin = chamberDiameter / 2.0 - chamberTeflonWallThickness
        }
        val chamberTeflonWallVolume = volume("chamberTeflonWallVolume", teflonMaterial, chamberTeflonWallSolid)
        // cathode
        val cathodeCopperDiskMaterial = materials.composite("G4_Cu") {}
        val cathodeWindowMaterial = materials.composite("G4_MYLAR") {}

        val cathodeTeflonDiskSolidBase = solids.tube("cathodeTeflonDiskSolidBase", chamberOuterSquareSide / 2, cathodeTeflonDiskThickness) {
            rmin = cathodeTeflonDiskHoleRadius
        }
        val cathodeCopperDiskSolid = solids.tube("cathodeCopperDiskSolid", cathodeCopperSupportOuterRadius, cathodeCopperSupportThickness) {
            rmin = cathodeCopperSupportInnerRadius
        }

        val cathodeTeflonDiskSolid = solids.subtraction("cathodeTeflonDiskSolid", cathodeTeflonDiskSolidBase, cathodeCopperDiskSolid) {}
        val cathodeTeflonDiskVolume = volume("cathodeTeflonDiskVolume", teflonMaterial, cathodeTeflonDiskSolid) {}

        val cathodeWindowSolid = solids.tube("cathodeWindowSolid", cathodeTeflonDiskHoleRadius, mylarCathodeThickness) {}
        val cathodeWindowVolume = volume("cathodeWindowVolume", cathodeWindowMaterial, cathodeWindowSolid) {}

        val cathodeFillingMaterial = materials.composite("G4_Galactic") {}
        val cathodeFillingSolidBase = solids.tube("cathodeFillingSolidBase", cathodeTeflonDiskHoleRadius, cathodeTeflonDiskThickness) {}

        val cathodeFillingSolid = solids.subtraction("cathodeFillingSolid", cathodeFillingSolidBase, cathodeCopperDiskSolid) {
            position = GdmlPosition(z = chamberHeight / 2 - mylarCathodeThickness / 2)
        }
        val cathodeFillingVolume = volume("cathodeFillingVolume", cathodeFillingMaterial, cathodeFillingSolid) {}

        // pattern
        val cathodePatternLineAux = solids.box(
                "cathodePatternLineAux",
                cathodePatternLineWidth,
                cathodeCopperSupportInnerRadius * 2,
                cathodeCopperSupportThickness
        ) {}
        val cathodePatternCentralHole = solids.tube(
                "cathodePatternCentralHole",
                cathodePatternDiskRadius - 0 * cathodePatternLineWidth,
                cathodeCopperSupportThickness * 1.1
        ) {}
        val cathodePatternLine = solids.subtraction("cathodePatternLine", cathodePatternLineAux, cathodePatternCentralHole) {}

        val cathodePatternDisk = solids.tube(
                "cathodePatternDisk",
                cathodePatternDiskRadius,
                cathodeCopperSupportThickness
        ) { rmin = cathodePatternDiskRadius - cathodePatternLineWidth }

        val cathodeCopperDiskSolidAux0 =
                solids.union("cathodeCopperDiskSolidAux0", cathodeCopperDiskSolid, cathodePatternLine) {
                    rotation = GdmlRotation(
                            "cathodePatternRotation0", x = 0, y = 0, z = 0
                    )
                }
        val cathodeCopperDiskSolidAux1 =
                solids.union("cathodeCopperDiskSolidAux1", cathodeCopperDiskSolidAux0, cathodePatternLine) {
                    rotation = GdmlRotation(
                            "cathodePatternRotation1", x = 0, y = 0, z = 45
                    )
                }
        val cathodeCopperDiskSolidAux2 =
                solids.union("cathodeCopperDiskSolidAux2", cathodeCopperDiskSolidAux1, cathodePatternLine) {
                    rotation = GdmlRotation(
                            "cathodePatternRotation2", x = 0, y = 0, z = 90
                    )
                }
        val cathodeCopperDiskSolidAux3 =
                solids.union("cathodeCopperDiskSolidAux3", cathodeCopperDiskSolidAux2, cathodePatternLine) {
                    rotation = GdmlRotation(
                            "cathodePatternRotation3", x = 0, y = 0, z = 135
                    )
                }

        val cathodeCopperDiskFinal =
                solids.union("cathodeCopperDiskFinal", cathodeCopperDiskSolidAux3, cathodePatternDisk) {}

        val cathodeCopperDiskVolume = volume("cathodeCopperDiskFinal", cathodeCopperDiskMaterial, cathodeCopperDiskFinal) {}

        val gasSolidOriginal = solids.tube(
                "gasSolidOriginal",
                chamberDiameter / 2 - chamberTeflonWallThickness,
                chamberHeight
        ) {}

        val kaptonReadoutMaterial = materials.composite("G4_KAPTON") {}
        val kaptonReadoutSolid = solids.box("kaptonReadoutSolid", chamberOuterSquareSide, chamberOuterSquareSide, readoutKaptonThickness)
        val kaptonReadoutVolume = volume("kaptonReadoutVolume", kaptonReadoutMaterial, kaptonReadoutSolid)

        val copperReadoutSolid = solids.box("copperReadoutSolid", readoutPlaneSide, readoutPlaneSide, readoutCopperThickness)
        val copperReadoutVolume = volume("copperReadoutVolume", copperMaterial, copperReadoutSolid)

        val gasSolidAux =
                solids.subtraction("gasSolidAux", gasSolidOriginal, copperReadoutSolid) {
                    position = GdmlPosition(z = -chamberHeight / 2 + readoutCopperThickness / 2)
                }

        val gasMaterial = materials.composite("G4_Ar") {}
        val gasSolid =
                solids.subtraction("gasSolid", gasSolidAux, cathodeWindowSolid) {
                    position = GdmlPosition(z = chamberHeight / 2 - mylarCathodeThickness / 2)
                    rotation = GdmlRotation(z = 45)
                }
        val gasVolume = volume("gasVolume", gasMaterial, gasSolid)

        // world setup
        world = volume("world", worldMaterial, worldBox) {
            physVolume(gasVolume) {
                name = "gas"
            }
            physVolume(kaptonReadoutVolume) {
                name = "kaptonReadout"
                position {
                    z = -chamberHeight / 2 - readoutKaptonThickness / 2
                }
            }
            physVolume(copperReadoutVolume) {
                name = "copperReadout"
                position {
                    z = -chamberHeight / 2 + readoutCopperThickness / 2
                }
                rotation { z = 45 }
            }
            physVolume(chamberBodyVolume) {
                name = "chamberBody"
            }
            physVolume(chamberBackplateVolume) {
                name = "chamberBackplate"
                position {
                    z = -chamberHeight / 2 - readoutKaptonThickness - chamberBackplateThickness / 2
                }
            }
            physVolume(chamberTeflonWallVolume) {
                name = "chamberTeflonWall"
            }
            physVolume(cathodeTeflonDiskVolume) {
                name = "cathodeTeflonDisk"
                position {
                    z = chamberHeight / 2 + cathodeTeflonDiskThickness / 2
                }
            }
            physVolume(cathodeCopperDiskVolume) {
                name = "cathodeCopperDisk"
                position {
                    z = chamberHeight / 2 + cathodeCopperSupportThickness / 2
                }
            }
            physVolume(cathodeWindowVolume) {
                name = "cathodeWindow"
                position {
                    z = chamberHeight / 2 - mylarCathodeThickness / 2
                }
            }
            physVolume(cathodeFillingVolume) {
                name = "cathodeFilling"
                position {
                    z = chamberHeight / 2 + cathodeTeflonDiskThickness / 2
                }
            }
        }
    }
}

[altavir]

The problem with transparency and increased detail is that it greatly impacts the performance on complex scene-graphs. But I agree that it should be an option. There are also two actual places, where one can increase the detail: during gdml to VF conversion and during the rendering. I think we can tweak both.

[altavir]

I've increased the default level for spheres and cones and now it looks much better: It still could be adjusted in the converter (need to add some configuration options for that).