V2 : odd result of measureArea()

[minatani]

Expected Behavior

An object with area, bounds and volume is located at the position pointed by translate().

Actual Behavior

In some case, an object's area is disappeared by translate() with certain values.

Steps to Reproduce the Problem

The problem can be reproduced by this script.

// V2

const { cuboid, cylinder } = require('@jscad/modeling').primitives
const { translateX, translateY } = require('@jscad/modeling').transforms
const { subtract } = require('@jscad/modeling').booleans
const { measureArea, measureBounds, measureVolume } = require('@jscad/modeling').measurements

const main = () => {
const plateZ=1;
const len=100;
const holeRad=3;
const holeDis=9.5;
let ret;
let binder=translateX([len/2],
cuboid({size: [len, holeDis, plateZ]}));
for (i=holeDis/2; i <=len-holeDis/2; i+=holeDis ) { // punching loose-leaf notebook's holes
binder=subtract(binder, translateX([i],
cylinder({ startRadius: holeRad, endRadius: holeRad, height: plateZ })));
}
for (y=0; y<=3; y+=0.1) {
ret=translateY([y], binder);
console.log(y pos: ${y}, Area: ${measureArea(ret)}, Bounds: ${measureBounds(ret)}, Volume: ${measureVolume(ret)}\n)
}
return [ ret ]
}

module.exports = { main }

Specifications

• Version: V2 1b159c0
• Platform: Debian Stretch, nodejs v9.15.2
• Environment: cli

[z3dev]

Please change translateX([len/2], ...) to translateX(len/2, ...)

These functions are...

translateX( NUMBER, ...objects )
translateY( NUMBER, ...objects )

Hope that helps.

[minatani]

Thank you for your kind reply.
But, the result is same even if parameters of translateX()/translateY() are corrected.

JSCAD: generating output

from: binder-test.js
to: ../stl/binder-test.stl �[33m(STereoLithography, Binary)

y pos: 0, Area: 1767.8944694294753, Bounds: 0,-4.75,-0.5,100,4.75,0.5, Volume: 681.3996182477186

y pos: 0.1, Area: 1773.7473318485027, Bounds: 0,-4.650000095367432,-0.5,100,4.849999904632568,0.5, Volume: 681.3996225578863

y pos: 0.2, Area: 1773.7473317320587, Bounds: 0,-4.550000190734863,-0.5,100,4.949999809265137,0.5, Volume: 681.3996186298648

y pos: 0.30000000000000004, Area: NaN, Bounds: 0,-4.449999809265137,-0.5,100,5.050000190734863,0.5, Volume: 681.3996235487045

y pos: 0.4, Area: 1767.8944691418465, Bounds: 0,-4.349999904632568,-0.5,100,5.150000095367432,0.5, Volume: 681.3996183980468

y pos: 0.5, Area: 1767.8944678037044, Bounds: 0,-4.25,-0.5,100,5.25,0.5, Volume: 681.3996190990447

y pos: 0.6, Area: NaN, Bounds: 0,-4.150000095367432,-0.5,100,5.349999904632568,0.5, Volume: 681.399616254163

y pos: 0.7, Area: NaN, Bounds: 0,-4.050000190734863,-0.5,100,5.449999809265137,0.5, Volume: 681.3996229324766

y pos: 0.7999999999999999, Area: NaN, Bounds: 0,-3.950000047683716,-0.5,100,5.550000190734863,0.5, Volume: 681.3996392061447

y pos: 0.8999999999999999, Area: NaN, Bounds: 0,-3.8499999046325684,-0.5,100,5.650000095367432,0.5, Volume: 681.3996208583865

y pos: 0.9999999999999999, Area: 1773.7472879814206, Bounds: 0,-3.75,-0.5,100,5.75,0.5, Volume: 681.3996177179633

y pos: 1.0999999999999999, Area: NaN, Bounds: 0,-3.6500000953674316,-0.5,100,5.849999904632568,0.5, Volume: 681.3996214888167

y pos: 1.2, Area: NaN, Bounds: 0,-3.549999952316284,-0.5,100,5.949999809265137,0.5, Volume: 681.3996094907109

y pos: 1.3, Area: NaN, Bounds: 0,-3.450000047683716,-0.5,100,6.050000190734863,0.5, Volume: 681.3996318118301

y pos: 1.4000000000000001, Area: NaN, Bounds: 0,-3.3499999046325684,-0.5,100,6.150000095367432,0.5, Volume: 681.3996180532441

y pos: 1.5000000000000002, Area: 1767.8944321269767, Bounds: 0,-3.25,-0.5,100,6.25,0.5, Volume: 681.3996236057928

y pos: 1.6000000000000003, Area: NaN, Bounds: 0,-3.1500000953674316,-0.5,100,6.349999904632568,0.5, Volume: 681.3996211386387

y pos: 1.7000000000000004, Area: NaN, Bounds: 0,-3.049999952316284,-0.5,100,6.449999809265137,0.5, Volume: 681.3996082361081

y pos: 1.8000000000000005, Area: NaN, Bounds: 0,-2.950000047683716,-0.5,100,6.550000190734863,0.5, Volume: 681.3996309595591

y pos: 1.9000000000000006, Area: NaN, Bounds: 0,-2.8499999046325684,-0.5,100,6.650000095367432,0.5, Volume: 681.399621775875

y pos: 2.0000000000000004, Area: 1767.8944321988454, Bounds: 0,-2.75,-0.5,100,6.75,0.5, Volume: 681.3996209918657

y pos: 2.1000000000000005, Area: NaN, Bounds: 0,-2.6500000953674316,-0.5,100,6.849999904632568,0.5, Volume: 681.3996138859183

y pos: 2.2000000000000006, Area: NaN, Bounds: 0,-2.549999952316284,-0.5,100,6.949999809265137,0.5, Volume: 681.3996091818095

y pos: 2.3000000000000007, Area: NaN, Bounds: 0,-2.450000047683716,-0.5,100,7.050000190734863,0.5, Volume: 681.3996348221616

y pos: 2.400000000000001, Area: NaN, Bounds: 0,-2.3499999046325684,-0.5,100,7.150000095367432,0.5, Volume: 681.3996062258217

y pos: 2.500000000000001, Area: NaN, Bounds: 0,-2.25,-0.5,100,7.25,0.5, Volume: 681.3996218566804

y pos: 2.600000000000001, Area: NaN, Bounds: 0,-2.1500000953674316,-0.5,100,7.349999904632568,0.5, Volume: 681.3996136115277

y pos: 2.700000000000001, Area: 1761.962705186312, Bounds: 0,-2.049999952316284,-0.5,100,7.449999809265137,0.5, Volume: 681.3996092097775

y pos: 2.800000000000001, Area: NaN, Bounds: 0,-1.9500000476837158,-0.5,100,7.550000190734863,0.5, Volume: 681.3996317419461

y pos: 2.9000000000000012, Area: NaN, Bounds: 0,-1.8499999046325684,-0.5,100,7.650000095367432,0.5, Volume: 681.3996105219315

[z3dev]

@minatani thanks again. there's an issue with the calculation of area, i.e. measureArea()

It seems to be related to the Float32Array values, as the results are inconsistent, even after a small fix.

y: 0, a: 1767.8944694294753, v: 681.3996182477186
y: 0.1, a: 1773.7473318485027, v: 681.3996225578863
y: 0.2, a: 1773.7473317320587, v: 681.3996186298648
y: 0.30000000000000004, a: 1764.928558634499, v: 681.3996235487045
y: 0.4, a: 1767.8944691418465, v: 681.3996183980468
y: 0.5, a: 1767.8944678037044, v: 681.3996190990447
y: 0.6, a: 1773.7473170853725, v: 681.399616254163
y: 0.7, a: 1773.7473157766622, v: 681.3996229324766
y: 0.7999999999999999, a: 1770.7815040039052, v: 681.3996392061447
y: 0.8999999999999999, a: 1767.8944090107973, v: 681.3996208583865
y: 0.9999999999999999, a: 1773.7472879814206, v: 681.3996177179633
y: 1.0999999999999999, a: 1767.8944582307183, v: 681.3996214888167
y: 1.2, a: 1764.928554816633, v: 681.3996094907109
y: 1.3, a: 1764.928639300917, v: 681.3996318118301
y: 1.4000000000000001, a: 1762.041544237735, v: 681.3996180532441
y: 1.5000000000000002, a: 1767.8944321269767, v: 681.3996236057928
y: 1.6000000000000003, a: 1767.8944582307183, v: 681.3996211386387
y: 1.7000000000000004, a: 1764.9285547687196, v: 681.3996082361081
y: 1.8000000000000005, a: 1764.9286392530034, v: 681.3996309595591
y: 1.9000000000000006, a: 1762.0415441179528, v: 681.399621775875
y: 2.0000000000000004, a: 1767.8944321988454, v: 681.3996209918657
y: 2.1000000000000005, a: 1773.7472686816834, v: 681.3996138859183
y: 2.2000000000000006, a: 1770.7814051998012, v: 681.3996091818095
y: 2.3000000000000007, a: 1770.7814896840846, v: 681.3996348221616
y: 2.400000000000001, a: 1773.7472686816834, v: 681.3996062258217
y: 2.500000000000001, a: 1773.747252243277, v: 681.3996218566804
y: 2.600000000000001, a: 1767.8944141317932, v: 681.3996136115277
y: 2.700000000000001, a: 1761.962705186312, v: 681.3996092097775
y: 2.800000000000001, a: 1767.8155274878256, v: 681.3996317419461
y: 2.9000000000000012, a: 1767.8944141317932, v: 681.3996105219315

If I switch to Number values then the results are consistent.

y: 0, a: 1765.3497124738026, v: 680.0000000000005
y: 0.1, a: 1765.3497124738026, v: 680.0000000000002
y: 0.2, a: 1765.3497124738026, v: 680.0000000000005
y: 0.30000000000000004, a: 1765.3497124738028, v: 680.0000000000001
y: 0.4, a: 1765.3497124738028, v: 680.0000000000003
y: 0.5, a: 1765.3497124738028, v: 680.0000000000002
y: 0.6, a: 1765.3497124738026, v: 680.0000000000003
y: 0.7, a: 1765.3497124738026, v: 680.0000000000007
y: 0.7999999999999999, a: 1765.3497124738028, v: 680.0000000000002
y: 0.8999999999999999, a: 1765.3497124738026, v: 680.0000000000005
y: 0.9999999999999999, a: 1765.3497124738026, v: 680.0000000000007
y: 1.0999999999999999, a: 1765.3497124738028, v: 680.0000000000005
y: 1.2, a: 1765.3497124738026, v: 680.0000000000003
y: 1.3, a: 1765.3497124738028, v: 680.0000000000007
y: 1.4000000000000001, a: 1765.3497124738026, v: 680.0000000000003
y: 1.5000000000000002, a: 1765.3497124738028, v: 680.0000000000002
y: 1.6000000000000003, a: 1765.3497124738026, v: 680.0000000000005
y: 1.7000000000000004, a: 1765.3497124738028, v: 680.0000000000005
y: 1.8000000000000005, a: 1765.3497124738026, v: 680.0000000000007
y: 1.9000000000000006, a: 1765.3497124738028, v: 680.0000000000006
y: 2.0000000000000004, a: 1765.3497124738026, v: 680.0000000000006
y: 2.1000000000000005, a: 1765.3497124738028, v: 680.0000000000005
y: 2.2000000000000006, a: 1765.3497124738026, v: 680.0000000000006
y: 2.3000000000000007, a: 1765.3497124738028, v: 680.0000000000006
y: 2.400000000000001, a: 1765.3497124738026, v: 680.0000000000005
y: 2.500000000000001, a: 1765.3497124738028, v: 680.0000000000005
y: 2.600000000000001, a: 1765.3497124738026, v: 680.0000000000006
y: 2.700000000000001, a: 1765.3497124738028, v: 680.0000000000007
y: 2.800000000000001, a: 1765.3497124738028, v: 680.0000000000003
y: 2.9000000000000012, a: 1765.3497124738028, v: 680.0000000000002

[z3dev]

UG. The number of polygons is totally different as well.

Float32Array : 362 polygons
Number: 260 polygons

This is going to take some time... UG

[z3dev]

I looked into this further.

This is an issue with the reTesselateCoplanarPolygons() function. This function is merging/adding polygons to the geometry, and obviously has MAJOR issues if using Float32Array.

[z3dev]

Good news. I wrote a new function called mergeCoplanarPolygons() to replace reTesselateCoplanarPolygons(). After making the switch...

y: 0, a: 1758.2897793046259, v: 680.0000281924738
y: 0.1, a: 1758.2897778645586, v: 680.0000279028617
y: 0.2, a: 1758.2897698433073, v: 680.0000179016224
y: 0.30000000000000004, a: 1758.2897917867758, v: 680.0000325041563
y: 0.4, a: 1758.289780108269, v: 680.0000341569478
y: 0.5, a: 1758.2897794829437, v: 680.0000282458033
y: 0.6, a: 1758.289779676747, v: 680.0000167293766
y: 0.7, a: 1758.2897631585029, v: 680.0000241641173
y: 0.7999999999999999, a: 1758.289826408774, v: 680.0000509627844
y: 0.8999999999999999, a: 1758.289775983483, v: 680.0000322173146
y: 0.9999999999999999, a: 1758.2897782801392, v: 680.0000302566373
y: 1.0999999999999999, a: 1758.2897813435984, v: 680.0000276050015
y: 1.2, a: 1758.2897375326584, v: 680.0000088949258
y: 1.3, a: 1758.2898231921508, v: 680.0000484535009
y: 1.4000000000000001, a: 1758.289777590321, v: 680.0000323807484
y: 1.5000000000000002, a: 1758.2897762585026, v: 680.0000306774015
y: 1.6000000000000003, a: 1758.28977883004, v: 680.0000286949361
y: 1.7000000000000004, a: 1758.289732551647, v: 680.0000181414407
y: 1.8000000000000005, a: 1758.289827584198, v: 680.0000482774943
y: 1.9000000000000006, a: 1758.2897801689155, v: 680.0000270477339
y: 2.0000000000000004, a: 1758.2897759259397, v: 680.0000272686548
y: 2.1000000000000005, a: 1758.2897798055894, v: 680.0000218140627
y: 2.2000000000000006, a: 1758.2897329040527, v: 680.0000075045967
y: 2.3000000000000007, a: 1758.2898279366038, v: 680.0000502504489
y: 2.400000000000001, a: 1758.2897797964886, v: 680.0000241298765
y: 2.500000000000001, a: 1758.289777767429, v: 680.0000256866264
y: 2.600000000000001, a: 1758.2897783225858, v: 680.0000277191657
y: 2.700000000000001, a: 1758.2897321279813, v: 680.0000109852845
y: 2.800000000000001, a: 1758.2898284630703, v: 680.0000473587893
y: 2.9000000000000012, a: 1758.289779056813, v: 680.0000202794564

And there are now 470 polygons.

FYI, the subtract will produce 498 polygons without some kind of merge/retesselation.

[minatani]

Thank you for your immediate investigation and fix.
I'm looking forward to commit this improvement.

[z3dev]

@minatani The calculation of volumes should be consistent now. Please try the latest version of V2 branch.

If resolved then close this issue.

[minatani]

Confirmed.