briansturgill
commented
1 year ago I'll probably do more of this discussion to Manifold's board, but felt this thread needs an update. @elalish where would you want this done, Discussions?
Using union script by @platypii (translated to python and adding subtract and intersect) I managed to get a first round of timing tests comparing the C# version of the BSP algorithm with Manifold's algorithm, both using their Python bindings.
I then spent the rest of the day trying to figure out if it was actually true. I've been through it thoroughly and it appears that Manifold's booleans are 3 ORDERS OF MAGNITUDE (1000x) faster than the BSP-based booleans in JSCAD/CSharpCAD.
There are some caveats.
First, the sphere code between the two was different, but I changed the segment values (100 for JSCAD/CSharpCAD and 150 for Manifold) so that the resulting sphere had approximately the same number of vertices and faces.
The Python interface to C# is probably less efficient than the one to Manifold, however the overhead is probably not substantial realtive to the operations being tested.
The test by @platypii is edge case oriented... I don't know if that is having an effect or not.
Finally, JSCAD/CSharpCAD is faster handling the "disjoint" case as we have special handling for that. I'm assuming Manifold doesn't bother checking (it's still very fast for that case).
Here is my code for Manifold:
from pymanifold import Manifold
from time import time_ns
segments = 150
def test(x, radius, name):
s1 = Manifold.sphere(radius=1, circular_segments=segments)
s2 = Manifold.sphere(radius=radius, circular_segments=segments).translate(x, 0, 0)
start = time_ns()
ret = s1+s2
finish = time_ns()
if name == "ignore":
return
print("union", name, (finish-start)/1000000.0)
start = time_ns()
ret = s1^s2
finish = time_ns()
print("intersect", name, (finish-start)/1000000.0)
start = time_ns()
ret = s1-s2
finish = time_ns()
print("subtract", name, (finish-start)/1000000.0)
test(4, 1, "ignore");
test(4, 1, "disjoint");
test(2, 1, "touching");
test(1, 1, "overlap");
test(0, 1, "same");
test(0, 0.5, "inside");Using separate programs, I checked the output from Manifold and it appears correct. Indeed, in the case "union overlap", CSharpCAD was producing output that was not manifold. Manifold handled it correctly.
I'm hoping someone on the JSCAD team will attempt timing tests with the WASM version. I will be working on the WASM version (under C#'s new wasmtime package) soon.
hrgdavor
elalish
nmattia
z3dev
Expected Behavior
Actual Behavior
Meshlab reports 12 non manifold vertices 64 faces over non manifold edges. (I've seen this several times, here's a simple example.)
Steps to Reproduce the Problem
Run this: program output to .stl const { cylinder } = require('@jscad/modeling').primitives const { translate } = require('@jscad/modeling').transforms const { subtract, union, intersect } = require('@jscad/modeling').booleans
const main = () => { h = 8 size = 3 const inner_d = size*0.8 const outer_d = 4+size; c1 = cylinder({radius: outer_d/2, height: h}) c2 = cylinder({radius: inner_d/2, height: h}) let shape = union( subtract(c1, c2), //translate([20, 0, 0],union(c1, translate([3, 0, 0],c2))), //translate([0, 20, 0],intersect(c1, translate([3, 0, 0],c2))) ) return shape; }
module.exports = { main }
Run meshlab on the stl file.
Specifications
OpenJSCAD 2.2.21 [Linux:5.15.0-39-generic,linux:x64]