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Merge pull request #177 from adrianVmariano/master

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Update vnf_volume and vnf_centroid to avoid vnf_triangulate.  Huge speed gain.
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Revar Desmera 2020-06-13 15:05:30 -07:00 committed by GitHub
commit 1da733fd32
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1 changed files with 20 additions and 17 deletions
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37
vnf.scad
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@ -356,16 +356,18 @@ module vnf_polyhedron(vnf, convexity=2) {
// Description:
// Returns the volume enclosed by the given manifold VNF. The VNF must describe a valid polyhedron with consistent face direction and
// no holes; otherwise the results are undefined. Returns a positive volume if face direction is clockwise and a negative volume
// if face direction is counter-clockwise.
// if face direction is counter-clockwise.
function vnf_volume(vnf) =
let(
vnf = vnf_triangulate(vnf),
verts = vnf[0]
) sum([
for(face_index=vnf[1]) let(
face = select(verts, face_index),
n = cross(face[2]-face[0],face[1]-face[0])
) face[0] * n
let(verts = vnf[0])
sum([
for(face=vnf[1], j=[1:1:len(face)-2])
let(
v0 = verts[face[0]],
v1 = verts[face[j]],
v2 = verts[face[j+1]],
n = cross(v2-v0,v1-v0)
)
v0 * n
])/6;
@ -379,19 +381,20 @@ function vnf_volume(vnf) =
// Algorithm from: https://wwwf.imperial.ac.uk/~rn/centroid.pdf
function vnf_centroid(vnf) =
let(
vnf = vnf_triangulate(vnf),
verts = vnf[0],
val=sum([
for(face_index=vnf[1])
for(face=vnf[1], j=[1:1:len(face)-2])
let(
face = select(verts, face_index),
n = cross(face[2]-face[0],face[1]-face[0])
v0 = verts[face[0]],
v1 = verts[face[j]],
v2 = verts[face[j+1]],
n = cross(v2-v0,v1-v0)
) [
face[0] * n,
v0 * n,
vmul(n,
sqr(face[0] + face[1]) +
sqr(face[0] + face[2]) +
sqr(face[1] + face[2])
sqr(v0 + v1) +
sqr(v0 + v2) +
sqr(v1 + v2)
)
]
])