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Show volume of current group alongside total volume.

pull/487/head
EvilSpirit 2019-09-11 10:28:15 +00:00 committed by whitequark
parent a0e992374d
commit 915f55aabc
4 changed files with 74 additions and 57 deletions
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2
CHANGELOG.md
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@ -70,6 +70,8 @@ New measurement/analysis features:
* New command for measuring center of mass, with live updates as the sketch
changes, "Analyze → Center of Mass".
* New option for displaying areas of closed contours.
* When calculating volume of the mesh, volume of the solid from the current
group is now shown alongside total volume of all solids.
* When selecting a point and a line, projected distance to current
workplane is displayed.

53
src/mesh.cpp
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@ -1128,3 +1128,56 @@ void SMesh::RemoveDegenerateTriangles() {
}
l.RemoveTagged();
}
double SMesh::CalculateVolume() const {
double vol = 0;
for(STriangle tr : l) {
// Translate to place vertex A at (x, y, 0)
Vector trans = Vector::From(tr.a.x, tr.a.y, 0);
tr.a = (tr.a).Minus(trans);
tr.b = (tr.b).Minus(trans);
tr.c = (tr.c).Minus(trans);
// Rotate to place vertex B on the y-axis. Depending on
// whether the triangle is CW or CCW, C is either to the
// right or to the left of the y-axis. This handles the
// sign of our normal.
Vector u = Vector::From(-tr.b.y, tr.b.x, 0);
u = u.WithMagnitude(1);
Vector v = Vector::From(tr.b.x, tr.b.y, 0);
v = v.WithMagnitude(1);
Vector n = Vector::From(0, 0, 1);
tr.a = (tr.a).DotInToCsys(u, v, n);
tr.b = (tr.b).DotInToCsys(u, v, n);
tr.c = (tr.c).DotInToCsys(u, v, n);
n = tr.Normal().WithMagnitude(1);
// Triangles on edge don't contribute
if(fabs(n.z) < LENGTH_EPS) continue;
// The plane has equation p dot n = a dot n
double d = (tr.a).Dot(n);
// nx*x + ny*y + nz*z = d
// nz*z = d - nx*x - ny*y
double A = -n.x/n.z, B = -n.y/n.z, C = d/n.z;
double mac = tr.c.y/tr.c.x, mbc = (tr.c.y - tr.b.y)/tr.c.x;
double xc = tr.c.x, yb = tr.b.y;
// I asked Maple for
// int(int(A*x + B*y +C, y=mac*x..(mbc*x + yb)), x=0..xc);
double integral =
(1.0/3)*(
A*(mbc-mac)+
(1.0/2)*B*(mbc*mbc-mac*mac)
)*(xc*xc*xc)+
(1.0/2)*(A*yb+B*yb*mbc+C*(mbc-mac))*xc*xc+
C*yb*xc+
(1.0/2)*B*yb*yb*xc;
vol += integral;
}
return vol;
}

1
src/polygon.h
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@ -280,6 +280,7 @@ public:
void PrecomputeTransparency();
void RemoveDegenerateTriangles();
double CalculateVolume() const;
bool IsEmpty() const;
void RemapFaces(Group *g, int remap);

75
src/solvespace.cpp
View File

@ -772,65 +772,26 @@ void SolveSpaceUI::MenuAnalyze(Command id) {
}
case Command::VOLUME: {
SMesh *m = &(SK.GetGroup(SS.GW.activeGroup)->displayMesh);
Group *g = SK.GetGroup(SS.GW.activeGroup);
double totalVol = g->displayMesh.CalculateVolume();
std::string msg = ssprintf(
_("The volume of the solid model is:\n\n"
" %s"),
SS.MmToStringSI(totalVol, /*dim=*/3).c_str());
double vol = 0;
int i;
for(i = 0; i < m->l.n; i++) {
STriangle tr = m->l[i];
// Translate to place vertex A at (x, y, 0)
Vector trans = Vector::From(tr.a.x, tr.a.y, 0);
tr.a = (tr.a).Minus(trans);
tr.b = (tr.b).Minus(trans);
tr.c = (tr.c).Minus(trans);
// Rotate to place vertex B on the y-axis. Depending on
// whether the triangle is CW or CCW, C is either to the
// right or to the left of the y-axis. This handles the
// sign of our normal.
Vector u = Vector::From(-tr.b.y, tr.b.x, 0);
u = u.WithMagnitude(1);
Vector v = Vector::From(tr.b.x, tr.b.y, 0);
v = v.WithMagnitude(1);
Vector n = Vector::From(0, 0, 1);
tr.a = (tr.a).DotInToCsys(u, v, n);
tr.b = (tr.b).DotInToCsys(u, v, n);
tr.c = (tr.c).DotInToCsys(u, v, n);
n = tr.Normal().WithMagnitude(1);
// Triangles on edge don't contribute
if(fabs(n.z) < LENGTH_EPS) continue;
// The plane has equation p dot n = a dot n
double d = (tr.a).Dot(n);
// nx*x + ny*y + nz*z = d
// nz*z = d - nx*x - ny*y
double A = -n.x/n.z, B = -n.y/n.z, C = d/n.z;
double mac = tr.c.y/tr.c.x, mbc = (tr.c.y - tr.b.y)/tr.c.x;
double xc = tr.c.x, yb = tr.b.y;
// I asked Maple for
// int(int(A*x + B*y +C, y=mac*x..(mbc*x + yb)), x=0..xc);
double integral =
(1.0/3)*(
A*(mbc-mac)+
(1.0/2)*B*(mbc*mbc-mac*mac)
)*(xc*xc*xc)+
(1.0/2)*(A*yb+B*yb*mbc+C*(mbc-mac))*xc*xc+
C*yb*xc+
(1.0/2)*B*yb*yb*xc;
vol += integral;
SMesh curMesh = {};
g->thisShell.TriangulateInto(&curMesh);
double curVol = curMesh.CalculateVolume();
if(curVol > 0.0) {
msg += ssprintf(
_("\nThe volume of current group mesh is:\n\n"
" %s"),
SS.MmToStringSI(curVol, /*dim=*/3).c_str());
}
Message(_("The volume of the solid model is:\n\n"
" %s\n\n"
"Curved surfaces have been approximated as triangles.\n"
"This introduces error, typically of around 1%%."),
SS.MmToStringSI(vol, /*dim=*/3).c_str());
msg += _("\n\nCurved surfaces have been approximated as triangles.\n"
"This introduces error, typically of around 1%.");
Message("%s", msg.c_str());
break;
}