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Several smoothing fixes #844

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merged 2 commits into from
Jun 13, 2024
Merged

Several smoothing fixes #844

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980b830
fixed several bugs
elalish Jun 13, 2024
10d84fe
fixed average rotation
elalish Jun 13, 2024
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69 changes: 46 additions & 23 deletions src/manifold/src/smoothing.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,16 +21,27 @@
namespace {
using namespace manifold;

glm::vec3 OrthogonalTo(glm::vec3 in, glm::vec3 ref) {
in -= glm::dot(in, ref) * ref;
return in;
// Returns a normalized vector orthogonal to ref, in the plane of ref and in,
// unless in and ref are colinear, in which case it falls back to the plane of
// ref and altIn.
glm::vec3 OrthogonalTo(glm::vec3 in, glm::vec3 altIn, glm::vec3 ref) {
glm::vec3 out = in - glm::dot(in, ref) * ref;
if (glm::dot(out, out) < kTolerance * glm::dot(in, in)) {
out = altIn - glm::dot(altIn, ref) * ref;
}
return SafeNormalize(out);
}

float Wrap(float radians) {
return radians < -glm::pi<float>() ? radians + glm::two_pi<float>()
: radians > glm::pi<float>() ? radians - glm::two_pi<float>()
: radians;
}

// Get the angle between two unit-vectors.
float AngleBetween(glm::vec3 a, glm::vec3 b) {
const float dot = glm::dot(a, b);
return dot >= 1 ? kTolerance
: (dot <= -1 ? glm::pi<float>() : glm::acos(dot));
return dot >= 1 ? 0 : (dot <= -1 ? glm::pi<float>() : glm::acos(dot));
}

// Calculate a tangent vector in the form of a weighted cubic Bezier taking as
Expand Down Expand Up @@ -146,12 +157,10 @@ struct InterpTri {
const glm::mat2x3 nTangentsX(SafeNormalize(glm::vec3(tangentsX[0])),
-SafeNormalize(glm::vec3(tangentsX[1])));
const glm::mat2x3 biTangents = {
SafeNormalize(OrthogonalTo(
glm::vec3(tangentsY[0]) + kTolerance * (anchor - corners[0]),
nTangentsX[0])),
SafeNormalize(OrthogonalTo(
glm::vec3(tangentsY[1]) + kTolerance * (anchor - corners[1]),
nTangentsX[1]))};
OrthogonalTo(glm::vec3(tangentsY[0]), (anchor - corners[0]),
nTangentsX[0]),
OrthogonalTo(glm::vec3(tangentsY[1]), (anchor - corners[1]),
nTangentsX[1])};

const glm::quat q0 =
glm::quat_cast(glm::mat3(nTangentsX[0], biTangents[0],
Expand Down Expand Up @@ -580,8 +589,8 @@ void Manifold::Impl::SetNormals(int normalIdx, float minSharpAngle) {
// more constant curvature to meet the opposite normal. Achieve
// this by pointing the tangent toward the opposite bezier
// control point instead of the vert itself.
pos += glm::vec3(
CircularTangent(OrthogonalTo(edgeVec, normal), edgeVec));
pos += glm::vec3(TangentFromNormal(
normal, halfedge_[current].pairedHalfedge));
}
return FaceEdge(
{halfedge_[current].face, SafeNormalize(pos - centerPos)});
Expand Down Expand Up @@ -720,8 +729,9 @@ void Manifold::Impl::DistributeTangents(const Vec<bool>& fixedHalfedges) {
const glm::vec3 center = vertPos_[halfedge_[halfedge].startVert];
glm::vec3 lastEdgeVec =
SafeNormalize(vertPos_[halfedge_[halfedge].endVert] - center);
glm::vec3 lastTangent =
const glm::vec3 firstTangent =
SafeNormalize(glm::vec3(halfedgeTangent_[halfedge]));
glm::vec3 lastTangent = firstTangent;
int current = halfedge;
do {
current = NextHalfedge(halfedge_[current].pairedHalfedge);
Expand All @@ -730,16 +740,20 @@ void Manifold::Impl::DistributeTangents(const Vec<bool>& fixedHalfedges) {
SafeNormalize(vertPos_[halfedge_[current].endVert] - center);
const glm::vec3 thisTangent =
SafeNormalize(glm::vec3(halfedgeTangent_[current]));
const glm::vec3 cp = glm::cross(thisTangent, lastTangent);
normal += cp;
normal += glm::cross(thisTangent, lastTangent);
// cumulative sum
desiredAngle.push_back(
AngleBetween(thisEdgeVec, lastEdgeVec) +
(desiredAngle.size() > 0 ? desiredAngle.back() : 0));
currentAngle.push_back(
AngleBetween(thisTangent, lastTangent) *
glm::sign(glm::dot(cp, approxNormal)) +
(currentAngle.size() > 0 ? currentAngle.back() : 0));
if (current == halfedge) {
currentAngle.push_back(glm::two_pi<float>());
} else {
currentAngle.push_back(AngleBetween(thisTangent, firstTangent));
if (glm::dot(approxNormal, glm::cross(thisTangent, firstTangent)) <
0) {
currentAngle.back() = glm::two_pi<float>() - currentAngle.back();
}
}
lastEdgeVec = thisEdgeVec;
lastTangent = thisTangent;
} while (!fixedHalfedges[current]);
Expand All @@ -750,7 +764,7 @@ void Manifold::Impl::DistributeTangents(const Vec<bool>& fixedHalfedges) {
float offset = 0;
if (current == halfedge) { // only one - find average offset
for (int i = 0; i < currentAngle.size(); ++i) {
offset += currentAngle[i] - scale * desiredAngle[i];
offset += Wrap(currentAngle[i] - scale * desiredAngle[i]);
}
offset /= currentAngle.size();
}
Expand All @@ -760,8 +774,17 @@ void Manifold::Impl::DistributeTangents(const Vec<bool>& fixedHalfedges) {
do {
current = NextHalfedge(halfedge_[current].pairedHalfedge);
if (IsMarkedInsideQuad(current)) continue;
const float angle =
currentAngle[i] - scale * desiredAngle[i] - offset;
desiredAngle[i] *= scale;
const float lastAngle = i > 0 ? desiredAngle[i - 1] : 0;
// shrink obtuse angles
if (desiredAngle[i] - lastAngle > glm::pi<float>()) {
desiredAngle[i] = lastAngle + glm::pi<float>();
} else if (i + 1 < desiredAngle.size() &&
scale * desiredAngle[i + 1] - desiredAngle[i] >
glm::pi<float>()) {
desiredAngle[i] = scale * desiredAngle[i + 1] - glm::pi<float>();
}
const float angle = currentAngle[i] - desiredAngle[i] - offset;
glm::vec3 tangent(halfedgeTangent_[current]);
halfedgeTangent_[current] = glm::vec4(
glm::rotate(tangent, angle, normal), halfedgeTangent_[current].w);
Expand Down
12 changes: 6 additions & 6 deletions test/smooth_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -339,8 +339,8 @@ TEST(Smooth, SineSurface) {
Manifold smoothed =
Manifold(surface).CalculateNormals(0, 50).SmoothByNormals(0).Refine(8);
auto prop = smoothed.GetProperties();
EXPECT_NEAR(prop.volume, 8.07, 0.01);
EXPECT_NEAR(prop.surfaceArea, 30.88, 0.01);
EXPECT_NEAR(prop.volume, 8.09, 0.01);
EXPECT_NEAR(prop.surfaceArea, 30.93, 0.01);
EXPECT_EQ(smoothed.Genus(), 0);

Manifold smoothed1 = Manifold(surface).SmoothOut(50).Refine(8);
Expand All @@ -351,14 +351,14 @@ TEST(Smooth, SineSurface) {

Manifold smoothed2 = Manifold(surface).SmoothOut(180, 1).Refine(8);
auto prop2 = smoothed2.GetProperties();
EXPECT_NEAR(prop2.volume, 9.02, 0.01);
EXPECT_NEAR(prop2.surfaceArea, 33.56, 0.01);
EXPECT_NEAR(prop2.volume, 9.00, 0.01);
EXPECT_NEAR(prop2.surfaceArea, 33.61, 0.01);
EXPECT_EQ(smoothed2.Genus(), 0);

Manifold smoothed3 = Manifold(surface).SmoothOut(50, 0.5).Refine(8);
auto prop3 = smoothed3.GetProperties();
EXPECT_NEAR(prop3.volume, 8.46, 0.01);
EXPECT_NEAR(prop3.surfaceArea, 31.66, 0.01);
EXPECT_NEAR(prop3.volume, 8.43, 0.01);
EXPECT_NEAR(prop3.surfaceArea, 31.72, 0.01);
EXPECT_EQ(smoothed3.Genus(), 0);

#ifdef MANIFOLD_EXPORT
Expand Down
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