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Fixing bugs in tensor patch shading

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This commit is contained in:
Jakub Melka 2019-09-21 15:16:37 +02:00
parent 252203d6b9
commit d5d92a4e54
2 changed files with 83 additions and 79 deletions
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159
PdfForQtLib/sources/pdfpattern.cpp
View File

@ -1696,9 +1696,9 @@ QPointF PDFTensorPatch::getValue(PDFReal u, PDFReal v, int derivativeOrderU, int
{
QPointF result(0.0, 0.0);
for (int i = 0; i < 3; ++i)
for (int i = 0; i < 4; ++i)
{
for (int j = 0; j < 3; ++j)
for (int j = 0; j < 4; ++j)
{
result += m_P[i][j] * B(i, u, derivativeOrderU) * B(j, v, derivativeOrderV);
}
@ -2079,9 +2079,48 @@ PDFMesh PDFTensorProductPatchShading::createMesh(const PDFMeshQualitySettings& s
return mesh;
}
void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
const PDFMeshQualitySettings& settings,
const PDFTensorPatch& patch) const
struct PDFTensorProductPatchShadingBase::Triangle
{
std::array<QPointF, 3> uvCoordinates;
std::array<QPointF, 3> devicePoints;
QPointF getCenter() const
{
constexpr PDFReal coefficient = 1.0 / 3.0;
return (uvCoordinates[0] + uvCoordinates[1] + uvCoordinates[2]) * coefficient;
}
PDFReal getCurvature(const PDFTensorPatch& patch) const
{
QPointF uv = getCenter();
return patch.getCurvature_u(uv.x(), uv.y()) + patch.getCurvature_v(uv.x(), uv.y());
}
void fillTriangleDevicePoints(const PDFTensorPatch& patch)
{
Q_ASSERT(uvCoordinates.size() == devicePoints.size());
for (size_t i = 0; i < uvCoordinates.size(); ++i)
{
devicePoints[i] = patch.getValue(uvCoordinates[i].x(), uvCoordinates[i].y());
}
}
PDFReal getArea() const
{
const PDFReal x1 = devicePoints[0].x();
const PDFReal y1 = devicePoints[0].y();
const PDFReal x2 = devicePoints[1].x();
const PDFReal y2 = devicePoints[1].y();
const PDFReal x3 = devicePoints[2].x();
const PDFReal y3 = devicePoints[2].y();
// Use shoelace formula to determine the triangle area, see
// https://en.wikipedia.org/wiki/Shoelace_formula
return std::fabs(0.5 * (x1 * y2 + x2 * y3 + x3 * y1 - x2 * y1 - x3 * y2 - x1 * y3));
}
};
void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh, const PDFMeshQualitySettings& settings, const PDFTensorPatch& patch) const
{
// We implement algorithm similar to Ruppert's algorithm (see https://en.wikipedia.org/wiki/Ruppert%27s_algorithm), but
// we do not need a mesh for FEM calculation, so we do not care about quality of the triangles (we can have triangles with
@ -2118,33 +2157,6 @@ void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
};
std::for_each(std::execution::parallel_policy(), range.begin(), range.end(), updateCurvature);
struct Triangle
{
std::array<QPointF, 3> uvCoordinates;
std::array<QPointF, 3> devicePoints;
QPointF getCenter() const
{
constexpr PDFReal coefficient = 1.0 / 3.0;
return (uvCoordinates[0] + uvCoordinates[1] + uvCoordinates[2]) * coefficient;
}
PDFReal getCurvature(const PDFTensorPatch& patch) const
{
QPointF uv = getCenter();
return patch.getCurvature_u(uv.x(), uv.y()) + patch.getCurvature_v(uv.x(), uv.y());
}
void fillTriangleDevicePoints(const PDFTensorPatch& patch)
{
Q_ASSERT(uvCoordinates.size() == devicePoints.size());
for (size_t i = 0; i < uvCoordinates.size(); ++i)
{
devicePoints[i] = patch.getValue(uvCoordinates[i].x(), uvCoordinates[i].y());
}
}
};
auto getColorForUV = [&](PDFReal u, PDFReal v)
{
// Perform bilinear interpolation of colors, u is column, v is row
@ -2172,14 +2184,6 @@ void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
std::vector<Triangle> unfinishedTriangles = { workStartA, workStartB };
std::vector<Triangle> finishedTriangles;
auto addTriangles = [&](std::array<QPointF, 3> uvCoordinates)
{
Triangle triangle;
triangle.uvCoordinates = uvCoordinates;
triangle.fillTriangleDevicePoints(patch);
unfinishedTriangles.push_back(triangle);
};
while (!unfinishedTriangles.empty())
{
Triangle triangle = unfinishedTriangles.back();
@ -2191,13 +2195,13 @@ void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
// 3) Color difference is too high (and largest edge doesn't exceed minimal size of mesh)
// First, verify, if we can subdivide the triangle
QLineF v01(triangle.devicePoints[0], triangle.devicePoints[1]);
QLineF v02(triangle.devicePoints[0], triangle.devicePoints[2]);
QLineF v12(triangle.devicePoints[1], triangle.devicePoints[2]);
QLineF deviceLine01(triangle.devicePoints[0], triangle.devicePoints[1]);
QLineF deviceLine02(triangle.devicePoints[0], triangle.devicePoints[2]);
QLineF deviceLine12(triangle.devicePoints[1], triangle.devicePoints[2]);
const qreal length01 = v01.length();
const qreal length02 = v02.length();
const qreal length12 = v12.length();
const qreal length01 = deviceLine01.length();
const qreal length02 = deviceLine02.length();
const qreal length12 = deviceLine12.length();
const qreal maxLength = qMax(length01, qMax(length02, length12));
const PDFReal curvature = triangle.getCurvature(patch);
@ -2234,41 +2238,18 @@ void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
QPointF v1 = triangle.uvCoordinates[1];
QPointF v2 = triangle.uvCoordinates[2];
if (length12 == maxLength)
{
// We split line (v1, v2), create two triangles, (v0, v1, vx) and (v0, v2, vx), where
// vx is centerpoint of line (v1, v2).
QLineF v12uv(v1, v2);
QLineF v02uv(v0, v2);
QLineF v01uv(v0, v1);
QLineF v12(v1, v2);
QPointF vx = v12.center();
QPointF v12 = v12uv.center();
QPointF v02 = v02uv.center();
QPointF v01 = v01uv.center();
addTriangles({ v0, v1, vx });
addTriangles({ v0, v2, vx });
}
else if (length02 == maxLength)
{
// We split line (v0, v2), create two triangles, (v0, v1, vx) and (v1, v2, vx), where
// vx is centerpoint of line (v0, v2).
QLineF v02(v0, v2);
QPointF vx = v02.center();
addTriangles({ v0, v1, vx });
addTriangles({ v1, v2, vx });
}
else
{
Q_ASSERT(length01 == maxLength);
// We split line (v0, v1), create two triangles, (v0, v2, vx) and (v1, v2, vx), where
// vx is centerpoint of line (v0, v1).
QLineF v01(v0, v1);
QPointF vx = v01.center();
addTriangles({ v0, v2, vx });
addTriangles({ v1, v2, vx });
}
addTriangle(unfinishedTriangles, patch, { v0, v01, v02 });
addTriangle(unfinishedTriangles, patch, { v1, v01, v12 });
addTriangle(unfinishedTriangles, patch, { v2, v02, v12 });
addTriangle(unfinishedTriangles, patch, { v01, v02, v12 });
}
else
{
@ -2278,6 +2259,15 @@ void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
Q_ASSERT(unfinishedTriangles.empty());
// Sort the triangles according the standard (first is v direction, then u direction)
auto comparator = [](const Triangle& left, const Triangle& right)
{
QPointF leftCenter = left.getCenter();
QPointF rightCenter = right.getCenter();
return std::pair(leftCenter.y(), leftCenter.x()) < std::pair(rightCenter.y(), rightCenter.x());
};
std::sort(std::execution::parallel_policy(), finishedTriangles.begin(), finishedTriangles.end(), comparator);
std::vector<QPointF> vertices;
std::vector<PDFMesh::Triangle> triangles;
@ -2317,6 +2307,17 @@ void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
}
}
void PDFTensorProductPatchShadingBase::addTriangle(std::vector<Triangle>& triangles, const PDFTensorPatch& patch, std::array<QPointF, 3> uvCoordinates)
{
Q_ASSERT(uvCoordinates[0] != uvCoordinates[1] && uvCoordinates[1] != uvCoordinates[2]);
Triangle triangle;
triangle.uvCoordinates = uvCoordinates;
triangle.fillTriangleDevicePoints(patch);
triangles.push_back(triangle);
}
// TODO: Apply graphic state of the pattern
// TODO: Implement settings of meshing in the settings dialog
// TODO: iota - replace for PDFIntegerRange

3
PdfForQtLib/sources/pdfpattern.h
View File

@ -508,8 +508,11 @@ public:
explicit inline PDFTensorProductPatchShadingBase() = default;
protected:
struct Triangle;
void fillMesh(PDFMesh& mesh, const PDFMeshQualitySettings& settings, const PDFTensorPatch& patch) const;
void fillMesh(PDFMesh& mesh, const PDFMeshQualitySettings& settings, const PDFTensorPatches& patches) const;
static void addTriangle(std::vector<Triangle>& triangles, const PDFTensorPatch& patch, std::array<QPointF, 3> uvCoordinates);
private:
friend class PDFPattern;