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Tensor product patch shading

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This commit is contained in:
Jakub Melka 2021-03-14 15:51:06 +01:00
parent c5165186ab
commit 325db87cd5
2 changed files with 222 additions and 16 deletions
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221
Pdf4QtLib/sources/pdfpattern.cpp
View File

@ -2602,6 +2602,76 @@ QPointF PDFTensorPatch::getValue(PDFReal u, PDFReal v, int derivativeOrderU, int
return result;
}
bool PDFTensorPatch::getUV(PDFReal& u, PDFReal& v, PDFReal x, PDFReal y, PDFReal epsilon, int maximalNumberOfSteps) const
{
int i = 0;
// Jakub Melka: We are finding root of function F(u, v) defined as:
//
// F(u, v) = getValue(u, v) - (x, y)
//
// And using Newton-Raphson method to find the root
// v_n+1 = v_n - J^-1(v_n) * F(v_n)
//
// Where J^-1 is inverse of Jacobi matrix of the function F(u, v), defined as:
// dF1/du dF1/dv
// dF2/du dF2/dv
QPointF v_n(u, v);
QPointF p_xy(x, y);
while (i++ < maximalNumberOfSteps)
{
// Evaluate function at pivot
QPointF value_F_v_n = getValue(v_n.x(), v_n.y(), 0, 0) - p_xy;
// Do we actually converge?
if (qAbs(value_F_v_n.x()) < epsilon && qAbs(value_F_v_n.y()) < epsilon)
{
u = v_n.x();
v = v_n.y();
const bool uValid = u >= 0.0 && u <= 1.0;
const bool vValid = v >= 0.0 && v <= 1.0;
return uValid && vValid;
}
// Evaluate Jacobi matrix
QPointF dfdu = getValue(v_n.x(), v_n.y(), 1, 0);
QPointF dfdv = getValue(v_n.x(), v_n.y(), 0, 1);
const PDFReal m11 = dfdu.x();
const PDFReal m12 = dfdv.x();
const PDFReal m21 = dfdu.y();
const PDFReal m22 = dfdv.y();
// Create inverse of Jacobi matrix
const PDFReal determinant = m11 * m22 - m12 * m21;
if (qFuzzyIsNull(determinant))
{
// We did not converge, unfortunately, we are probably,
// in a stationary point.
return false;
}
const PDFReal inverseDeterminant = 1.0 / determinant;
const PDFReal im11 = m22 * inverseDeterminant;
const PDFReal im12 = -m12 * inverseDeterminant;
const PDFReal im21 = -m21 * inverseDeterminant;
const PDFReal im22 = m11 * inverseDeterminant;
QPointF imFirstRow(im11, im12);
QPointF imSecondRow(im21, im22);
QPointF delta(QPointF::dotProduct(imFirstRow, value_F_v_n), QPointF::dotProduct(imSecondRow, value_F_v_n));
v_n = v_n - delta;
}
return false;
}
PDFReal PDFTensorPatch::getCurvature_u(PDFReal u, PDFReal v) const
{
QPointF dSdu = getDerivative_u(u, v);
@ -2751,11 +2821,9 @@ ShadingType PDFTensorProductPatchShading::getShadingType() const
return ShadingType::TensorProductPatchMesh;
}
PDFMesh PDFTensorProductPatchShading::createMesh(const PDFMeshQualitySettings& settings, const PDFCMS* cms, RenderingIntent intent, PDFRenderErrorReporter* reporter) const
PDFTensorPatches PDFTensorProductPatchShading::createPatches(QMatrix userSpaceToDeviceSpaceMatrix, bool transformColor) const
{
PDFMesh mesh;
QMatrix patternSpaceToDeviceSpaceMatrix = getPatternSpaceToDeviceSpaceMatrix(settings);
QMatrix patternSpaceToDeviceSpaceMatrix = getPatternSpaceToDeviceSpaceMatrix(userSpaceToDeviceSpaceMatrix);
size_t bitsPerPatch = m_bitsPerFlag + 16 * 2 * m_bitsPerCoordinate + 4 * m_colorComponentCount * m_bitsPerComponent;
size_t remainder = (8 - (bitsPerPatch % 8)) % 8;
@ -2785,7 +2853,7 @@ PDFMesh PDFTensorProductPatchShading::createMesh(const PDFMeshQualitySettings& s
return patternSpaceToDeviceSpaceMatrix.map(QPointF(x, y));
};
auto readColor = [this, &reader, colorScaleRatio]() -> PDFColor
auto readColor = [this, &reader, colorScaleRatio, transformColor]() -> PDFColor
{
PDFColor color;
color.resize(m_colorComponentCount);
@ -2797,7 +2865,7 @@ PDFMesh PDFTensorProductPatchShading::createMesh(const PDFMeshQualitySettings& s
color[i] = cMin + (reader.read(m_bitsPerComponent)) * (cMax - cMin) * colorScaleRatio;
}
return getColor(color);
return transformColor ? getColor(color) : color;
};
while (!reader.isAtEnd())
@ -2966,11 +3034,26 @@ PDFMesh PDFTensorProductPatchShading::createMesh(const PDFMeshQualitySettings& s
}
default:
throw PDFException(PDFTranslationContext::tr("Invalid data in tensor product patch shading (flags = %1).").arg(flags));
patches.clear();
return patches;
}
}
fillMesh(mesh, patternSpaceToDeviceSpaceMatrix, settings, patches, cms, intent, reporter);
return patches;
}
PDFMesh PDFTensorProductPatchShading::createMesh(const PDFMeshQualitySettings& settings, const PDFCMS* cms, RenderingIntent intent, PDFRenderErrorReporter* reporter) const
{
PDFMesh mesh;
PDFTensorPatches patches = createPatches(settings.userSpaceToDeviceSpaceMatrix, true);
if (patches.empty())
{
throw PDFException(PDFTranslationContext::tr("Invalid data in tensor product patch shading."));
}
fillMesh(mesh, getPatternSpaceToDeviceSpaceMatrix(settings.userSpaceToDeviceSpaceMatrix), settings, patches, cms, intent, reporter);
return mesh;
}
@ -3015,6 +3098,99 @@ struct PDFTensorProductPatchShadingBase::Triangle
}
};
class PDFTensorPatchesSample : public PDFShadingSampler
{
public:
PDFTensorPatchesSample(const PDFTensorProductPatchShadingBase* shadingPattern, QMatrix userSpaceToDeviceSpaceMatrix) :
PDFShadingSampler(shadingPattern),
m_tensorProductShadingPattern(shadingPattern)
{
m_patches = shadingPattern->createPatches(userSpaceToDeviceSpaceMatrix, false);
std::reverse(m_patches.begin(), m_patches.end());
}
virtual bool sample(const QPointF& devicePoint, PDFColorBuffer outputBuffer, int limit) const override
{
constexpr PDFReal epsilon = 0.001;
std::array initialSamples = { QPointF(0.5, 0.5) };
for (const PDFTensorPatch& patch : m_patches)
{
PDFReal u = -1.0;
PDFReal v = -1.0;
for (const QPointF& initialSample : initialSamples)
{
PDFReal uSample = initialSample.x();
PDFReal vSample = initialSample.y();
if (patch.getUV(uSample, vSample, devicePoint.x(), devicePoint.y(), epsilon, limit))
{
// We have successfully retrieved u,v source for the target x,y point. But is it actually
// better than previous sample?
if (vSample > v || (qAbs(vSample - v) < epsilon && uSample > u))
{
u = uSample;
v = vSample;
}
}
}
if (u >= 0.0 && v >= 0.0)
{
const PDFTensorPatch::Colors& colors = patch.getColors();
const PDFColor& topLeft = colors[PDFTensorPatch::C_00];
const PDFColor& topRight = colors[PDFTensorPatch::C_30];
const PDFColor& bottomLeft = colors[PDFTensorPatch::C_03];
const PDFColor& bottomRight = colors[PDFTensorPatch::C_33];
PDFColor color;
color.resize(topLeft.size());
const size_t colorComponentCount = color.size();
for (size_t i = 0; i < colorComponentCount; ++i)
{
color[i] = topLeft[i] * (1.0 - u) * (1.0 - v) +
topRight[i] * u * (1.0 - v) +
bottomLeft[i] * (1.0 - u) * v +
bottomRight[i] * u * v;
}
PDFColor finalColor = m_tensorProductShadingPattern->getColor(color);
if (finalColor.size() != outputBuffer.size())
{
return false;
}
for (size_t i = 0; i < finalColor.size(); ++i)
{
outputBuffer[i] = finalColor[i];
}
return true;
}
}
return false;
}
private:
const PDFTensorProductPatchShadingBase* m_tensorProductShadingPattern;
PDFTensorPatches m_patches;
};
PDFShadingSampler* PDFTensorProductPatchShadingBase::createSampler(QMatrix userSpaceToDeviceSpaceMatrix) const
{
PDFTensorPatches patches = createPatches(userSpaceToDeviceSpaceMatrix, false);
if (patches.empty())
{
return nullptr;
}
return new PDFTensorPatchesSample(this, userSpaceToDeviceSpaceMatrix);
}
void PDFTensorProductPatchShadingBase::fillMesh(PDFMesh& mesh,
const PDFMeshQualitySettings& settings,
const PDFTensorPatch& patch,
@ -3242,11 +3418,9 @@ ShadingType PDFCoonsPatchShading::getShadingType() const
return ShadingType::CoonsPatchMesh;
}
PDFMesh PDFCoonsPatchShading::createMesh(const PDFMeshQualitySettings& settings, const PDFCMS* cms, RenderingIntent intent, PDFRenderErrorReporter* reporter) const
PDFTensorPatches PDFCoonsPatchShading::createPatches(QMatrix userSpaceToDeviceSpaceMatrix, bool transformColor) const
{
PDFMesh mesh;
QMatrix patternSpaceToDeviceSpaceMatrix = getPatternSpaceToDeviceSpaceMatrix(settings);
QMatrix patternSpaceToDeviceSpaceMatrix = getPatternSpaceToDeviceSpaceMatrix(userSpaceToDeviceSpaceMatrix);
size_t bitsPerPatch = m_bitsPerFlag + 16 * 2 * m_bitsPerCoordinate + 4 * m_colorComponentCount * m_bitsPerComponent;
size_t remainder = (8 - (bitsPerPatch % 8)) % 8;
@ -3276,7 +3450,7 @@ PDFMesh PDFCoonsPatchShading::createMesh(const PDFMeshQualitySettings& settings,
return patternSpaceToDeviceSpaceMatrix.map(QPointF(x, y));
};
auto readColor = [this, &reader, colorScaleRatio]() -> PDFColor
auto readColor = [this, &reader, colorScaleRatio, transformColor]() -> PDFColor
{
PDFColor color;
color.resize(m_colorComponentCount);
@ -3288,7 +3462,7 @@ PDFMesh PDFCoonsPatchShading::createMesh(const PDFMeshQualitySettings& settings,
color[i] = cMin + (reader.read(m_bitsPerComponent)) * (cMax - cMin) * colorScaleRatio;
}
return getColor(color);
return transformColor ? getColor(color) : color;
};
std::array<QPointF, 12> vertices;
@ -3432,11 +3606,26 @@ PDFMesh PDFCoonsPatchShading::createMesh(const PDFMeshQualitySettings& settings,
}
default:
throw PDFException(PDFTranslationContext::tr("Invalid data in coons patch shading (flags = %1).").arg(flags));
// This is error, clear patches and return
patches.clear();
return patches;
}
}
fillMesh(mesh, patternSpaceToDeviceSpaceMatrix, settings, patches, cms, intent, reporter);
return patches;
}
PDFMesh PDFCoonsPatchShading::createMesh(const PDFMeshQualitySettings& settings, const PDFCMS* cms, RenderingIntent intent, PDFRenderErrorReporter* reporter) const
{
PDFMesh mesh;
PDFTensorPatches patches = createPatches(settings.userSpaceToDeviceSpaceMatrix, true);
if (patches.empty())
{
throw PDFException(PDFTranslationContext::tr("Invalid data in coons patch shading."));
}
fillMesh(mesh, getPatternSpaceToDeviceSpaceMatrix(settings), settings, patches, cms, intent, reporter);
return mesh;
}

17
Pdf4QtLib/sources/pdfpattern.h
View File

@ -561,6 +561,18 @@ public:
/// \param derivativeOrderV Derivation order in direction v (0 means no derivation)
QPointF getValue(PDFReal u, PDFReal v, int derivativeOrderU, int derivativeOrderV) const;
/// Tries to find value (u,v) using Newton-Raphson numerical algorithm method.
/// This can fail and when it fails, false is returned. As initial point, input uv
/// is considered. Also, if maximal number of steps is reached, false is returned.
/// \param[in,out] u Output value of u (passed value is used as a seed)
/// \param[in,out] v Output value of v (passed value is used as a seed)
/// \param x Input x coordinate, for which we want to compute (u, v)
/// \param y Input y coordinate, for which we want to compute (u, v)
/// \param epsilon Epsilon, when distance from the getValue(u, v) and (x, y)
/// is less than epsilon, convergence is reached
/// \param maximalNumberOfSteps Maximal number of steps of Newton-Raphson algorithm
bool getUV(PDFReal& u, PDFReal& v, PDFReal x, PDFReal y, PDFReal epsilon, int maximalNumberOfSteps) const;
/// Calculates first derivate in the surface, in the direction of variable u.
/// \param u Horizontal coordinate of the patch, must be in range [0, 1]
/// \param v Vertical coordinate of the patch, must be in range [0, 1]
@ -653,6 +665,9 @@ class PDFTensorProductPatchShadingBase : public PDFType4567Shading
public:
explicit inline PDFTensorProductPatchShadingBase() = default;
virtual PDFShadingSampler* createSampler(QMatrix userSpaceToDeviceSpaceMatrix) const override;
virtual PDFTensorPatches createPatches(QMatrix userSpaceToDeviceSpaceMatrix, bool transformColor) const = 0;
protected:
struct Triangle;
@ -671,6 +686,7 @@ public:
virtual ShadingType getShadingType() const override;
virtual PDFMesh createMesh(const PDFMeshQualitySettings& settings, const PDFCMS* cms, RenderingIntent intent, PDFRenderErrorReporter* reporter) const override;
virtual PDFTensorPatches createPatches(QMatrix userSpaceToDeviceSpaceMatrix, bool transformColor) const override;
private:
friend class PDFPattern;
@ -683,6 +699,7 @@ public:
virtual ShadingType getShadingType() const override;
virtual PDFMesh createMesh(const PDFMeshQualitySettings& settings, const PDFCMS* cms, RenderingIntent intent, PDFRenderErrorReporter* reporter) const override;
virtual PDFTensorPatches createPatches(QMatrix userSpaceToDeviceSpaceMatrix, bool transformColor) const override;
private:
friend class PDFPattern;