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Diffstat (limited to 'Source/WebCore/platform/graphics/gpu/LoopBlinnPathProcessor.cpp')
| -rw-r--r-- | Source/WebCore/platform/graphics/gpu/LoopBlinnPathProcessor.cpp | 1228 |
1 files changed, 1228 insertions, 0 deletions
diff --git a/Source/WebCore/platform/graphics/gpu/LoopBlinnPathProcessor.cpp b/Source/WebCore/platform/graphics/gpu/LoopBlinnPathProcessor.cpp new file mode 100644 index 0000000..e84ddbf --- /dev/null +++ b/Source/WebCore/platform/graphics/gpu/LoopBlinnPathProcessor.cpp @@ -0,0 +1,1228 @@ +/* + * Copyright (C) 2011 Google Inc. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE + * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; + * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND + * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "config.h" + +#include "LoopBlinnPathProcessor.h" + +#include "FloatPoint.h" +#include "FloatRect.h" +#include "LoopBlinnClassifier.h" +#include "LoopBlinnConstants.h" +#include "LoopBlinnLocalTriangulator.h" +#include "LoopBlinnMathUtils.h" +#include "LoopBlinnPathCache.h" +#include "LoopBlinnTextureCoords.h" +#include "PODArena.h" +#include "PODIntervalTree.h" +#include "Path.h" +#include "internal_glu.h" +#include <algorithm> +#include <wtf/Assertions.h> +#include <wtf/FastMalloc.h> + +#if PLATFORM(SKIA) +#include "SkGeometry.h" +#include "SkPath.h" +#include "SkScalar.h" +#else +// Must port to your platform. +#endif + +namespace WebCore { + +using LoopBlinnMathUtils::XRay; +using LoopBlinnMathUtils::chopCubicAt; +using LoopBlinnMathUtils::numXRayCrossingsForCubic; +using LoopBlinnMathUtils::trianglesOverlap; +using LoopBlinnMathUtils::xRayCrossesLine; +using LoopBlinnPathProcessorImplementation::Contour; +using LoopBlinnPathProcessorImplementation::Segment; + +namespace { + +#ifndef NDEBUG +String valueToString(const FloatRect& arg) +{ + StringBuilder builder; + builder.append("[FloatRect x="); + builder.append(String::number(arg.x())); + builder.append(" y="); + builder.append(String::number(arg.y())); + builder.append(" maxX="); + builder.append(String::number(arg.maxX())); + builder.append(" maxY="); + builder.append(String::number(arg.maxY())); + builder.append("]"); + return builder.toString(); +} +#endif + +struct SweepData; + +} // anonymous namespace + +namespace LoopBlinnPathProcessorImplementation { +class Segment; +} + +#ifndef NDEBUG +// Routines needed to print the types of IntervalNodes we instantiate +// in this file. +template <> +struct ValueToString<float> { + static String string(const float& value) + { + return String::number(value); + } +}; + +template <> +struct ValueToString<SweepData*> { + static String string(SweepData* const& value) + { + return String::format("0x%p", value); + } +}; + +template <> +struct ValueToString<LoopBlinnPathProcessorImplementation::Segment*> { + static String string(LoopBlinnPathProcessorImplementation::Segment* const& value) + { + return String::format("0x%p", value); + } +}; +#endif + +namespace LoopBlinnPathProcessorImplementation { + +//---------------------------------------------------------------------- +// Segment +// + +// Describes a segment of the path: either a cubic or a line segment. +// These are stored in a doubly linked list to speed up curve +// subdivision, which occurs due to either rendering artifacts in the +// loop case or due to overlapping triangles. +class Segment { + WTF_MAKE_NONCOPYABLE(Segment); +public: + enum Kind { + Cubic, + Line + }; + + // No-argument constructor allows construction by the PODArena class. + Segment() + : m_arena(0) + , m_kind(Cubic) + , m_prev(0) + , m_next(0) + , m_contour(0) + , m_triangulator(0) + , m_markedForSubdivision(false) + { + } + + // Initializer for cubic curve segments. + void setup(PODArena* arena, + Contour* contour, + FloatPoint cp0, + FloatPoint cp1, + FloatPoint cp2, + FloatPoint cp3) + { + m_arena = arena; + m_contour = contour; + m_kind = Cubic; + m_points[0] = cp0; + m_points[1] = cp1; + m_points[2] = cp2; + m_points[3] = cp3; + computeBoundingBox(); + } + + // Initializer for line segments. + void setup(PODArena* arena, + Contour* contour, + FloatPoint p0, + FloatPoint p1) + { + m_arena = arena; + m_contour = contour; + m_kind = Line; + m_points[0] = p0; + m_points[1] = p1; + computeBoundingBox(); + } + + Kind kind() const { return m_kind; } + + // Returns the i'th control point, 0 <= i < 4. + const FloatPoint& getPoint(int i) + { + ASSERT(i >= 0 && i < 4); + return m_points[i]; + } + + Segment* next() const { return m_next; } + Segment* prev() const { return m_prev; } + + void setNext(Segment* next) { m_next = next; } + void setPrev(Segment* prev) { m_prev = prev; } + + // The contour this segment belongs to. + Contour* contour() const { return m_contour; } + + // Subdivides the current segment at the given parameter value (0 <= + // t <= 1) and replaces it with the two newly created Segments in + // the linked list, if possible. Returns a pointer to the leftmost + // Segment. + Segment* subdivide(float param) + { + FloatPoint dst[7]; + chopCubicAt(m_points, dst, param); + Segment* left = m_arena->allocateObject<Segment>(); + Segment* right = m_arena->allocateObject<Segment>(); + left->setup(m_arena, m_contour, dst[0], dst[1], dst[2], dst[3]); + right->setup(m_arena, m_contour, dst[3], dst[4], dst[5], dst[6]); + left->setNext(right); + right->setPrev(left); + // Try to set up a link between "this->prev()" and "left". + if (prev()) { + left->setPrev(prev()); + prev()->setNext(left); + } + // Try to set up a link between "this->next()" and "right". + Segment* n = next(); + if (n) { + right->setNext(n); + n->setPrev(right); + } + // Set up a link between "this" and "left"; this is only to + // provide a certain amount of continuity during forward iteration. + setNext(left); + return left; + } + + // Subdivides the current segment at the halfway point and replaces + // it with the two newly created Segments in the linked list, if + // possible. Returns a pointer to the leftmost Segment. + Segment* subdivide() { return subdivide(0.5f); } + + const FloatRect& boundingBox() const { return m_boundingBox; } + + // Computes the number of times a query line starting at the given + // point and extending to x=+infinity crosses this segment. Outgoing + // "ambiguous" argument indicates whether the query intersected an + // endpoint or tangent point of the segment, indicating that another + // query point is preferred. + int numCrossingsForXRay(const XRay& xRay, bool& ambiguous) const + { + if (m_kind == Cubic) + // Should consider caching the monotonic cubics. + return numXRayCrossingsForCubic(xRay, m_points, ambiguous); + + return xRayCrossesLine(xRay, m_points, ambiguous) ? 1 : 0; + } + + // Performs a local triangulation of the control points in this + // segment. This operation only makes sense for cubic type segments. + // texCoords may be null when the klm coordinates have not been + // computed yet. + void triangulate(LoopBlinnLocalTriangulator::InsideEdgeComputation computeInsideEdges, + const LoopBlinnTextureCoords::Result* texCoords); + + // Returns the number of control point triangles associated with + // this segment. + int numberOfTriangles() const + { + if (!m_triangulator) + return 0; + return m_triangulator->numberOfTriangles(); + } + + // Fetches the given control point triangle for this segment. + LoopBlinnLocalTriangulator::Triangle* getTriangle(int index) + { + ASSERT(m_triangulator); + return m_triangulator->getTriangle(index); + } + + // Number of vertices along the inside edge of this segment. This + // can be called either for line or cubic type segments. + int numberOfInteriorVertices() const + { + if (m_kind == Cubic) { + if (m_triangulator) + return m_triangulator->numberOfInteriorVertices(); + + return 0; + } + + return 2; + } + + // Returns the given interior vertex, 0 <= index < numberOfInteriorVertices(). + FloatPoint getInteriorVertex(int index) const + { + ASSERT(index >= 0 && index < numberOfInteriorVertices()); + if (m_kind == Cubic) { + FloatPoint res; + if (m_triangulator) { + LoopBlinnLocalTriangulator::Vertex* vertex = m_triangulator->getInteriorVertex(index); + if (vertex) + res.set(vertex->xyCoordinates().x(), vertex->xyCoordinates().y()); + } + return res; + } + + return m_points[index]; + } + + // State to assist with curve subdivision. + bool markedForSubdivision() const { return m_markedForSubdivision; } + void setMarkedForSubdivision(bool markedForSubdivision) { m_markedForSubdivision = markedForSubdivision; } + +#ifndef NDEBUG + // Suppport for printing Segments. + String toString() const + { + StringBuilder builder; + builder.append("[Segment kind="); + builder.append(kind() == Line ? "line" : "cubic"); + builder.append(" boundingBox="); + builder.append(valueToString(boundingBox())); + builder.append(" contour=0x"); + builder.append(String::format("%p", contour())); + builder.append(" markedForSubdivision="); + builder.append(markedForSubdivision() ? "true" : "false"); + builder.append("]"); + return builder.toString(); + } +#endif + + private: + // Computes the bounding box of this Segment. + void computeBoundingBox() + { + switch (m_kind) { + case Cubic: + m_boundingBox.fitToPoints(m_points[0], m_points[1], m_points[2], m_points[3]); + break; + + case Line: + m_boundingBox.fitToPoints(m_points[0], m_points[1]); + break; + } + } + + PODArena* m_arena; + Kind m_kind; + FloatPoint m_points[4]; + Segment* m_prev; + Segment* m_next; + Contour* m_contour; + FloatRect m_boundingBox; + LoopBlinnLocalTriangulator* m_triangulator; + bool m_markedForSubdivision; +}; + +//---------------------------------------------------------------------- +// Contour +// + +// Describes a closed contour of the path. +class Contour { + WTF_MAKE_NONCOPYABLE(Contour); +public: + Contour() + { + m_first = &m_sentinel; + m_first->setNext(m_first); + m_first->setPrev(m_first); + m_isOrientedCounterClockwise = true; + m_boundingBoxDirty = false; + m_fillSide = LoopBlinnConstants::RightSide; + } + + void add(Segment* segment) + { + if (m_first == &m_sentinel) { + // First element is the sentinel. Replace it with the incoming + // segment. + segment->setNext(m_first); + segment->setPrev(m_first); + m_first->setNext(segment); + m_first->setPrev(segment); + m_first = segment; + } else { + // m_first->prev() is the sentinel. + ASSERT(m_first->prev() == &m_sentinel); + Segment* last = m_sentinel.prev(); + last->setNext(segment); + segment->setPrev(last); + segment->setNext(&m_sentinel); + m_sentinel.setPrev(segment); + } + m_boundingBoxDirty = true; + } + + // Subdivides the given segment at the given parametric value. + // Returns a pointer to the first of the two portions of the + // subdivided segment. + Segment* subdivide(Segment* segment, float param) + { + Segment* left = segment->subdivide(param); + if (m_first == segment) + m_first = left; + return left; + } + + // Subdivides the given segment at the halfway point. Returns a + // pointer to the first of the two portions of the subdivided + // segment. + Segment* subdivide(Segment* segment) + { + Segment* left = segment->subdivide(); + if (m_first == segment) + m_first = left; + return left; + } + + // Returns the first segment in the contour for iteration. + Segment* begin() const { return m_first; } + + // Returns the last segment in the contour for iteration. Callers + // should not iterate over this segment. In other words: + // for (Segment* cur = contour->begin(); + // cur != contour->end(); + // cur = cur->next()) { + // // .. process cur ... + // } + Segment* end() + { + ASSERT(m_first->prev() == &m_sentinel); + return &m_sentinel; + } + + bool isOrientedCounterClockwise() const { return m_isOrientedCounterClockwise; } + void setIsOrientedCounterClockwise(bool isOrientedCounterClockwise) { m_isOrientedCounterClockwise = isOrientedCounterClockwise; } + + const FloatRect& boundingBox() + { + if (m_boundingBoxDirty) { + bool first = true; + for (Segment* cur = begin(); cur != end(); cur = cur->next()) { + if (first) + m_boundingBox = cur->boundingBox(); + else + m_boundingBox.unite(cur->boundingBox()); + first = false; + } + + m_boundingBoxDirty = false; + } + return m_boundingBox; + } + + // Returns which side of this contour is filled. + LoopBlinnConstants::FillSide fillSide() const + { + return m_fillSide; + } + + void setFillSide(LoopBlinnConstants::FillSide fillSide) + { + m_fillSide = fillSide; + } + +private: + // The start of the segment chain. The segments are kept in a + // circular doubly linked list for rapid access to the beginning and + // end. + Segment* m_first; + + // The sentinel element at the end of the chain, needed for + // reasonable iteration semantics. + Segment m_sentinel; + + bool m_isOrientedCounterClockwise; + + FloatRect m_boundingBox; + bool m_boundingBoxDirty; + + // Which side of this contour should be filled. + LoopBlinnConstants::FillSide m_fillSide; +}; + +//---------------------------------------------------------------------- +// Segment +// + +// Definition of Segment::triangulate(), which must come after +// declaration of Contour. +void Segment::triangulate(LoopBlinnLocalTriangulator::InsideEdgeComputation computeInsideEdges, + const LoopBlinnTextureCoords::Result* texCoords) +{ + ASSERT(m_kind == Cubic); + if (!m_triangulator) + m_triangulator = m_arena->allocateObject<LoopBlinnLocalTriangulator>(); + m_triangulator->reset(); + for (int i = 0; i < 4; i++) { + LoopBlinnLocalTriangulator::Vertex* vertex = m_triangulator->getVertex(i); + if (texCoords) { + vertex->set(getPoint(i).x(), + getPoint(i).y(), + texCoords->klmCoordinates[i].x(), + texCoords->klmCoordinates[i].y(), + texCoords->klmCoordinates[i].z()); + } else { + vertex->set(getPoint(i).x(), + getPoint(i).y(), + // No texture coordinates yet + 0, 0, 0); + } + } + m_triangulator->triangulate(computeInsideEdges, contour()->fillSide()); +} + +} // namespace LoopBlinnPathProcessorImplementation + +//---------------------------------------------------------------------- +// LoopBlinnPathProcessor +// + +LoopBlinnPathProcessor::LoopBlinnPathProcessor() + : m_arena(PODArena::create()) +#ifndef NDEBUG + , m_verboseLogging(false) +#endif +{ +} + +LoopBlinnPathProcessor::LoopBlinnPathProcessor(PassRefPtr<PODArena> arena) + : m_arena(arena) +#ifndef NDEBUG + , m_verboseLogging(false) +#endif +{ +} + +LoopBlinnPathProcessor::~LoopBlinnPathProcessor() +{ +} + +void LoopBlinnPathProcessor::process(const Path& path, LoopBlinnPathCache& cache) +{ + buildContours(path); + + // Run plane-sweep algorithm to determine overlaps of control point + // curves and subdivide curves appropriately. + subdivideCurves(); + + // Determine orientations of countours. Based on orientation and the + // number of curve crossings at a random point on the contour, + // determine whether to fill the left or right side of the contour. + determineSidesToFill(); + + // Classify curves, compute texture coordinates and subdivide as + // necessary to eliminate rendering artifacts. Do the final + // triangulation of the curve segments, determining the path along + // the interior of the shape. + for (Vector<Contour*>::iterator iter = m_contours.begin(); iter != m_contours.end(); ++iter) { + Contour* cur = *iter; + for (Segment* seg = cur->begin(); seg != cur->end(); seg = seg->next()) { + if (seg->kind() == Segment::Cubic) { + LoopBlinnClassifier::Result classification = LoopBlinnClassifier::classify(seg->getPoint(0), + seg->getPoint(1), + seg->getPoint(2), + seg->getPoint(3)); +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("Classification: %d", (int) classification.curveType); +#endif + LoopBlinnTextureCoords::Result texCoords = + LoopBlinnTextureCoords::compute(classification, cur->fillSide()); + if (texCoords.hasRenderingArtifact) { + // FIXME: there is a problem where the algorithm + // sometimes fails to converge when splitting at the + // subdivision parameter value. For the time being, + // split halfway. + cur->subdivide(seg); + // Next iteration will handle the newly subdivided curves + } else { + if (!texCoords.isLineOrPoint) { + seg->triangulate(LoopBlinnLocalTriangulator::ComputeInsideEdges, &texCoords); + for (int i = 0; i < seg->numberOfTriangles(); i++) { + LoopBlinnLocalTriangulator::Triangle* triangle = seg->getTriangle(i); + for (int j = 0; j < 3; j++) { + LoopBlinnLocalTriangulator::Vertex* vert = triangle->getVertex(j); + cache.addVertex(vert->xyCoordinates().x(), + vert->xyCoordinates().y(), + vert->klmCoordinates().x(), + vert->klmCoordinates().y(), + vert->klmCoordinates().z()); + } + } +#ifdef LOOP_BLINN_PATH_CACHE_DEBUG_INTERIOR_EDGES + // Show the end user the interior edges as well + for (int i = 1; i < seg->numberOfInteriorVertices(); i++) { + FloatPoint vert = seg->getInteriorVertex(i); + // Duplicate previous vertex to be able to draw GL_LINES + FloatPoint prev = seg->getInteriorVertex(i - 1); + cache.addInteriorEdgeVertex(prev.x(), prev.y()); + cache.addInteriorEdgeVertex(vert.x(), vert.y()); + } +#endif // LOOP_BLINN_PATH_CACHE_DEBUG_INTERIOR_EDGES + } + } + } + } + } + + // Run the interior paths through a tessellation algorithm + // supporting multiple contours. + tessellateInterior(cache); +} + +void LoopBlinnPathProcessor::buildContours(const Path& path) +{ + // Clear out the contours + m_contours.clear(); +#if PLATFORM(SKIA) + SkPath::Iter iter(*path.platformPath(), false); + SkPoint points[4]; + SkPath::Verb verb; + Contour* contour = 0; + SkPoint curPoint = { 0 }; + SkPoint moveToPoint = { 0 }; + do { + verb = iter.next(points); + if (verb != SkPath::kMove_Verb) { + if (!contour) { + contour = m_arena->allocateObject<Contour>(); + m_contours.append(contour); + } + } + switch (verb) { + case SkPath::kMove_Verb: { + contour = m_arena->allocateObject<Contour>(); + m_contours.append(contour); + curPoint = points[0]; + moveToPoint = points[0]; +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("MoveTo (%f, %f)", points[0].fX, points[0].fY); +#endif + break; + } + case SkPath::kLine_Verb: { + Segment* segment = m_arena->allocateObject<Segment>(); + if (iter.isCloseLine()) { + segment->setup(m_arena.get(), contour, curPoint, points[1]); +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("CloseLineTo (%f, %f), (%f, %f)", curPoint.fX, curPoint.fY, points[1].fX, points[1].fY); +#endif + contour->add(segment); + contour = 0; + } else { + segment->setup(m_arena.get(), contour, points[0], points[1]); +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("LineTo (%f, %f), (%f, %f)", points[0].fX, points[0].fY, points[1].fX, points[1].fY); +#endif + contour->add(segment); + curPoint = points[1]; + } + break; + } + case SkPath::kQuad_Verb: { + // Need to degree elevate the quadratic into a cubic + SkPoint cubic[4]; + SkConvertQuadToCubic(points, cubic); + Segment* segment = m_arena->allocateObject<Segment>(); + segment->setup(m_arena.get(), contour, + cubic[0], cubic[1], cubic[2], cubic[3]); +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("Quad->CubicTo (%f, %f), (%f, %f), (%f, %f), (%f, %f)", cubic[0].fX, cubic[0].fY, cubic[1].fX, cubic[1].fY, cubic[2].fX, cubic[2].fY, cubic[3].fX, cubic[3].fY); +#endif + contour->add(segment); + curPoint = cubic[3]; + break; + } + case SkPath::kCubic_Verb: { + Segment* segment = m_arena->allocateObject<Segment>(); + segment->setup(m_arena.get(), contour, points[0], points[1], points[2], points[3]); +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("CubicTo (%f, %f), (%f, %f), (%f, %f), (%f, %f)", points[0].fX, points[0].fY, points[1].fX, points[1].fY, points[2].fX, points[2].fY, points[3].fX, points[3].fY); +#endif + contour->add(segment); + curPoint = points[3]; + break; + } + case SkPath::kClose_Verb: { + Segment* segment = m_arena->allocateObject<Segment>(); + segment->setup(m_arena.get(), contour, curPoint, moveToPoint); +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("Close (%f, %f) -> (%f, %f)", curPoint.fX, curPoint.fY, moveToPoint.fX, moveToPoint.fY); +#endif + contour->add(segment); + contour = 0; + } + case SkPath::kDone_Verb: + break; + } + } while (verb != SkPath::kDone_Verb); +#else // !PLATFORM(SKIA) + // Must port to your platform. + ASSERT_NOT_REACHED(); +#endif +} + +#ifndef NDEBUG +Vector<Segment*> LoopBlinnPathProcessor::allSegmentsOverlappingY(Contour* queryContour, float x, float y) +{ + Vector<Segment*> res; + for (Vector<Contour*>::iterator iter = m_contours.begin(); iter != m_contours.end(); ++iter) { + Contour* cur = *iter; + for (Segment* seg = cur->begin(); seg != cur->end(); seg = seg->next()) { + const FloatRect& boundingBox = seg->boundingBox(); + if (boundingBox.y() <= y && y <= boundingBox.maxY()) + res.append(seg); + } + } + return res; +} +#endif + +// Uncomment this to debug the orientation computation. +// #define GPU_PATH_PROCESSOR_DEBUG_ORIENTATION + +void LoopBlinnPathProcessor::determineSidesToFill() +{ + // Loop and Blinn's algorithm can only easily emulate the even/odd + // fill rule, and only for non-intersecting curves. We can determine + // which side of each curve segment to fill based on its + // clockwise/counterclockwise orientation and how many other + // contours surround it. + + // To optimize the query of all curve segments intersecting a + // horizontal line going to x=+infinity, we build up an interval + // tree whose keys are the y extents of the segments. + PODIntervalTree<float, Segment*> tree(m_arena); + typedef PODIntervalTree<float, Segment*>::IntervalType IntervalType; + + for (Vector<Contour*>::iterator iter = m_contours.begin(); iter != m_contours.end(); ++iter) { + Contour* cur = *iter; + determineOrientation(cur); + for (Segment* seg = cur->begin(); seg != cur->end(); seg = seg->next()) { + const FloatRect& boundingBox = seg->boundingBox(); + tree.add(tree.createInterval(boundingBox.y(), boundingBox.maxY(), seg)); + } + } + + // Now iterate through the contours and pick a random segment (in + // this case we use the first) and a random point on that segment. + // Find all segments from other contours which intersect this one + // and count the number of crossings a horizontal line to + // x=+infinity makes with those contours. This combined with the + // orientation of the curve tells us which side to fill -- again, + // assuming an even/odd fill rule, which is all we can easily + // handle. + for (Vector<Contour*>::iterator iter = m_contours.begin(); iter != m_contours.end(); ++iter) { + Contour* cur = *iter; + + bool ambiguous = true; + int numCrossings = 0; + + // For each contour, attempt to find a point on the contour which, + // when we cast an XRay, does not intersect the other contours at + // an ambiguous point (the junction between two curves or at a + // tangent point). Ambiguous points make the determination of + // whether this contour is contained within another fragile. Note + // that this loop is only an approximation to the selection of a + // good casting point. We could as well evaluate a segment to + // determine a point upon it. + for (Segment* seg = cur->begin(); + ambiguous && seg != cur->end(); + seg = seg->next()) { + numCrossings = 0; + // We use a zero-sized vertical interval for the query. + Vector<IntervalType> overlaps = tree.allOverlaps(tree.createInterval(seg->getPoint(0).y(), + seg->getPoint(0).y(), + 0)); +#if defined(GPU_PATH_PROCESSOR_DEBUG_ORIENTATION) && !defined(NDEBUG) + Vector<Segment*> slowOverlaps = allSegmentsOverlappingY(cur, seg->getPoint(0).x(), seg->getPoint(0).y()); + if (overlaps.size() != slowOverlaps.size()) { + LOG_ERROR("For query point (%f, %f) on contour 0x%p:", seg->getPoint(0).x(), seg->getPoint(0).y(), cur); + LOG_ERROR(" overlaps:"); + for (size_t i = 0; i < overlaps.size(); i++) + LOG_ERROR(" %d: %s", i+1, overlaps[i].data()->toString().ascii().data()); + LOG_ERROR(" slowOverlaps:"); + for (size_t i = 0; i < slowOverlaps.size(); i++) + LOG_ERROR(" %d: %s", (i+1) slowOverlaps[i]->toString()); + LOG_ERROR("Interval tree:"); + tree.dump(); + } + ASSERT(overlaps.size() == slowOverlaps.size()); +#endif // defined(GPU_PATH_PROCESSOR_DEBUG_ORIENTATION) && !defined(NDEBUG) + for (Vector<IntervalType>::iterator iter = overlaps.begin(); iter != overlaps.end(); ++iter) { + const IntervalType& interval = *iter; + Segment* querySegment = interval.data(); + // Ignore segments coming from the same contour. + if (querySegment->contour() != cur) { + // Only perform queries that can affect the computation. + const FloatRect& boundingBox = querySegment->contour()->boundingBox(); + if (seg->getPoint(0).x() >= boundingBox.x() + && seg->getPoint(0).x() <= boundingBox.maxX()) { + numCrossings += querySegment->numCrossingsForXRay(seg->getPoint(0), + ambiguous); + if (ambiguous) { +#ifndef NDEBUG + if (m_verboseLogging) { + LOG_ERROR("Ambiguous intersection query at point (%f, %f)", seg->getPoint(0).x(), seg->getPoint(0).y()); + LOG_ERROR("Query segment: %s", querySegment->toString().ascii().data()); + } +#endif + break; // Abort iteration over overlaps. + } + } + } + } + } // for (Segment* seg = cur->begin(); ... + + cur->setFillSide((cur->isOrientedCounterClockwise() ^ (numCrossings & 1)) ? LoopBlinnConstants::LeftSide : LoopBlinnConstants::RightSide); + } +} + +void LoopBlinnPathProcessor::determineOrientation(Contour* contour) +{ + // Determine signed area of the polygon represented by the points + // along the segments. Consider this an approximation to the true + // orientation of the polygon; it probably won't handle + // self-intersecting curves correctly. + // + // There is also a pretty basic assumption here that the contour is + // closed. + float signedArea = 0; + for (Segment* seg = contour->begin(); + seg != contour->end(); + seg = seg->next()) { + int limit = (seg->kind() == Segment::Cubic) ? 4 : 2; + for (int i = 1; i < limit; i++) { + const FloatPoint& prevPoint = seg->getPoint(i - 1); + const FloatPoint& point = seg->getPoint(i); + float curArea = prevPoint.x() * point.y() - prevPoint.y() * point.x(); +#ifndef NDEBUG + if (m_verboseLogging) + LOG_ERROR("Adding to signed area (%f, %f) -> (%f, %f) = %f", prevPoint.x(), prevPoint.y(), point.x(), point.y(), curArea); +#endif + signedArea += curArea; + } + } + + if (signedArea > 0) + contour->setIsOrientedCounterClockwise(true); + else + contour->setIsOrientedCounterClockwise(false); +} + +namespace { + +//---------------------------------------------------------------------- +// Classes and typedefs needed for curve subdivision. These can't be scoped +// within the subdivideCurves() method itself, because templates then fail +// to instantiate. + +// The user data which is placed in the PODIntervalTree. +struct SweepData { + SweepData() + : triangle(0) + , segment(0) + { + } + + // The triangle this interval is associated with + LoopBlinnLocalTriangulator::Triangle* triangle; + // The segment the triangle is associated with + Segment* segment; +}; + +typedef PODIntervalTree<float, SweepData*> SweepTree; +typedef SweepTree::IntervalType SweepInterval; + +// The entry / exit events which occur at the minimum and maximum x +// coordinates of the control point triangles' bounding boxes. +// +// Note that this class requires its copy constructor and assignment +// operator since it needs to be stored in a Vector. +class SweepEvent { +public: + SweepEvent() + : m_x(0) + , m_entry(false) + , m_interval(0, 0, 0) + { + } + + // Initializes the SweepEvent. + void setup(float x, bool entry, SweepInterval interval) + { + m_x = x; + m_entry = entry; + m_interval = interval; + } + + float x() const { return m_x; } + bool entry() const { return m_entry; } + const SweepInterval& interval() const { return m_interval; } + + bool operator<(const SweepEvent& other) const + { + return m_x < other.m_x; + } + +private: + float m_x; + bool m_entry; + SweepInterval m_interval; +}; + +bool trianglesOverlap(LoopBlinnLocalTriangulator::Triangle* t0, + LoopBlinnLocalTriangulator::Triangle* t1) +{ + return trianglesOverlap(t0->getVertex(0)->xyCoordinates(), + t0->getVertex(1)->xyCoordinates(), + t0->getVertex(2)->xyCoordinates(), + t1->getVertex(0)->xyCoordinates(), + t1->getVertex(1)->xyCoordinates(), + t1->getVertex(2)->xyCoordinates()); +} + +} // anonymous namespace + +void LoopBlinnPathProcessor::subdivideCurves() +{ + // We need to determine all overlaps of all control point triangles + // (from different segments, not the same segment) and, if any + // exist, subdivide the associated curves. + // + // The plane-sweep algorithm determines all overlaps of a set of + // rectangles in the 2D plane. Our problem maps very well to this + // algorithm and significantly reduces the complexity compared to a + // naive implementation. + // + // Each bounding box of a control point triangle is converted into + // an "entry" event at its smallest X coordinate and an "exit" event + // at its largest X coordinate. Each event has an associated + // one-dimensional interval representing the Y span of the bounding + // box. We sort these events by increasing X coordinate. We then + // iterate through them. For each entry event we add the interval to + // a side interval tree, and query this tree for overlapping + // intervals. Any overlapping interval corresponds to an overlapping + // bounding box. For each exit event we remove the associated + // interval from the interval tree. + + Vector<Segment*> curSegments; + Vector<Segment*> nextSegments; + + // Start things off by considering all of the segments + for (Vector<Contour*>::iterator iter = m_contours.begin(); iter != m_contours.end(); ++iter) { + Contour* cur = *iter; + for (Segment* seg = cur->begin(); seg != cur->end(); seg = seg->next()) { + if (seg->kind() == Segment::Cubic) { + seg->triangulate(LoopBlinnLocalTriangulator::DontComputeInsideEdges, 0); + curSegments.append(seg); + } + } + } + + // Subdivide curves at most this many times + const int MaxIterations = 5; + Vector<SweepInterval> overlaps; + + for (int currentIteration = 0; currentIteration < MaxIterations; ++currentIteration) { + if (!curSegments.size()) + // Done + break; + + Vector<SweepEvent> events; + SweepTree tree(m_arena); + for (Vector<Segment*>::iterator iter = curSegments.begin(); iter != curSegments.end(); ++iter) { + Segment* seg = *iter; + ASSERT(seg->kind() == Segment::Cubic); + for (int i = 0; i < seg->numberOfTriangles(); i++) { + LoopBlinnLocalTriangulator::Triangle* triangle = seg->getTriangle(i); + FloatRect boundingBox; + boundingBox.fitToPoints(triangle->getVertex(0)->xyCoordinates(), + triangle->getVertex(1)->xyCoordinates(), + triangle->getVertex(2)->xyCoordinates()); + // Ignore zero-width triangles to avoid issues with + // coincident entry and exit events for the same triangle + if (boundingBox.maxX() > boundingBox.x()) { + SweepData* data = m_arena->allocateObject<SweepData>(); + data->triangle = triangle; + data->segment = seg; + SweepInterval interval = tree.createInterval(boundingBox.y(), boundingBox.maxY(), data); + // Add entry and exit events + SweepEvent event; + event.setup(boundingBox.x(), true, interval); + events.append(event); + event.setup(boundingBox.maxX(), false, interval); + events.append(event); + } + } + } + + // Sort events by increasing X coordinate + std::sort(events.begin(), events.end()); +#ifndef NDEBUG + for (size_t ii = 1; ii < events.size(); ++ii) + ASSERT(events[ii - 1].x() <= events[ii].x()); +#endif + + // Now iterate through the events + for (Vector<SweepEvent>::iterator iter = events.begin(); iter != events.end(); ++iter) { + SweepEvent event = *iter; + if (event.entry()) { + // See whether the associated segment has been subdivided yet + if (!event.interval().data()->segment->markedForSubdivision()) { + // Query the tree + overlaps.clear(); + tree.allOverlaps(event.interval(), overlaps); + // Now see exactly which triangles overlap this one + for (Vector<SweepInterval>::iterator iter = overlaps.begin(); iter != overlaps.end(); ++iter) { + SweepInterval overlap = *iter; + // Only pay attention to overlaps from a different Segment + if (event.interval().data()->segment != overlap.data()->segment) { + // See whether the triangles actually overlap + if (trianglesOverlap(event.interval().data()->triangle, + overlap.data()->triangle)) { + // Actually subdivide the segments. + // Each one might already have been subdivided. + Segment* seg = event.interval().data()->segment; + conditionallySubdivide(seg, nextSegments); + seg = overlap.data()->segment; + conditionallySubdivide(seg, nextSegments); + } + } + } + } + // Add this interval into the tree + tree.add(event.interval()); + } else { + // Remove this interval from the tree + tree.remove(event.interval()); + } + } + + curSegments.swap(nextSegments); + nextSegments.clear(); + } +} + +void LoopBlinnPathProcessor::conditionallySubdivide(Segment* seg, Vector<Segment*>& nextSegments) +{ + if (!seg->markedForSubdivision()) { + seg->setMarkedForSubdivision(true); + Segment* next = seg->contour()->subdivide(seg); + // Triangulate the newly subdivided segments. + next->triangulate(LoopBlinnLocalTriangulator::DontComputeInsideEdges, 0); + next->next()->triangulate(LoopBlinnLocalTriangulator::DontComputeInsideEdges, 0); + // Add them for the next iteration. + nextSegments.append(next); + nextSegments.append(next->next()); + } +} + +#ifndef NDEBUG +void LoopBlinnPathProcessor::subdivideCurvesSlow() +{ + // Alternate, significantly slower algorithm for curve subdivision + // for use in debugging. + Vector<Segment*> curSegments; + Vector<Segment*> nextSegments; + + // Start things off by considering all of the segments + for (Vector<Contour*>::iterator iter = m_contours.begin(); iter != m_contours.end(); ++iter) { + Contour* cur = *iter; + for (Segment* seg = cur->begin(); seg != cur->end(); seg = seg->next()) { + if (seg->kind() == Segment::Cubic) { + seg->triangulate(LoopBlinnLocalTriangulator::DontComputeInsideEdges, 0); + curSegments.append(seg); + } + } + } + + // Subdivide curves at most this many times + const int MaxIterations = 5; + + for (int currentIteration = 0; currentIteration < MaxIterations; ++currentIteration) { + if (!curSegments.size()) + // Done + break; + + for (Vector<Segment*>::iterator iter = curSegments.begin(); iter != curSegments.end(); ++iter) { + Segment* seg = *iter; + ASSERT(seg->kind() == Segment::Cubic); + for (Vector<Segment*>::iterator iter2 = curSegments.begin(); + iter2 != curSegments.end(); + iter2++) { + Segment* seg2 = *iter2; + ASSERT(seg2->kind() == Segment::Cubic); + if (seg != seg2) { + for (int i = 0; i < seg->numberOfTriangles(); i++) { + LoopBlinnLocalTriangulator::Triangle* triangle = seg->getTriangle(i); + for (int j = 0; j < seg2->numberOfTriangles(); j++) { + LoopBlinnLocalTriangulator::Triangle* triangle2 = seg2->getTriangle(j); + if (trianglesOverlap(triangle, triangle2)) { + conditionallySubdivide(seg, nextSegments); + conditionallySubdivide(seg2, nextSegments); + } + } + } + } + } + } + + curSegments.swap(nextSegments); + nextSegments.clear(); + } +} +#endif + +namespace { + +//---------------------------------------------------------------------- +// Structures and callbacks for tessellation of the interior region of +// the contours. + +// The user data for the GLU tessellator. +struct TessellationState { + TessellationState(LoopBlinnPathCache& inputCache) + : cache(inputCache) { } + + LoopBlinnPathCache& cache; + Vector<void*> allocatedPointers; +}; + +static void vertexCallback(void* vertexData, void* data) +{ + TessellationState* state = static_cast<TessellationState*>(data); + GLdouble* location = static_cast<GLdouble*>(vertexData); + state->cache.addInteriorVertex(static_cast<float>(location[0]), + static_cast<float>(location[1])); +} + +static void combineCallback(GLdouble coords[3], void* vertexData[4], + GLfloat weight[4], void** outData, + void* polygonData) +{ + TessellationState* state = static_cast<TessellationState*>(polygonData); + GLdouble* outVertex = static_cast<GLdouble*>(fastMalloc(3 * sizeof(GLdouble))); + state->allocatedPointers.append(outVertex); + outVertex[0] = coords[0]; + outVertex[1] = coords[1]; + outVertex[2] = coords[2]; + *outData = outVertex; +} + +static void edgeFlagCallback(GLboolean) +{ + // No-op just to prevent triangle strips and fans from being passed to us. + // See the OpenGL Programming Guide, Chapter 11, "Tessellators and Quadrics". +} + +} // anonymous namespace + +void LoopBlinnPathProcessor::tessellateInterior(LoopBlinnPathCache& cache) +{ + // Because the GLU tessellator requires its input in + // double-precision format, we need to make a separate copy of the + // data. + Vector<GLdouble> vertexData; + Vector<size_t> contourEndings; + // For avoiding adding coincident vertices. + float curX = 0, curY = 0; + for (Vector<Contour*>::iterator iter = m_contours.begin(); iter != m_contours.end(); ++iter) { + Contour* cur = *iter; + bool first = true; + for (Segment* seg = cur->begin(); seg != cur->end(); seg = seg->next()) { + int numberOfInteriorVertices = seg->numberOfInteriorVertices(); + for (int i = 0; i < numberOfInteriorVertices - 1; i++) { + FloatPoint point = seg->getInteriorVertex(i); + if (first) { + first = false; + vertexData.append(point.x()); + vertexData.append(point.y()); + vertexData.append(0); + curX = point.x(); + curY = point.y(); + } else if (point.x() != curX || point.y() != curY) { + vertexData.append(point.x()); + vertexData.append(point.y()); + vertexData.append(0); + curX = point.x(); + curY = point.y(); + } + } + } + contourEndings.append(vertexData.size()); + } + // Now that we have all of the vertex data in a stable location in + // memory, call the tessellator. + GLUtesselator* tess = internal_gluNewTess(); + TessellationState state(cache); + internal_gluTessCallback(tess, GLU_TESS_VERTEX_DATA, + reinterpret_cast<GLvoid (*)()>(vertexCallback)); + internal_gluTessCallback(tess, GLU_TESS_COMBINE_DATA, + reinterpret_cast<GLvoid (*)()>(combineCallback)); + internal_gluTessCallback(tess, GLU_TESS_EDGE_FLAG, + reinterpret_cast<GLvoid (*)()>(edgeFlagCallback)); + internal_gluTessBeginPolygon(tess, &state); + internal_gluTessBeginContour(tess); + GLdouble* base = vertexData.data(); + int contourIndex = 0; + for (size_t i = 0; i < vertexData.size(); i += 3) { + if (i == contourEndings[contourIndex]) { + internal_gluTessEndContour(tess); + internal_gluTessBeginContour(tess); + ++contourIndex; + } + internal_gluTessVertex(tess, &base[i], &base[i]); + } + internal_gluTessEndContour(tess); + internal_gluTessEndPolygon(tess); + for (size_t i = 0; i < state.allocatedPointers.size(); i++) + fastFree(state.allocatedPointers[i]); + internal_gluDeleteTess(tess); +} + +} // namespace WebCore |