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/*
* 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.
*/
// The main entry point for Loop and Blinn's GPU accelerated curve
// rendering algorithm.
#ifndef LoopBlinnPathProcessor_h
#define LoopBlinnPathProcessor_h
#include <wtf/Noncopyable.h>
#include <wtf/PassRefPtr.h>
#include <wtf/RefPtr.h>
#include <wtf/Vector.h>
namespace WebCore {
// We use a namespace for classes which are simply implementation
// details of the algorithm but which we need to reference from the
// class definition.
namespace LoopBlinnPathProcessorImplementation {
class Contour;
class Segment;
} // namespace LoopBlinnPathProcessorImplementation
class Path;
class LoopBlinnPathCache;
class PODArena;
// The LoopBlinnPathProcessor turns a Path (assumed to contain one or
// more closed regions) into a set of exterior and interior triangles,
// stored in the LoopBlinnPathCache. The exterior triangles have
// associated 3D texture coordinates which are used to evaluate the
// curve's inside/outside function on a per-pixel basis. The interior
// triangles are filled with 100% opacity.
//
// Note that the fill style and management of multiple layers are
// separate concerns, handled at a higher level with shaders and
// polygon offsets.
class LoopBlinnPathProcessor {
public:
LoopBlinnPathProcessor();
explicit LoopBlinnPathProcessor(PassRefPtr<PODArena>);
~LoopBlinnPathProcessor();
// Transforms the given path into a triangle mesh for rendering
// using Loop and Blinn's shader, placing the result into the given
// LoopBlinnPathCache.
void process(const Path&, LoopBlinnPathCache&);
#ifndef NDEBUG
// Enables or disables verbose logging in debug mode.
void setVerboseLogging(bool onOrOff);
#endif
private:
// Builds a list of contours for the given path.
void buildContours(const Path&);
// Determines whether the left or right side of each contour should
// be filled.
void determineSidesToFill();
// Determines whether the given (closed) contour is oriented
// clockwise or counterclockwise.
void determineOrientation(LoopBlinnPathProcessorImplementation::Contour*);
// Subdivides the curves so that there are no overlaps of the
// triangles associated with the curves' control points.
void subdivideCurves();
// Helper function used during curve subdivision.
void conditionallySubdivide(LoopBlinnPathProcessorImplementation::Segment*,
Vector<LoopBlinnPathProcessorImplementation::Segment*>& nextSegments);
// Tessellates the interior regions of the contours.
void tessellateInterior(LoopBlinnPathCache&);
#ifndef NDEBUG
// For debugging the orientation computation. Returns all of the
// segments overlapping the given Y coordinate.
Vector<LoopBlinnPathProcessorImplementation::Segment*> allSegmentsOverlappingY(LoopBlinnPathProcessorImplementation::Contour*, float x, float y);
// For debugging the curve subdivision algorithm. Subdivides the
// curves using an alternate, slow (O(n^3)) algorithm.
void subdivideCurvesSlow();
#endif
// PODArena from which to allocate temporary objects.
RefPtr<PODArena> m_arena;
// The contours described by the path.
Vector<LoopBlinnPathProcessorImplementation::Contour*> m_contours;
#ifndef NDEBUG
// Whether or not to perform verbose logging in debug mode.
bool m_verboseLogging;
#endif
};
} // namespace WebCore
#endif // LoopBlinnPathProcessor_h
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