GrAAConvexPathRenderer.cpp revision 5d01bec07a0740b30e4ebc51eec9057009a09bc2
1
2/*
3 * Copyright 2012 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9#include "GrAAConvexPathRenderer.h"
10
11#include "GrContext.h"
12#include "GrDrawState.h"
13#include "GrDrawTargetCaps.h"
14#include "GrEffect.h"
15#include "GrPathUtils.h"
16#include "GrTBackendEffectFactory.h"
17#include "SkString.h"
18#include "SkStrokeRec.h"
19#include "SkTrace.h"
20
21#include "gl/GrGLEffect.h"
22#include "gl/GrGLSL.h"
23
24GrAAConvexPathRenderer::GrAAConvexPathRenderer() {
25}
26
27namespace {
28
29struct Segment {
30    enum {
31        // These enum values are assumed in member functions below.
32        kLine = 0,
33        kQuad = 1,
34    } fType;
35
36    // line uses one pt, quad uses 2 pts
37    GrPoint fPts[2];
38    // normal to edge ending at each pt
39    GrVec fNorms[2];
40    // is the corner where the previous segment meets this segment
41    // sharp. If so, fMid is a normalized bisector facing outward.
42    GrVec fMid;
43
44    int countPoints() {
45        GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
46        return fType + 1;
47    }
48    const SkPoint& endPt() const {
49        GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
50        return fPts[fType];
51    };
52    const SkPoint& endNorm() const {
53        GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
54        return fNorms[fType];
55    };
56};
57
58typedef SkTArray<Segment, true> SegmentArray;
59
60void center_of_mass(const SegmentArray& segments, SkPoint* c) {
61    SkScalar area = 0;
62    SkPoint center = {0, 0};
63    int count = segments.count();
64    SkPoint p0 = {0, 0};
65    if (count > 2) {
66        // We translate the polygon so that the first point is at the origin.
67        // This avoids some precision issues with small area polygons far away
68        // from the origin.
69        p0 = segments[0].endPt();
70        SkPoint pi;
71        SkPoint pj;
72        // the first and last iteration of the below loop would compute
73        // zeros since the starting / ending point is (0,0). So instead we start
74        // at i=1 and make the last iteration i=count-2.
75        pj = segments[1].endPt() - p0;
76        for (int i = 1; i < count - 1; ++i) {
77            pi = pj;
78            const SkPoint pj = segments[i + 1].endPt() - p0;
79
80            SkScalar t = SkScalarMul(pi.fX, pj.fY) - SkScalarMul(pj.fX, pi.fY);
81            area += t;
82            center.fX += (pi.fX + pj.fX) * t;
83            center.fY += (pi.fY + pj.fY) * t;
84
85        }
86    }
87    // If the poly has no area then we instead return the average of
88    // its points.
89    if (SkScalarNearlyZero(area)) {
90        SkPoint avg;
91        avg.set(0, 0);
92        for (int i = 0; i < count; ++i) {
93            const SkPoint& pt = segments[i].endPt();
94            avg.fX += pt.fX;
95            avg.fY += pt.fY;
96        }
97        SkScalar denom = SK_Scalar1 / count;
98        avg.scale(denom);
99        *c = avg;
100    } else {
101        area *= 3;
102        area = SkScalarDiv(SK_Scalar1, area);
103        center.fX = SkScalarMul(center.fX, area);
104        center.fY = SkScalarMul(center.fY, area);
105        // undo the translate of p0 to the origin.
106        *c = center + p0;
107    }
108    GrAssert(!SkScalarIsNaN(c->fX) && !SkScalarIsNaN(c->fY));
109}
110
111void compute_vectors(SegmentArray* segments,
112                     SkPoint* fanPt,
113                     SkPath::Direction dir,
114                     int* vCount,
115                     int* iCount) {
116    center_of_mass(*segments, fanPt);
117    int count = segments->count();
118
119    // Make the normals point towards the outside
120    GrPoint::Side normSide;
121    if (dir == SkPath::kCCW_Direction) {
122        normSide = GrPoint::kRight_Side;
123    } else {
124        normSide = GrPoint::kLeft_Side;
125    }
126
127    *vCount = 0;
128    *iCount = 0;
129    // compute normals at all points
130    for (int a = 0; a < count; ++a) {
131        const Segment& sega = (*segments)[a];
132        int b = (a + 1) % count;
133        Segment& segb = (*segments)[b];
134
135        const GrPoint* prevPt = &sega.endPt();
136        int n = segb.countPoints();
137        for (int p = 0; p < n; ++p) {
138            segb.fNorms[p] = segb.fPts[p] - *prevPt;
139            segb.fNorms[p].normalize();
140            segb.fNorms[p].setOrthog(segb.fNorms[p], normSide);
141            prevPt = &segb.fPts[p];
142        }
143        if (Segment::kLine == segb.fType) {
144            *vCount += 5;
145            *iCount += 9;
146        } else {
147            *vCount += 6;
148            *iCount += 12;
149        }
150    }
151
152    // compute mid-vectors where segments meet. TODO: Detect shallow corners
153    // and leave out the wedges and close gaps by stitching segments together.
154    for (int a = 0; a < count; ++a) {
155        const Segment& sega = (*segments)[a];
156        int b = (a + 1) % count;
157        Segment& segb = (*segments)[b];
158        segb.fMid = segb.fNorms[0] + sega.endNorm();
159        segb.fMid.normalize();
160        // corner wedges
161        *vCount += 4;
162        *iCount += 6;
163    }
164}
165
166struct DegenerateTestData {
167    DegenerateTestData() { fStage = kInitial; }
168    bool isDegenerate() const { return kNonDegenerate != fStage; }
169    enum {
170        kInitial,
171        kPoint,
172        kLine,
173        kNonDegenerate
174    }           fStage;
175    GrPoint     fFirstPoint;
176    GrVec       fLineNormal;
177    SkScalar    fLineC;
178};
179
180void update_degenerate_test(DegenerateTestData* data, const GrPoint& pt) {
181    static const SkScalar TOL = (SK_Scalar1 / 16);
182    static const SkScalar TOL_SQD = SkScalarMul(TOL, TOL);
183
184    switch (data->fStage) {
185        case DegenerateTestData::kInitial:
186            data->fFirstPoint = pt;
187            data->fStage = DegenerateTestData::kPoint;
188            break;
189        case DegenerateTestData::kPoint:
190            if (pt.distanceToSqd(data->fFirstPoint) > TOL_SQD) {
191                data->fLineNormal = pt - data->fFirstPoint;
192                data->fLineNormal.normalize();
193                data->fLineNormal.setOrthog(data->fLineNormal);
194                data->fLineC = -data->fLineNormal.dot(data->fFirstPoint);
195                data->fStage = DegenerateTestData::kLine;
196            }
197            break;
198        case DegenerateTestData::kLine:
199            if (SkScalarAbs(data->fLineNormal.dot(pt) + data->fLineC) > TOL) {
200                data->fStage = DegenerateTestData::kNonDegenerate;
201            }
202        case DegenerateTestData::kNonDegenerate:
203            break;
204        default:
205            GrCrash("Unexpected degenerate test stage.");
206    }
207}
208
209inline bool get_direction(const SkPath& path, const SkMatrix& m, SkPath::Direction* dir) {
210    if (!path.cheapComputeDirection(dir)) {
211        return false;
212    }
213    // check whether m reverses the orientation
214    GrAssert(!m.hasPerspective());
215    SkScalar det2x2 = SkScalarMul(m.get(SkMatrix::kMScaleX), m.get(SkMatrix::kMScaleY)) -
216                      SkScalarMul(m.get(SkMatrix::kMSkewX), m.get(SkMatrix::kMSkewY));
217    if (det2x2 < 0) {
218        *dir = SkPath::OppositeDirection(*dir);
219    }
220    return true;
221}
222
223bool get_segments(const SkPath& path,
224                  const SkMatrix& m,
225                  SegmentArray* segments,
226                  SkPoint* fanPt,
227                  int* vCount,
228                  int* iCount) {
229    SkPath::Iter iter(path, true);
230    // This renderer over-emphasizes very thin path regions. We use the distance
231    // to the path from the sample to compute coverage. Every pixel intersected
232    // by the path will be hit and the maximum distance is sqrt(2)/2. We don't
233    // notice that the sample may be close to a very thin area of the path and
234    // thus should be very light. This is particularly egregious for degenerate
235    // line paths. We detect paths that are very close to a line (zero area) and
236    // draw nothing.
237    DegenerateTestData degenerateData;
238    SkPath::Direction dir;
239    // get_direction can fail for some degenerate paths.
240    if (!get_direction(path, m, &dir)) {
241        return false;
242    }
243
244    for (;;) {
245        GrPoint pts[4];
246        GrPathCmd cmd = (GrPathCmd)iter.next(pts);
247        switch (cmd) {
248            case kMove_PathCmd:
249                m.mapPoints(pts, 1);
250                update_degenerate_test(&degenerateData, pts[0]);
251                break;
252            case kLine_PathCmd: {
253                m.mapPoints(pts + 1, 1);
254                update_degenerate_test(&degenerateData, pts[1]);
255                segments->push_back();
256                segments->back().fType = Segment::kLine;
257                segments->back().fPts[0] = pts[1];
258                break;
259            }
260            case kQuadratic_PathCmd:
261                m.mapPoints(pts + 1, 2);
262                update_degenerate_test(&degenerateData, pts[1]);
263                update_degenerate_test(&degenerateData, pts[2]);
264                segments->push_back();
265                segments->back().fType = Segment::kQuad;
266                segments->back().fPts[0] = pts[1];
267                segments->back().fPts[1] = pts[2];
268                break;
269            case kCubic_PathCmd: {
270                m.mapPoints(pts, 4);
271                update_degenerate_test(&degenerateData, pts[1]);
272                update_degenerate_test(&degenerateData, pts[2]);
273                update_degenerate_test(&degenerateData, pts[3]);
274                // unlike quads and lines, the pts[0] will also be read (in
275                // convertCubicToQuads).
276                SkSTArray<15, SkPoint, true> quads;
277                GrPathUtils::convertCubicToQuads(pts, SK_Scalar1, true, dir, &quads);
278                int count = quads.count();
279                for (int q = 0; q < count; q += 3) {
280                    segments->push_back();
281                    segments->back().fType = Segment::kQuad;
282                    segments->back().fPts[0] = quads[q + 1];
283                    segments->back().fPts[1] = quads[q + 2];
284                }
285                break;
286            };
287            case kEnd_PathCmd:
288                if (degenerateData.isDegenerate()) {
289                    return false;
290                } else {
291                    compute_vectors(segments, fanPt, dir, vCount, iCount);
292                    return true;
293                }
294            default:
295                break;
296        }
297    }
298}
299
300struct QuadVertex {
301    GrPoint  fPos;
302    GrPoint  fUV;
303    SkScalar fD0;
304    SkScalar fD1;
305};
306
307void create_vertices(const SegmentArray&  segments,
308                     const SkPoint& fanPt,
309                     QuadVertex*    verts,
310                     uint16_t*      idxs) {
311    int v = 0;
312    int i = 0;
313
314    int count = segments.count();
315    for (int a = 0; a < count; ++a) {
316        const Segment& sega = segments[a];
317        int b = (a + 1) % count;
318        const Segment& segb = segments[b];
319
320        // FIXME: These tris are inset in the 1 unit arc around the corner
321        verts[v + 0].fPos = sega.endPt();
322        verts[v + 1].fPos = verts[v + 0].fPos + sega.endNorm();
323        verts[v + 2].fPos = verts[v + 0].fPos + segb.fMid;
324        verts[v + 3].fPos = verts[v + 0].fPos + segb.fNorms[0];
325        verts[v + 0].fUV.set(0,0);
326        verts[v + 1].fUV.set(0,-SK_Scalar1);
327        verts[v + 2].fUV.set(0,-SK_Scalar1);
328        verts[v + 3].fUV.set(0,-SK_Scalar1);
329        verts[v + 0].fD0 = verts[v + 0].fD1 = -SK_Scalar1;
330        verts[v + 1].fD0 = verts[v + 1].fD1 = -SK_Scalar1;
331        verts[v + 2].fD0 = verts[v + 2].fD1 = -SK_Scalar1;
332        verts[v + 3].fD0 = verts[v + 3].fD1 = -SK_Scalar1;
333
334        idxs[i + 0] = v + 0;
335        idxs[i + 1] = v + 2;
336        idxs[i + 2] = v + 1;
337        idxs[i + 3] = v + 0;
338        idxs[i + 4] = v + 3;
339        idxs[i + 5] = v + 2;
340
341        v += 4;
342        i += 6;
343
344        if (Segment::kLine == segb.fType) {
345            verts[v + 0].fPos = fanPt;
346            verts[v + 1].fPos = sega.endPt();
347            verts[v + 2].fPos = segb.fPts[0];
348
349            verts[v + 3].fPos = verts[v + 1].fPos + segb.fNorms[0];
350            verts[v + 4].fPos = verts[v + 2].fPos + segb.fNorms[0];
351
352            // we draw the line edge as a degenerate quad (u is 0, v is the
353            // signed distance to the edge)
354            SkScalar dist = fanPt.distanceToLineBetween(verts[v + 1].fPos,
355                                                        verts[v + 2].fPos);
356            verts[v + 0].fUV.set(0, dist);
357            verts[v + 1].fUV.set(0, 0);
358            verts[v + 2].fUV.set(0, 0);
359            verts[v + 3].fUV.set(0, -SK_Scalar1);
360            verts[v + 4].fUV.set(0, -SK_Scalar1);
361
362            verts[v + 0].fD0 = verts[v + 0].fD1 = -SK_Scalar1;
363            verts[v + 1].fD0 = verts[v + 1].fD1 = -SK_Scalar1;
364            verts[v + 2].fD0 = verts[v + 2].fD1 = -SK_Scalar1;
365            verts[v + 3].fD0 = verts[v + 3].fD1 = -SK_Scalar1;
366            verts[v + 4].fD0 = verts[v + 4].fD1 = -SK_Scalar1;
367
368            idxs[i + 0] = v + 0;
369            idxs[i + 1] = v + 2;
370            idxs[i + 2] = v + 1;
371
372            idxs[i + 3] = v + 3;
373            idxs[i + 4] = v + 1;
374            idxs[i + 5] = v + 2;
375
376            idxs[i + 6] = v + 4;
377            idxs[i + 7] = v + 3;
378            idxs[i + 8] = v + 2;
379
380            v += 5;
381            i += 9;
382        } else {
383            GrPoint qpts[] = {sega.endPt(), segb.fPts[0], segb.fPts[1]};
384
385            GrVec midVec = segb.fNorms[0] + segb.fNorms[1];
386            midVec.normalize();
387
388            verts[v + 0].fPos = fanPt;
389            verts[v + 1].fPos = qpts[0];
390            verts[v + 2].fPos = qpts[2];
391            verts[v + 3].fPos = qpts[0] + segb.fNorms[0];
392            verts[v + 4].fPos = qpts[2] + segb.fNorms[1];
393            verts[v + 5].fPos = qpts[1] + midVec;
394
395            SkScalar c = segb.fNorms[0].dot(qpts[0]);
396            verts[v + 0].fD0 =  -segb.fNorms[0].dot(fanPt) + c;
397            verts[v + 1].fD0 =  0.f;
398            verts[v + 2].fD0 =  -segb.fNorms[0].dot(qpts[2]) + c;
399            verts[v + 3].fD0 = -SK_ScalarMax/100;
400            verts[v + 4].fD0 = -SK_ScalarMax/100;
401            verts[v + 5].fD0 = -SK_ScalarMax/100;
402
403            c = segb.fNorms[1].dot(qpts[2]);
404            verts[v + 0].fD1 =  -segb.fNorms[1].dot(fanPt) + c;
405            verts[v + 1].fD1 =  -segb.fNorms[1].dot(qpts[0]) + c;
406            verts[v + 2].fD1 =  0.f;
407            verts[v + 3].fD1 = -SK_ScalarMax/100;
408            verts[v + 4].fD1 = -SK_ScalarMax/100;
409            verts[v + 5].fD1 = -SK_ScalarMax/100;
410
411            GrPathUtils::QuadUVMatrix toUV(qpts);
412            toUV.apply<6, sizeof(QuadVertex), sizeof(GrPoint)>(verts + v);
413
414            idxs[i + 0] = v + 3;
415            idxs[i + 1] = v + 1;
416            idxs[i + 2] = v + 2;
417            idxs[i + 3] = v + 4;
418            idxs[i + 4] = v + 3;
419            idxs[i + 5] = v + 2;
420
421            idxs[i + 6] = v + 5;
422            idxs[i + 7] = v + 3;
423            idxs[i + 8] = v + 4;
424
425            idxs[i +  9] = v + 0;
426            idxs[i + 10] = v + 2;
427            idxs[i + 11] = v + 1;
428
429            v += 6;
430            i += 12;
431        }
432    }
433}
434
435}
436
437///////////////////////////////////////////////////////////////////////////////
438
439/*
440 * Quadratic specified by 0=u^2-v canonical coords. u and v are the first
441 * two components of the vertex attribute. Coverage is based on signed
442 * distance with negative being inside, positive outside. The edge is specified in
443 * window space (y-down). If either the third or fourth component of the interpolated
444 * vertex coord is > 0 then the pixel is considered outside the edge. This is used to
445 * attempt to trim to a portion of the infinite quad.
446 * Requires shader derivative instruction support.
447 */
448
449class QuadEdgeEffect : public GrEffect {
450public:
451
452    static GrEffectRef* Create() {
453        // we go through this so we only have one copy of each effect
454        static SkAutoTUnref<GrEffectRef> gQuadEdgeEffectRef(
455                    CreateEffectRef(AutoEffectUnref(SkNEW(QuadEdgeEffect))));
456
457        gQuadEdgeEffectRef.get()->ref();
458        return gQuadEdgeEffectRef;
459    }
460
461    virtual ~QuadEdgeEffect() {}
462
463    static const char* Name() { return "QuadEdge"; }
464
465    virtual void getConstantColorComponents(GrColor* color,
466                                            uint32_t* validFlags) const SK_OVERRIDE {
467        *validFlags = 0;
468    }
469
470    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE {
471        return GrTBackendEffectFactory<QuadEdgeEffect>::getInstance();
472    }
473
474    class GLEffect : public GrGLEffect {
475    public:
476        GLEffect(const GrBackendEffectFactory& factory, const GrDrawEffect&)
477            : INHERITED (factory) {}
478
479        virtual void emitCode(GrGLShaderBuilder* builder,
480                              const GrDrawEffect& drawEffect,
481                              EffectKey key,
482                              const char* outputColor,
483                              const char* inputColor,
484                              const TextureSamplerArray& samplers) SK_OVERRIDE {
485            const char *vsName, *fsName;
486            const SkString* attrName =
487                builder->getEffectAttributeName(drawEffect.getVertexAttribIndices()[0]);
488            builder->fsCodeAppendf("\t\tfloat edgeAlpha;\n");
489
490            SkAssertResult(builder->enableFeature(
491                                              GrGLShaderBuilder::kStandardDerivatives_GLSLFeature));
492            builder->addVarying(kVec4f_GrSLType, "QuadEdge", &vsName, &fsName);
493
494            // keep the derivative instructions outside the conditional
495            builder->fsCodeAppendf("\t\tvec2 duvdx = dFdx(%s.xy);\n", fsName);
496            builder->fsCodeAppendf("\t\tvec2 duvdy = dFdy(%s.xy);\n", fsName);
497            builder->fsCodeAppendf("\t\tif (%s.z > 0.0 && %s.w > 0.0) {\n", fsName, fsName);
498            // today we know z and w are in device space. We could use derivatives
499            builder->fsCodeAppendf("\t\t\tedgeAlpha = min(min(%s.z, %s.w) + 0.5, 1.0);\n", fsName,
500                                    fsName);
501            builder->fsCodeAppendf ("\t\t} else {\n");
502            builder->fsCodeAppendf("\t\t\tvec2 gF = vec2(2.0*%s.x*duvdx.x - duvdx.y,\n"
503                                   "\t\t\t               2.0*%s.x*duvdy.x - duvdy.y);\n",
504                                   fsName, fsName);
505            builder->fsCodeAppendf("\t\t\tedgeAlpha = (%s.x*%s.x - %s.y);\n", fsName, fsName,
506                                    fsName);
507            builder->fsCodeAppendf("\t\t\tedgeAlpha = "
508                                   "clamp(0.5 - edgeAlpha / length(gF), 0.0, 1.0);\n\t\t}\n");
509
510            SkString modulate;
511            GrGLSLModulate4f(&modulate, inputColor, "edgeAlpha");
512            builder->fsCodeAppendf("\t%s = %s;\n", outputColor, modulate.c_str());
513
514            builder->vsCodeAppendf("\t%s = %s;\n", vsName, attrName->c_str());
515        }
516
517        static inline EffectKey GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
518            return 0x0;
519        }
520
521        virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE {}
522
523    private:
524        typedef GrGLEffect INHERITED;
525    };
526
527private:
528    QuadEdgeEffect() {
529        this->addVertexAttrib(kVec4f_GrSLType);
530    }
531
532    virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
533        return true;
534    }
535
536    GR_DECLARE_EFFECT_TEST;
537
538    typedef GrEffect INHERITED;
539};
540
541GR_DEFINE_EFFECT_TEST(QuadEdgeEffect);
542
543GrEffectRef* QuadEdgeEffect::TestCreate(SkMWCRandom* random,
544                                        GrContext*,
545                                        const GrDrawTargetCaps& caps,
546                                        GrTexture*[]) {
547    // Doesn't work without derivative instructions.
548    return caps.shaderDerivativeSupport() ? QuadEdgeEffect::Create() : NULL;
549}
550
551///////////////////////////////////////////////////////////////////////////////
552
553bool GrAAConvexPathRenderer::canDrawPath(const SkPath& path,
554                                         const SkStrokeRec& stroke,
555                                         const GrDrawTarget* target,
556                                         bool antiAlias) const {
557    return (target->caps()->shaderDerivativeSupport() && antiAlias &&
558            stroke.isFillStyle() && !path.isInverseFillType() && path.isConvex());
559}
560
561bool GrAAConvexPathRenderer::onDrawPath(const SkPath& origPath,
562                                        const SkStrokeRec&,
563                                        GrDrawTarget* target,
564                                        bool antiAlias) {
565
566    const SkPath* path = &origPath;
567    if (path->isEmpty()) {
568        return true;
569    }
570
571    GrDrawTarget::AutoStateRestore asr(target, GrDrawTarget::kPreserve_ASRInit);
572    GrDrawState* drawState = target->drawState();
573
574    GrDrawState::AutoDeviceCoordDraw adcd(drawState);
575    if (!adcd.succeeded()) {
576        return false;
577    }
578    const SkMatrix* vm = &adcd.getOriginalMatrix();
579
580    // We use the fact that SkPath::transform path does subdivision based on
581    // perspective. Otherwise, we apply the view matrix when copying to the
582    // segment representation.
583    SkPath tmpPath;
584    if (vm->hasPerspective()) {
585        origPath.transform(*vm, &tmpPath);
586        path = &tmpPath;
587        vm = &SkMatrix::I();
588    }
589
590    QuadVertex *verts;
591    uint16_t* idxs;
592
593    int vCount;
594    int iCount;
595    enum {
596        kPreallocSegmentCnt = 512 / sizeof(Segment),
597    };
598    SkSTArray<kPreallocSegmentCnt, Segment, true> segments;
599    SkPoint fanPt;
600
601    if (!get_segments(*path, *vm, &segments, &fanPt, &vCount, &iCount)) {
602        return false;
603    }
604
605    // position + edge
606    static const GrVertexAttrib kAttribs[] = {
607        {kVec2f_GrVertexAttribType, 0,               kPosition_GrVertexAttribBinding},
608        {kVec4f_GrVertexAttribType, sizeof(GrPoint), kEffect_GrVertexAttribBinding}
609    };
610    drawState->setVertexAttribs(kAttribs, SK_ARRAY_COUNT(kAttribs));
611
612    enum {
613        // the edge effects share this stage with glyph rendering
614        // (kGlyphMaskStage in GrTextContext) && SW path rendering
615        // (kPathMaskStage in GrSWMaskHelper)
616        kEdgeEffectStage = GrPaint::kTotalStages,
617    };
618    static const int kEdgeAttrIndex = 1;
619    GrEffectRef* quadEffect = QuadEdgeEffect::Create();
620    drawState->setEffect(kEdgeEffectStage, quadEffect, kEdgeAttrIndex)->unref();
621
622    GrDrawTarget::AutoReleaseGeometry arg(target, vCount, iCount);
623    if (!arg.succeeded()) {
624        return false;
625    }
626    GrAssert(sizeof(QuadVertex) == drawState->getVertexSize());
627    verts = reinterpret_cast<QuadVertex*>(arg.vertices());
628    idxs = reinterpret_cast<uint16_t*>(arg.indices());
629
630    create_vertices(segments, fanPt, verts, idxs);
631
632    target->drawIndexed(kTriangles_GrPrimitiveType,
633                        0,        // start vertex
634                        0,        // start index
635                        vCount,
636                        iCount);
637
638    return true;
639}
640