1/*
2 * Copyright 2014 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "GrConvexPolyEffect.h"
9
10#include "gl/GrGLEffect.h"
11#include "gl/GrGLSL.h"
12#include "GrTBackendEffectFactory.h"
13
14#include "SkPath.h"
15
16//////////////////////////////////////////////////////////////////////////////
17class GLAARectEffect;
18
19class AARectEffect : public GrEffect {
20public:
21    typedef GLAARectEffect GLEffect;
22
23    const SkRect& getRect() const { return fRect; }
24
25    static const char* Name() { return "AARect"; }
26
27    static GrEffectRef* Create(GrEffectEdgeType edgeType, const SkRect& rect) {
28        return CreateEffectRef(AutoEffectUnref(SkNEW_ARGS(AARectEffect, (edgeType, rect))));
29    }
30
31    virtual void getConstantColorComponents(GrColor* color,
32                                            uint32_t* validFlags) const SK_OVERRIDE {
33        if (fRect.isEmpty()) {
34            // An empty rect will have no coverage anywhere.
35            *color = 0x00000000;
36            *validFlags = kRGBA_GrColorComponentFlags;
37        } else {
38            *validFlags = 0;
39        }
40    }
41
42    GrEffectEdgeType getEdgeType() const { return fEdgeType; }
43
44    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
45
46private:
47    AARectEffect(GrEffectEdgeType edgeType, const SkRect& rect) : fRect(rect), fEdgeType(edgeType) {
48        this->setWillReadFragmentPosition();
49    }
50
51    virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
52        const AARectEffect& aare = CastEffect<AARectEffect>(other);
53        return fRect == aare.fRect;
54    }
55
56    SkRect fRect;
57    GrEffectEdgeType fEdgeType;
58
59    typedef GrEffect INHERITED;
60
61    GR_DECLARE_EFFECT_TEST;
62
63};
64
65GR_DEFINE_EFFECT_TEST(AARectEffect);
66
67GrEffectRef* AARectEffect::TestCreate(SkRandom* random,
68                                      GrContext*,
69                                      const GrDrawTargetCaps& caps,
70                                      GrTexture*[]) {
71    SkRect rect = SkRect::MakeLTRB(random->nextSScalar1(),
72                                   random->nextSScalar1(),
73                                   random->nextSScalar1(),
74                                   random->nextSScalar1());
75    GrEffectRef* effect;
76    do {
77        GrEffectEdgeType edgeType = static_cast<GrEffectEdgeType>(random->nextULessThan(
78                                                                    kGrEffectEdgeTypeCnt));
79
80        effect = AARectEffect::Create(edgeType, rect);
81    } while (NULL == effect);
82    return effect;
83}
84
85//////////////////////////////////////////////////////////////////////////////
86
87class GLAARectEffect : public GrGLEffect {
88public:
89    GLAARectEffect(const GrBackendEffectFactory&, const GrDrawEffect&);
90
91    virtual void emitCode(GrGLShaderBuilder* builder,
92                          const GrDrawEffect& drawEffect,
93                          EffectKey key,
94                          const char* outputColor,
95                          const char* inputColor,
96                          const TransformedCoordsArray&,
97                          const TextureSamplerArray&) SK_OVERRIDE;
98
99    static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);
100
101    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
102
103private:
104    GrGLUniformManager::UniformHandle   fRectUniform;
105    SkRect                              fPrevRect;
106    typedef GrGLEffect INHERITED;
107};
108
109GLAARectEffect::GLAARectEffect(const GrBackendEffectFactory& factory,
110                               const GrDrawEffect& drawEffect)
111    : INHERITED (factory) {
112    fPrevRect.fLeft = SK_ScalarNaN;
113}
114
115void GLAARectEffect::emitCode(GrGLShaderBuilder* builder,
116                              const GrDrawEffect& drawEffect,
117                              EffectKey key,
118                              const char* outputColor,
119                              const char* inputColor,
120                              const TransformedCoordsArray&,
121                              const TextureSamplerArray& samplers) {
122    const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
123    const char *rectName;
124    // The rect uniform's xyzw refer to (left + 0.5, top + 0.5, right - 0.5, bottom - 0.5),
125    // respectively.
126    fRectUniform = builder->addUniform(GrGLShaderBuilder::kFragment_Visibility,
127                                       kVec4f_GrSLType,
128                                       "rect",
129                                       &rectName);
130    const char* fragmentPos = builder->fragmentPosition();
131    if (GrEffectEdgeTypeIsAA(aare.getEdgeType())) {
132        // The amount of coverage removed in x and y by the edges is computed as a pair of negative
133        // numbers, xSub and ySub.
134        builder->fsCodeAppend("\t\tfloat xSub, ySub;\n");
135        builder->fsCodeAppendf("\t\txSub = min(%s.x - %s.x, 0.0);\n", fragmentPos, rectName);
136        builder->fsCodeAppendf("\t\txSub += min(%s.z - %s.x, 0.0);\n", rectName, fragmentPos);
137        builder->fsCodeAppendf("\t\tySub = min(%s.y - %s.y, 0.0);\n", fragmentPos, rectName);
138        builder->fsCodeAppendf("\t\tySub += min(%s.w - %s.y, 0.0);\n", rectName, fragmentPos);
139        // Now compute coverage in x and y and multiply them to get the fraction of the pixel
140        // covered.
141        builder->fsCodeAppendf("\t\tfloat alpha = (1.0 + max(xSub, -1.0)) * (1.0 + max(ySub, -1.0));\n");
142    } else {
143        builder->fsCodeAppendf("\t\tfloat alpha = 1.0;\n");
144        builder->fsCodeAppendf("\t\talpha *= (%s.x - %s.x) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
145        builder->fsCodeAppendf("\t\talpha *= (%s.z - %s.x) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
146        builder->fsCodeAppendf("\t\talpha *= (%s.y - %s.y) > -0.5 ? 1.0 : 0.0;\n", fragmentPos, rectName);
147        builder->fsCodeAppendf("\t\talpha *= (%s.w - %s.y) > -0.5 ? 1.0 : 0.0;\n", rectName, fragmentPos);
148    }
149
150    if (GrEffectEdgeTypeIsInverseFill(aare.getEdgeType())) {
151        builder->fsCodeAppend("\t\talpha = 1.0 - alpha;\n");
152    }
153    builder->fsCodeAppendf("\t\t%s = %s;\n", outputColor,
154                           (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
155}
156
157void GLAARectEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
158    const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
159    const SkRect& rect = aare.getRect();
160    if (rect != fPrevRect) {
161        uman.set4f(fRectUniform, rect.fLeft + 0.5f, rect.fTop + 0.5f,
162                   rect.fRight - 0.5f, rect.fBottom - 0.5f);
163        fPrevRect = rect;
164    }
165}
166
167GrGLEffect::EffectKey GLAARectEffect::GenKey(const GrDrawEffect& drawEffect, const GrGLCaps&) {
168    const AARectEffect& aare = drawEffect.castEffect<AARectEffect>();
169    return aare.getEdgeType();
170}
171
172const GrBackendEffectFactory& AARectEffect::getFactory() const {
173    return GrTBackendEffectFactory<AARectEffect>::getInstance();
174}
175
176//////////////////////////////////////////////////////////////////////////////
177
178class GrGLConvexPolyEffect : public GrGLEffect {
179public:
180    GrGLConvexPolyEffect(const GrBackendEffectFactory&, const GrDrawEffect&);
181
182    virtual void emitCode(GrGLShaderBuilder* builder,
183                          const GrDrawEffect& drawEffect,
184                          EffectKey key,
185                          const char* outputColor,
186                          const char* inputColor,
187                          const TransformedCoordsArray&,
188                          const TextureSamplerArray&) SK_OVERRIDE;
189
190    static inline EffectKey GenKey(const GrDrawEffect&, const GrGLCaps&);
191
192    virtual void setData(const GrGLUniformManager&, const GrDrawEffect&) SK_OVERRIDE;
193
194private:
195    GrGLUniformManager::UniformHandle   fEdgeUniform;
196    SkScalar                            fPrevEdges[3 * GrConvexPolyEffect::kMaxEdges];
197    typedef GrGLEffect INHERITED;
198};
199
200GrGLConvexPolyEffect::GrGLConvexPolyEffect(const GrBackendEffectFactory& factory,
201                                           const GrDrawEffect& drawEffect)
202    : INHERITED (factory) {
203    fPrevEdges[0] = SK_ScalarNaN;
204}
205
206void GrGLConvexPolyEffect::emitCode(GrGLShaderBuilder* builder,
207                                    const GrDrawEffect& drawEffect,
208                                    EffectKey key,
209                                    const char* outputColor,
210                                    const char* inputColor,
211                                    const TransformedCoordsArray&,
212                                    const TextureSamplerArray& samplers) {
213    const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
214
215    const char *edgeArrayName;
216    fEdgeUniform = builder->addUniformArray(GrGLShaderBuilder::kFragment_Visibility,
217                                            kVec3f_GrSLType,
218                                            "edges",
219                                            cpe.getEdgeCount(),
220                                            &edgeArrayName);
221    builder->fsCodeAppend("\t\tfloat alpha = 1.0;\n");
222    builder->fsCodeAppend("\t\tfloat edge;\n");
223    const char* fragmentPos = builder->fragmentPosition();
224    for (int i = 0; i < cpe.getEdgeCount(); ++i) {
225        builder->fsCodeAppendf("\t\tedge = dot(%s[%d], vec3(%s.x, %s.y, 1));\n",
226                               edgeArrayName, i, fragmentPos, fragmentPos);
227        if (GrEffectEdgeTypeIsAA(cpe.getEdgeType())) {
228            builder->fsCodeAppend("\t\tedge = clamp(edge, 0.0, 1.0);\n");
229        } else {
230            builder->fsCodeAppend("\t\tedge = edge >= 0.5 ? 1.0 : 0.0;\n");
231        }
232        builder->fsCodeAppend("\t\talpha *= edge;\n");
233    }
234
235    // Woe is me. See skbug.com/2149.
236    if (kTegra2_GrGLRenderer == builder->ctxInfo().renderer()) {
237        builder->fsCodeAppend("\t\tif (-1.0 == alpha) {\n\t\t\tdiscard;\n\t\t}\n");
238    }
239
240    if (GrEffectEdgeTypeIsInverseFill(cpe.getEdgeType())) {
241        builder->fsCodeAppend("\talpha = 1.0 - alpha;\n");
242    }
243    builder->fsCodeAppendf("\t%s = %s;\n", outputColor,
244                           (GrGLSLExpr4(inputColor) * GrGLSLExpr1("alpha")).c_str());
245}
246
247void GrGLConvexPolyEffect::setData(const GrGLUniformManager& uman, const GrDrawEffect& drawEffect) {
248    const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
249    size_t byteSize = 3 * cpe.getEdgeCount() * sizeof(SkScalar);
250    if (0 != memcmp(fPrevEdges, cpe.getEdges(), byteSize)) {
251        uman.set3fv(fEdgeUniform, cpe.getEdgeCount(), cpe.getEdges());
252        memcpy(fPrevEdges, cpe.getEdges(), byteSize);
253    }
254}
255
256GrGLEffect::EffectKey GrGLConvexPolyEffect::GenKey(const GrDrawEffect& drawEffect,
257                                                   const GrGLCaps&) {
258    const GrConvexPolyEffect& cpe = drawEffect.castEffect<GrConvexPolyEffect>();
259    GR_STATIC_ASSERT(kGrEffectEdgeTypeCnt <= 8);
260    return (cpe.getEdgeCount() << 3) | cpe.getEdgeType();
261}
262
263//////////////////////////////////////////////////////////////////////////////
264
265GrEffectRef* GrConvexPolyEffect::Create(GrEffectEdgeType type, const SkPath& path, const SkVector* offset) {
266    if (kHairlineAA_GrEffectEdgeType == type) {
267        return NULL;
268    }
269    if (path.getSegmentMasks() != SkPath::kLine_SegmentMask ||
270        !path.isConvex()) {
271        return NULL;
272    }
273
274    if (path.countPoints() > kMaxEdges) {
275        return NULL;
276    }
277
278    SkPoint pts[kMaxEdges];
279    SkScalar edges[3 * kMaxEdges];
280
281    SkPath::Direction dir;
282    SkAssertResult(path.cheapComputeDirection(&dir));
283
284    SkVector t;
285    if (NULL == offset) {
286        t.set(0, 0);
287    } else {
288        t = *offset;
289    }
290
291    int count = path.getPoints(pts, kMaxEdges);
292    int n = 0;
293    for (int lastPt = count - 1, i = 0; i < count; lastPt = i++) {
294        if (pts[lastPt] != pts[i]) {
295            SkVector v = pts[i] - pts[lastPt];
296            v.normalize();
297            if (SkPath::kCCW_Direction == dir) {
298                edges[3 * n] = v.fY;
299                edges[3 * n + 1] = -v.fX;
300            } else {
301                edges[3 * n] = -v.fY;
302                edges[3 * n + 1] = v.fX;
303            }
304            SkPoint p = pts[i] + t;
305            edges[3 * n + 2] = -(edges[3 * n] * p.fX + edges[3 * n + 1] * p.fY);
306            ++n;
307        }
308    }
309    if (path.isInverseFillType()) {
310        type = GrInvertEffectEdgeType(type);
311    }
312    return Create(type, n, edges);
313}
314
315GrEffectRef* GrConvexPolyEffect::Create(GrEffectEdgeType edgeType, const SkRect& rect) {
316    if (kHairlineAA_GrEffectEdgeType == edgeType){
317        return NULL;
318    }
319    return AARectEffect::Create(edgeType, rect);
320}
321
322GrConvexPolyEffect::~GrConvexPolyEffect() {}
323
324void GrConvexPolyEffect::getConstantColorComponents(GrColor* color, uint32_t* validFlags) const {
325    *validFlags = 0;
326}
327
328const GrBackendEffectFactory& GrConvexPolyEffect::getFactory() const {
329    return GrTBackendEffectFactory<GrConvexPolyEffect>::getInstance();
330}
331
332GrConvexPolyEffect::GrConvexPolyEffect(GrEffectEdgeType edgeType, int n, const SkScalar edges[])
333    : fEdgeType(edgeType)
334    , fEdgeCount(n) {
335    // Factory function should have already ensured this.
336    SkASSERT(n <= kMaxEdges);
337    memcpy(fEdges, edges, 3 * n * sizeof(SkScalar));
338    // Outset the edges by 0.5 so that a pixel with center on an edge is 50% covered in the AA case
339    // and 100% covered in the non-AA case.
340    for (int i = 0; i < n; ++i) {
341        fEdges[3 * i + 2] += SK_ScalarHalf;
342    }
343    this->setWillReadFragmentPosition();
344}
345
346bool GrConvexPolyEffect::onIsEqual(const GrEffect& other) const {
347    const GrConvexPolyEffect& cpe = CastEffect<GrConvexPolyEffect>(other);
348    // ignore the fact that 0 == -0 and just use memcmp.
349    return (cpe.fEdgeType == fEdgeType && cpe.fEdgeCount == fEdgeCount &&
350            0 == memcmp(cpe.fEdges, fEdges, 3 * fEdgeCount * sizeof(SkScalar)));
351}
352
353//////////////////////////////////////////////////////////////////////////////
354
355GR_DEFINE_EFFECT_TEST(GrConvexPolyEffect);
356
357GrEffectRef* GrConvexPolyEffect::TestCreate(SkRandom* random,
358                                            GrContext*,
359                                            const GrDrawTargetCaps& caps,
360                                            GrTexture*[]) {
361    int count = random->nextULessThan(kMaxEdges) + 1;
362    SkScalar edges[kMaxEdges * 3];
363    for (int i = 0; i < 3 * count; ++i) {
364        edges[i] = random->nextSScalar1();
365    }
366
367    GrEffectRef* effect;
368    do {
369        GrEffectEdgeType edgeType = static_cast<GrEffectEdgeType>(
370                                        random->nextULessThan(kGrEffectEdgeTypeCnt));
371        effect = GrConvexPolyEffect::Create(edgeType, count, edges);
372    } while (NULL == effect);
373    return effect;
374}
375