1 /*
2 * Copyright 2017 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 #ifndef GrCCCoverageProcessor_DEFINED
9 #define GrCCCoverageProcessor_DEFINED
10
11 #include "GrCaps.h"
12 #include "GrGeometryProcessor.h"
13 #include "GrPipeline.h"
14 #include "GrShaderCaps.h"
15 #include "SkNx.h"
16 #include "glsl/GrGLSLGeometryProcessor.h"
17 #include "glsl/GrGLSLVarying.h"
18
19 class GrGLSLFPFragmentBuilder;
20 class GrGLSLVertexGeoBuilder;
21 class GrMesh;
22 class GrOpFlushState;
23
24 /**
25 * This is the geometry processor for the simple convex primitive shapes (triangles and closed,
26 * convex bezier curves) from which ccpr paths are composed. The output is a single-channel alpha
27 * value, positive for clockwise shapes and negative for counter-clockwise, that indicates coverage.
28 *
29 * The caller is responsible to draw all primitives as produced by GrCCGeometry into a cleared,
30 * floating point, alpha-only render target using SkBlendMode::kPlus. Once all of a path's
31 * primitives have been drawn, the render target contains a composite coverage count that can then
32 * be used to draw the path (see GrCCPathProcessor).
33 *
34 * To draw primitives, use appendMesh() and draw() (defined below).
35 */
36 class GrCCCoverageProcessor : public GrGeometryProcessor {
37 public:
38 enum class PrimitiveType {
39 kTriangles,
40 kWeightedTriangles, // Triangles (from the tessellator) whose winding magnitude > 1.
41 kQuadratics,
42 kCubics,
43 kConics
44 };
45 static const char* PrimitiveTypeName(PrimitiveType);
46
47 // Defines a single primitive shape with 3 input points (i.e. Triangles and Quadratics).
48 // X,Y point values are transposed.
49 struct TriPointInstance {
50 float fX[3];
51 float fY[3];
52
53 void set(const SkPoint[3], const Sk2f& trans);
54 void set(const SkPoint&, const SkPoint&, const SkPoint&, const Sk2f& trans);
55 void set(const Sk2f& P0, const Sk2f& P1, const Sk2f& P2, const Sk2f& trans);
56 };
57
58 // Defines a single primitive shape with 4 input points, or 3 input points plus a "weight"
59 // parameter duplicated in both lanes of the 4th input (i.e. Cubics, Conics, and Triangles with
60 // a weighted winding number). X,Y point values are transposed.
61 struct QuadPointInstance {
62 float fX[4];
63 float fY[4];
64
65 void set(const SkPoint[4], float dx, float dy);
66 void setW(const SkPoint[3], const Sk2f& trans, float w);
67 void setW(const SkPoint&, const SkPoint&, const SkPoint&, const Sk2f& trans, float w);
68 void setW(const Sk2f& P0, const Sk2f& P1, const Sk2f& P2, const Sk2f& trans, float w);
69 };
70
GrCCCoverageProcessor(GrResourceProvider * rp,PrimitiveType type)71 GrCCCoverageProcessor(GrResourceProvider* rp, PrimitiveType type)
72 : INHERITED(kGrCCCoverageProcessor_ClassID)
73 , fPrimitiveType(type)
74 , fImpl(rp->caps()->shaderCaps()->geometryShaderSupport() ? Impl::kGeometryShader
75 : Impl::kVertexShader) {
76 if (Impl::kGeometryShader == fImpl) {
77 this->initGS();
78 } else {
79 this->initVS(rp);
80 }
81 }
82
83 // GrPrimitiveProcessor overrides.
name()84 const char* name() const override { return PrimitiveTypeName(fPrimitiveType); }
85 #ifdef SK_DEBUG
dumpInfo()86 SkString dumpInfo() const override {
87 return SkStringPrintf("%s\n%s", this->name(), this->INHERITED::dumpInfo().c_str());
88 }
89 #endif
90 void getGLSLProcessorKey(const GrShaderCaps&, GrProcessorKeyBuilder*) const override;
91 GrGLSLPrimitiveProcessor* createGLSLInstance(const GrShaderCaps&) const override;
92
93 #ifdef SK_DEBUG
94 // Increases the 1/2 pixel AA bloat by a factor of debugBloat.
enableDebugBloat(float debugBloat)95 void enableDebugBloat(float debugBloat) { fDebugBloat = debugBloat; }
debugBloatEnabled()96 bool debugBloatEnabled() const { return fDebugBloat > 0; }
debugBloat()97 float debugBloat() const { SkASSERT(this->debugBloatEnabled()); return fDebugBloat; }
98 #endif
99
100 // Appends a GrMesh that will draw the provided instances. The instanceBuffer must be an array
101 // of either TriPointInstance or QuadPointInstance, depending on this processor's RendererPass,
102 // with coordinates in the desired shape's final atlas-space position.
appendMesh(sk_sp<GrBuffer> instanceBuffer,int instanceCount,int baseInstance,SkTArray<GrMesh> * out)103 void appendMesh(sk_sp<GrBuffer> instanceBuffer, int instanceCount, int baseInstance,
104 SkTArray<GrMesh>* out) const {
105 if (Impl::kGeometryShader == fImpl) {
106 this->appendGSMesh(std::move(instanceBuffer), instanceCount, baseInstance, out);
107 } else {
108 this->appendVSMesh(std::move(instanceBuffer), instanceCount, baseInstance, out);
109 }
110 }
111
112 void draw(GrOpFlushState*, const GrPipeline&, const SkIRect scissorRects[], const GrMesh[],
113 int meshCount, const SkRect& drawBounds) const;
114
115 // The Shader provides code to calculate each pixel's coverage in a RenderPass. It also
116 // provides details about shape-specific geometry.
117 class Shader {
118 public:
119 // Called before generating geometry. Subclasses may set up internal member variables during
120 // this time that will be needed during onEmitVaryings (e.g. transformation matrices).
121 //
122 // If the 'outHull4' parameter is provided, and there are not 4 input points, the subclass
123 // is required to fill it with the name of a 4-point hull around which the Impl can generate
124 // its geometry. If it is left unchanged, the Impl will use the regular input points.
125 virtual void emitSetupCode(GrGLSLVertexGeoBuilder*, const char* pts, const char* wind,
126 const char** outHull4 = nullptr) const {
127 SkASSERT(!outHull4);
128 }
129
emitVaryings(GrGLSLVaryingHandler * varyingHandler,GrGLSLVarying::Scope scope,SkString * code,const char * position,const char * coverage,const char * cornerCoverage)130 void emitVaryings(GrGLSLVaryingHandler* varyingHandler, GrGLSLVarying::Scope scope,
131 SkString* code, const char* position, const char* coverage,
132 const char* cornerCoverage) {
133 SkASSERT(GrGLSLVarying::Scope::kVertToGeo != scope);
134 this->onEmitVaryings(varyingHandler, scope, code, position, coverage, cornerCoverage);
135 }
136
137 void emitFragmentCode(const GrCCCoverageProcessor&, GrGLSLFPFragmentBuilder*,
138 const char* skOutputColor, const char* skOutputCoverage) const;
139
140 // Calculates the winding direction of the input points (+1, -1, or 0). Wind for extremely
141 // thin triangles gets rounded to zero.
142 static void CalcWind(const GrCCCoverageProcessor&, GrGLSLVertexGeoBuilder*, const char* pts,
143 const char* outputWind);
144
145 // Defines an equation ("dot(float3(pt, 1), distance_equation)") that is -1 on the outside
146 // border of a conservative raster edge and 0 on the inside. 'leftPt' and 'rightPt' must be
147 // ordered clockwise.
148 static void EmitEdgeDistanceEquation(GrGLSLVertexGeoBuilder*, const char* leftPt,
149 const char* rightPt,
150 const char* outputDistanceEquation);
151
152 // Calculates an edge's coverage at a conservative raster vertex. The edge is defined by two
153 // clockwise-ordered points, 'leftPt' and 'rightPt'. 'rasterVertexDir' is a pair of +/-1
154 // values that point in the direction of conservative raster bloat, starting from an
155 // endpoint.
156 //
157 // Coverage values ramp from -1 (completely outside the edge) to 0 (completely inside).
158 static void CalcEdgeCoverageAtBloatVertex(GrGLSLVertexGeoBuilder*, const char* leftPt,
159 const char* rightPt, const char* rasterVertexDir,
160 const char* outputCoverage);
161
162 // Calculates an edge's coverage at two conservative raster vertices.
163 // (See CalcEdgeCoverageAtBloatVertex).
164 static void CalcEdgeCoveragesAtBloatVertices(GrGLSLVertexGeoBuilder*, const char* leftPt,
165 const char* rightPt, const char* bloatDir1,
166 const char* bloatDir2,
167 const char* outputCoverages);
168
169 // Corner boxes require an additional "attenuation" varying that is multiplied by the
170 // regular (linearly-interpolated) coverage. This function calculates the attenuation value
171 // to use in the single, outermost vertex. The remaining three vertices of the corner box
172 // all use an attenuation value of 1.
173 static void CalcCornerAttenuation(GrGLSLVertexGeoBuilder*, const char* leftDir,
174 const char* rightDir, const char* outputAttenuation);
175
~Shader()176 virtual ~Shader() {}
177
178 protected:
179 // Here the subclass adds its internal varyings to the handler and produces code to
180 // initialize those varyings from a given position and coverage values.
181 //
182 // NOTE: the coverage values are signed appropriately for wind.
183 // 'coverage' will only be +1 or -1 on curves.
184 virtual void onEmitVaryings(GrGLSLVaryingHandler*, GrGLSLVarying::Scope, SkString* code,
185 const char* position, const char* coverage,
186 const char* cornerCoverage) = 0;
187
188 // Emits the fragment code that calculates a pixel's signed coverage value.
189 virtual void onEmitFragmentCode(GrGLSLFPFragmentBuilder*,
190 const char* outputCoverage) const = 0;
191
192 // Returns the name of a Shader's internal varying at the point where where its value is
193 // assigned. This is intended to work whether called for a vertex or a geometry shader.
OutName(const GrGLSLVarying & varying)194 const char* OutName(const GrGLSLVarying& varying) const {
195 using Scope = GrGLSLVarying::Scope;
196 SkASSERT(Scope::kVertToGeo != varying.scope());
197 return Scope::kGeoToFrag == varying.scope() ? varying.gsOut() : varying.vsOut();
198 }
199
200 // Our friendship with GrGLSLShaderBuilder does not propogate to subclasses.
AccessCodeString(GrGLSLShaderBuilder * s)201 inline static SkString& AccessCodeString(GrGLSLShaderBuilder* s) { return s->code(); }
202 };
203
204 private:
205 class GSImpl;
206 class GSTriangleHullImpl;
207 class GSCurveHullImpl;
208 class GSCornerImpl;
209 class VSImpl;
210 class TriangleShader;
211
212 // Slightly undershoot a bloat radius of 0.5 so vertices that fall on integer boundaries don't
213 // accidentally bleed into neighbor pixels.
214 static constexpr float kAABloatRadius = 0.491111f;
215
216 // Number of bezier points for curves, or 3 for triangles.
numInputPoints()217 int numInputPoints() const { return PrimitiveType::kCubics == fPrimitiveType ? 4 : 3; }
218
isTriangles()219 bool isTriangles() const {
220 return PrimitiveType::kTriangles == fPrimitiveType ||
221 PrimitiveType::kWeightedTriangles == fPrimitiveType;
222 }
223
hasInputWeight()224 int hasInputWeight() const {
225 return PrimitiveType::kWeightedTriangles == fPrimitiveType ||
226 PrimitiveType::kConics == fPrimitiveType;
227 }
228
229 enum class Impl : bool {
230 kGeometryShader,
231 kVertexShader
232 };
233
234 // Geometry shader backend draws primitives in two subpasses.
235 enum class GSSubpass : bool {
236 kHulls,
237 kCorners
238 };
239
GrCCCoverageProcessor(const GrCCCoverageProcessor & proc,GSSubpass subpass)240 GrCCCoverageProcessor(const GrCCCoverageProcessor& proc, GSSubpass subpass)
241 : INHERITED(kGrCCCoverageProcessor_ClassID)
242 , fPrimitiveType(proc.fPrimitiveType)
243 , fImpl(Impl::kGeometryShader)
244 SkDEBUGCODE(, fDebugBloat(proc.fDebugBloat))
245 , fGSSubpass(subpass) {
246 SkASSERT(Impl::kGeometryShader == proc.fImpl);
247 this->initGS();
248 }
249
250 void initGS();
251 void initVS(GrResourceProvider*);
252
253 void appendGSMesh(sk_sp<const GrBuffer> instanceBuffer, int instanceCount, int baseInstance,
254 SkTArray<GrMesh>* out) const;
255 void appendVSMesh(sk_sp<const GrBuffer> instanceBuffer, int instanceCount, int baseInstance,
256 SkTArray<GrMesh>* out) const;
257
258 GrGLSLPrimitiveProcessor* createGSImpl(std::unique_ptr<Shader>) const;
259 GrGLSLPrimitiveProcessor* createVSImpl(std::unique_ptr<Shader>) const;
260 // The type and meaning of this attribute depends on whether we're using VSImpl or GSImpl.
261 Attribute fVertexAttribute;
262
263 const PrimitiveType fPrimitiveType;
264 const Impl fImpl;
265 SkDEBUGCODE(float fDebugBloat = 0);
266
267 // Used by GSImpl.
268 const GSSubpass fGSSubpass = GSSubpass::kHulls;
269
270 // Used by VSImpl.
271 Attribute fInstanceAttributes[2];
272 sk_sp<const GrBuffer> fVSVertexBuffer;
273 sk_sp<const GrBuffer> fVSIndexBuffer;
274 int fVSNumIndicesPerInstance;
275 GrPrimitiveType fVSTriangleType;
276
277 typedef GrGeometryProcessor INHERITED;
278 };
279
PrimitiveTypeName(PrimitiveType type)280 inline const char* GrCCCoverageProcessor::PrimitiveTypeName(PrimitiveType type) {
281 switch (type) {
282 case PrimitiveType::kTriangles: return "kTriangles";
283 case PrimitiveType::kWeightedTriangles: return "kWeightedTriangles";
284 case PrimitiveType::kQuadratics: return "kQuadratics";
285 case PrimitiveType::kCubics: return "kCubics";
286 case PrimitiveType::kConics: return "kConics";
287 }
288 SK_ABORT("Invalid PrimitiveType");
289 return "";
290 }
291
set(const SkPoint p[3],const Sk2f & trans)292 inline void GrCCCoverageProcessor::TriPointInstance::set(const SkPoint p[3], const Sk2f& trans) {
293 this->set(p[0], p[1], p[2], trans);
294 }
295
set(const SkPoint & p0,const SkPoint & p1,const SkPoint & p2,const Sk2f & trans)296 inline void GrCCCoverageProcessor::TriPointInstance::set(const SkPoint& p0, const SkPoint& p1,
297 const SkPoint& p2, const Sk2f& trans) {
298 Sk2f P0 = Sk2f::Load(&p0);
299 Sk2f P1 = Sk2f::Load(&p1);
300 Sk2f P2 = Sk2f::Load(&p2);
301 this->set(P0, P1, P2, trans);
302 }
303
set(const Sk2f & P0,const Sk2f & P1,const Sk2f & P2,const Sk2f & trans)304 inline void GrCCCoverageProcessor::TriPointInstance::set(const Sk2f& P0, const Sk2f& P1,
305 const Sk2f& P2, const Sk2f& trans) {
306 Sk2f::Store3(this, P0 + trans, P1 + trans, P2 + trans);
307 }
308
set(const SkPoint p[4],float dx,float dy)309 inline void GrCCCoverageProcessor::QuadPointInstance::set(const SkPoint p[4], float dx, float dy) {
310 Sk4f X,Y;
311 Sk4f::Load2(p, &X, &Y);
312 (X + dx).store(&fX);
313 (Y + dy).store(&fY);
314 }
315
setW(const SkPoint p[3],const Sk2f & trans,float w)316 inline void GrCCCoverageProcessor::QuadPointInstance::setW(const SkPoint p[3], const Sk2f& trans,
317 float w) {
318 this->setW(p[0], p[1], p[2], trans, w);
319 }
320
setW(const SkPoint & p0,const SkPoint & p1,const SkPoint & p2,const Sk2f & trans,float w)321 inline void GrCCCoverageProcessor::QuadPointInstance::setW(const SkPoint& p0, const SkPoint& p1,
322 const SkPoint& p2, const Sk2f& trans,
323 float w) {
324 Sk2f P0 = Sk2f::Load(&p0);
325 Sk2f P1 = Sk2f::Load(&p1);
326 Sk2f P2 = Sk2f::Load(&p2);
327 this->setW(P0, P1, P2, trans, w);
328 }
329
setW(const Sk2f & P0,const Sk2f & P1,const Sk2f & P2,const Sk2f & trans,float w)330 inline void GrCCCoverageProcessor::QuadPointInstance::setW(const Sk2f& P0, const Sk2f& P1,
331 const Sk2f& P2, const Sk2f& trans,
332 float w) {
333 Sk2f W = Sk2f(w);
334 Sk2f::Store4(this, P0 + trans, P1 + trans, P2 + trans, W);
335 }
336
337 #endif
338