1 /*
2 * Copyright 2016 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 "SkNormalMapSource.h"
9
10 #include "SkArenaAlloc.h"
11 #include "SkLightingShader.h"
12 #include "SkMatrix.h"
13 #include "SkNormalSource.h"
14 #include "SkReadBuffer.h"
15 #include "SkWriteBuffer.h"
16
17 #if SK_SUPPORT_GPU
18 #include "GrCoordTransform.h"
19 #include "glsl/GrGLSLFragmentProcessor.h"
20 #include "glsl/GrGLSLFragmentShaderBuilder.h"
21 #include "SkGr.h"
22
23 class NormalMapFP : public GrFragmentProcessor {
24 public:
Make(std::unique_ptr<GrFragmentProcessor> mapFP,const SkMatrix & invCTM)25 static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> mapFP,
26 const SkMatrix& invCTM) {
27 return std::unique_ptr<GrFragmentProcessor>(new NormalMapFP(std::move(mapFP), invCTM));
28 }
29
name() const30 const char* name() const override { return "NormalMapFP"; }
31
invCTM() const32 const SkMatrix& invCTM() const { return fInvCTM; }
33
clone() const34 std::unique_ptr<GrFragmentProcessor> clone() const override {
35 return Make(this->childProcessor(0).clone(), fInvCTM);
36 }
37
38 private:
39 class GLSLNormalMapFP : public GrGLSLFragmentProcessor {
40 public:
GLSLNormalMapFP()41 GLSLNormalMapFP() : fColumnMajorInvCTM22{0.0f} {}
42
emitCode(EmitArgs & args)43 void emitCode(EmitArgs& args) override {
44 GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
45 GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
46
47 // add uniform
48 const char* xformUniName = nullptr;
49 fXformUni = uniformHandler->addUniform(kFragment_GrShaderFlag, kFloat2x2_GrSLType,
50 "Xform", &xformUniName);
51
52 SkString dstNormalColorName("dstNormalColor");
53 this->emitChild(0, &dstNormalColorName, args);
54 fragBuilder->codeAppendf("float3 normal = normalize(%s.rgb - float3(0.5));",
55 dstNormalColorName.c_str());
56
57 // If there's no x & y components, return (0, 0, +/- 1) instead to avoid division by 0
58 fragBuilder->codeAppend( "if (abs(normal.z) > 0.999) {");
59 fragBuilder->codeAppendf(" %s = normalize(half4(0.0, 0.0, half(normal.z), 0.0));",
60 args.fOutputColor);
61 // Else, Normalizing the transformed X and Y, while keeping constant both Z and the
62 // vector's angle in the XY plane. This maintains the "slope" for the surface while
63 // appropriately rotating the normal regardless of any anisotropic scaling that occurs.
64 // Here, we call 'scaling factor' the number that must divide the transformed X and Y so
65 // that the normal's length remains equal to 1.
66 fragBuilder->codeAppend( "} else {");
67 fragBuilder->codeAppendf(" float2 transformed = %s * normal.xy;",
68 xformUniName);
69 fragBuilder->codeAppend( " float scalingFactorSquared = "
70 "( (transformed.x * transformed.x) "
71 "+ (transformed.y * transformed.y) )"
72 "/(1.0 - (normal.z * normal.z));");
73 fragBuilder->codeAppendf(" %s = half4(half2(transformed * "
74 "inversesqrt(scalingFactorSquared)),"
75 "half(normal.z), 0.0);",
76 args.fOutputColor);
77 fragBuilder->codeAppend( "}");
78 }
79
GenKey(const GrProcessor &,const GrShaderCaps &,GrProcessorKeyBuilder * b)80 static void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder* b) {
81 b->add32(0x0);
82 }
83
84 private:
onSetData(const GrGLSLProgramDataManager & pdman,const GrFragmentProcessor & proc)85 void onSetData(const GrGLSLProgramDataManager& pdman,
86 const GrFragmentProcessor& proc) override {
87 const NormalMapFP& normalMapFP = proc.cast<NormalMapFP>();
88
89 const SkMatrix& invCTM = normalMapFP.invCTM();
90 fColumnMajorInvCTM22[0] = invCTM.get(SkMatrix::kMScaleX);
91 fColumnMajorInvCTM22[1] = invCTM.get(SkMatrix::kMSkewY);
92 fColumnMajorInvCTM22[2] = invCTM.get(SkMatrix::kMSkewX);
93 fColumnMajorInvCTM22[3] = invCTM.get(SkMatrix::kMScaleY);
94 pdman.setMatrix2f(fXformUni, fColumnMajorInvCTM22);
95 }
96
97 private:
98 // Upper-right 2x2 corner of the inverse of the CTM in column-major form
99 float fColumnMajorInvCTM22[4];
100 GrGLSLProgramDataManager::UniformHandle fXformUni;
101 };
102
onGetGLSLProcessorKey(const GrShaderCaps & caps,GrProcessorKeyBuilder * b) const103 void onGetGLSLProcessorKey(const GrShaderCaps& caps, GrProcessorKeyBuilder* b) const override {
104 GLSLNormalMapFP::GenKey(*this, caps, b);
105 }
NormalMapFP(std::unique_ptr<GrFragmentProcessor> mapFP,const SkMatrix & invCTM)106 NormalMapFP(std::unique_ptr<GrFragmentProcessor> mapFP, const SkMatrix& invCTM)
107 : INHERITED(kMappedNormalsFP_ClassID, kNone_OptimizationFlags)
108 , fInvCTM(invCTM) {
109 this->registerChildProcessor(std::move(mapFP));
110 }
111
onCreateGLSLInstance() const112 GrGLSLFragmentProcessor* onCreateGLSLInstance() const override { return new GLSLNormalMapFP; }
113
onIsEqual(const GrFragmentProcessor & proc) const114 bool onIsEqual(const GrFragmentProcessor& proc) const override {
115 const NormalMapFP& normalMapFP = proc.cast<NormalMapFP>();
116 return fInvCTM == normalMapFP.fInvCTM;
117 }
118
119 SkMatrix fInvCTM;
120
121 typedef GrFragmentProcessor INHERITED;
122 };
123
asFragmentProcessor(const GrFPArgs & args) const124 std::unique_ptr<GrFragmentProcessor> SkNormalMapSourceImpl::asFragmentProcessor(
125 const GrFPArgs& args) const {
126 std::unique_ptr<GrFragmentProcessor> mapFP = as_SB(fMapShader)->asFragmentProcessor(args);
127 if (!mapFP) {
128 return nullptr;
129 }
130
131 return NormalMapFP::Make(std::move(mapFP), fInvCTM);
132 }
133
134 #endif // SK_SUPPORT_GPU
135
136 ////////////////////////////////////////////////////////////////////////////
137
Provider(const SkNormalMapSourceImpl & source,SkShaderBase::Context * mapContext)138 SkNormalMapSourceImpl::Provider::Provider(const SkNormalMapSourceImpl& source,
139 SkShaderBase::Context* mapContext)
140 : fSource(source)
141 , fMapContext(mapContext) {}
142
asProvider(const SkShaderBase::ContextRec & rec,SkArenaAlloc * alloc) const143 SkNormalSource::Provider* SkNormalMapSourceImpl::asProvider(const SkShaderBase::ContextRec &rec,
144 SkArenaAlloc* alloc) const {
145 SkMatrix normTotalInv;
146 if (!this->computeNormTotalInverse(rec, &normTotalInv)) {
147 return nullptr;
148 }
149
150 // Normals really aren't colors, so to ensure we can always make the context, we ignore
151 // the rec's colorspace
152 SkColorSpace* dstColorSpace = nullptr;
153
154 // Overriding paint's alpha because we need the normal map's RGB channels to be unpremul'd
155 SkPaint overridePaint {*(rec.fPaint)};
156 overridePaint.setAlpha(0xFF);
157 SkShaderBase::ContextRec overrideRec(overridePaint, *(rec.fMatrix), rec.fLocalMatrix,
158 rec.fDstColorType, dstColorSpace);
159
160 auto* context = as_SB(fMapShader)->makeContext(overrideRec, alloc);
161 if (!context) {
162 return nullptr;
163 }
164
165 return alloc->make<Provider>(*this, context);
166 }
167
computeNormTotalInverse(const SkShaderBase::ContextRec & rec,SkMatrix * normTotalInverse) const168 bool SkNormalMapSourceImpl::computeNormTotalInverse(const SkShaderBase::ContextRec& rec,
169 SkMatrix* normTotalInverse) const {
170 SkMatrix total = SkMatrix::Concat(*rec.fMatrix, fMapShader->getLocalMatrix());
171 if (rec.fLocalMatrix) {
172 total.preConcat(*rec.fLocalMatrix);
173 }
174
175 return total.invert(normTotalInverse);
176 }
177
178 #define BUFFER_MAX 16
fillScanLine(int x,int y,SkPoint3 output[],int count) const179 void SkNormalMapSourceImpl::Provider::fillScanLine(int x, int y, SkPoint3 output[],
180 int count) const {
181 SkPMColor tmpNormalColors[BUFFER_MAX];
182
183 do {
184 int n = SkTMin(count, BUFFER_MAX);
185
186 fMapContext->shadeSpan(x, y, tmpNormalColors, n);
187
188 for (int i = 0; i < n; i++) {
189 SkPoint3 tempNorm;
190
191 tempNorm.set(SkIntToScalar(SkGetPackedR32(tmpNormalColors[i])) - 127.0f,
192 SkIntToScalar(SkGetPackedG32(tmpNormalColors[i])) - 127.0f,
193 SkIntToScalar(SkGetPackedB32(tmpNormalColors[i])) - 127.0f);
194
195 tempNorm.normalize();
196
197
198 if (!SkScalarNearlyEqual(SkScalarAbs(tempNorm.fZ), 1.0f)) {
199 SkVector transformed = fSource.fInvCTM.mapVector(tempNorm.fX, tempNorm.fY);
200
201 // Normalizing the transformed X and Y, while keeping constant both Z and the
202 // vector's angle in the XY plane. This maintains the "slope" for the surface while
203 // appropriately rotating the normal for any anisotropic scaling that occurs.
204 // Here, we call scaling factor the number that must divide the transformed X and Y
205 // so that the normal's length remains equal to 1.
206 SkScalar scalingFactorSquared =
207 (SkScalarSquare(transformed.fX) + SkScalarSquare(transformed.fY))
208 / (1.0f - SkScalarSquare(tempNorm.fZ));
209 SkScalar invScalingFactor = SkScalarInvert(SkScalarSqrt(scalingFactorSquared));
210
211 output[i].fX = transformed.fX * invScalingFactor;
212 output[i].fY = transformed.fY * invScalingFactor;
213 output[i].fZ = tempNorm.fZ;
214 } else {
215 output[i] = {0.0f, 0.0f, tempNorm.fZ};
216 output[i].normalize();
217 }
218
219 SkASSERT(SkScalarNearlyEqual(output[i].length(), 1.0f));
220 }
221
222 output += n;
223 x += n;
224 count -= n;
225 } while (count > 0);
226 }
227
228 ////////////////////////////////////////////////////////////////////////////////
229
CreateProc(SkReadBuffer & buf)230 sk_sp<SkFlattenable> SkNormalMapSourceImpl::CreateProc(SkReadBuffer& buf) {
231
232 sk_sp<SkShader> mapShader = buf.readFlattenable<SkShaderBase>();
233
234 SkMatrix invCTM;
235 buf.readMatrix(&invCTM);
236
237 return sk_make_sp<SkNormalMapSourceImpl>(std::move(mapShader), invCTM);
238 }
239
flatten(SkWriteBuffer & buf) const240 void SkNormalMapSourceImpl::flatten(SkWriteBuffer& buf) const {
241 this->INHERITED::flatten(buf);
242
243 buf.writeFlattenable(fMapShader.get());
244 buf.writeMatrix(fInvCTM);
245 }
246
247 ////////////////////////////////////////////////////////////////////////////
248
MakeFromNormalMap(sk_sp<SkShader> map,const SkMatrix & ctm)249 sk_sp<SkNormalSource> SkNormalSource::MakeFromNormalMap(sk_sp<SkShader> map, const SkMatrix& ctm) {
250 SkMatrix invCTM;
251
252 if (!ctm.invert(&invCTM) || !map) {
253 return nullptr;
254 }
255
256 return sk_make_sp<SkNormalMapSourceImpl>(std::move(map), invCTM);
257 }
258