GrGLSLFragmentShaderBuilder.cpp revision 15341a284e78651d2b47b89753044f8d6e7eda0a 
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 "GrGLSLFragmentShaderBuilder.h"
9#include "GrRenderTarget.h"
10#include "GrRenderTargetPriv.h"
11#include "gl/GrGLGpu.h"
12#include "glsl/GrGLSL.h"
13#include "glsl/GrGLSLCaps.h"
14#include "glsl/GrGLSLProgramBuilder.h"
15#include "glsl/GrGLSLUniformHandler.h"
16#include "glsl/GrGLSLVarying.h"
17
18const char* GrGLSLFragmentShaderBuilder::kDstColorName = "_dstColor";
19
20static const char* sample_offset_array_name(GrGLSLFPFragmentBuilder::Coordinates coords) {
21    static const char* kArrayNames[] = {
22        "deviceSpaceSampleOffsets",
23        "windowSpaceSampleOffsets"
24    };
25    return kArrayNames[coords];
26
27    GR_STATIC_ASSERT(0 == GrGLSLFPFragmentBuilder::kSkiaDevice_Coordinates);
28    GR_STATIC_ASSERT(1 == GrGLSLFPFragmentBuilder::kGLSLWindow_Coordinates);
29    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kArrayNames) == GrGLSLFPFragmentBuilder::kLast_Coordinates + 1);
30}
31
32static const char* specific_layout_qualifier_name(GrBlendEquation equation) {
33    SkASSERT(GrBlendEquationIsAdvanced(equation));
34
35    static const char* kLayoutQualifierNames[] = {
36        "blend_support_screen",
37        "blend_support_overlay",
38        "blend_support_darken",
39        "blend_support_lighten",
40        "blend_support_colordodge",
41        "blend_support_colorburn",
42        "blend_support_hardlight",
43        "blend_support_softlight",
44        "blend_support_difference",
45        "blend_support_exclusion",
46        "blend_support_multiply",
47        "blend_support_hsl_hue",
48        "blend_support_hsl_saturation",
49        "blend_support_hsl_color",
50        "blend_support_hsl_luminosity"
51    };
52    return kLayoutQualifierNames[equation - kFirstAdvancedGrBlendEquation];
53
54    GR_STATIC_ASSERT(0 == kScreen_GrBlendEquation - kFirstAdvancedGrBlendEquation);
55    GR_STATIC_ASSERT(1 == kOverlay_GrBlendEquation - kFirstAdvancedGrBlendEquation);
56    GR_STATIC_ASSERT(2 == kDarken_GrBlendEquation - kFirstAdvancedGrBlendEquation);
57    GR_STATIC_ASSERT(3 == kLighten_GrBlendEquation - kFirstAdvancedGrBlendEquation);
58    GR_STATIC_ASSERT(4 == kColorDodge_GrBlendEquation - kFirstAdvancedGrBlendEquation);
59    GR_STATIC_ASSERT(5 == kColorBurn_GrBlendEquation - kFirstAdvancedGrBlendEquation);
60    GR_STATIC_ASSERT(6 == kHardLight_GrBlendEquation - kFirstAdvancedGrBlendEquation);
61    GR_STATIC_ASSERT(7 == kSoftLight_GrBlendEquation - kFirstAdvancedGrBlendEquation);
62    GR_STATIC_ASSERT(8 == kDifference_GrBlendEquation - kFirstAdvancedGrBlendEquation);
63    GR_STATIC_ASSERT(9 == kExclusion_GrBlendEquation - kFirstAdvancedGrBlendEquation);
64    GR_STATIC_ASSERT(10 == kMultiply_GrBlendEquation - kFirstAdvancedGrBlendEquation);
65    GR_STATIC_ASSERT(11 == kHSLHue_GrBlendEquation - kFirstAdvancedGrBlendEquation);
66    GR_STATIC_ASSERT(12 == kHSLSaturation_GrBlendEquation - kFirstAdvancedGrBlendEquation);
67    GR_STATIC_ASSERT(13 == kHSLColor_GrBlendEquation - kFirstAdvancedGrBlendEquation);
68    GR_STATIC_ASSERT(14 == kHSLLuminosity_GrBlendEquation - kFirstAdvancedGrBlendEquation);
69    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kLayoutQualifierNames) ==
70                     kGrBlendEquationCnt - kFirstAdvancedGrBlendEquation);
71}
72
73uint8_t GrGLSLFragmentShaderBuilder::KeyForSurfaceOrigin(GrSurfaceOrigin origin) {
74    SkASSERT(kTopLeft_GrSurfaceOrigin == origin || kBottomLeft_GrSurfaceOrigin == origin);
75    return origin;
76
77    GR_STATIC_ASSERT(1 == kTopLeft_GrSurfaceOrigin);
78    GR_STATIC_ASSERT(2 == kBottomLeft_GrSurfaceOrigin);
79}
80
81GrGLSLFragmentShaderBuilder::GrGLSLFragmentShaderBuilder(GrGLSLProgramBuilder* program)
82    : GrGLSLFragmentBuilder(program)
83    , fSetupFragPosition(false)
84    , fHasCustomColorOutput(false)
85    , fCustomColorOutputIndex(-1)
86    , fHasSecondaryOutput(false)
87    , fUsedSampleOffsetArrays(0)
88    , fHasInitializedSampleMask(false) {
89    fSubstageIndices.push_back(0);
90#ifdef SK_DEBUG
91    fUsedProcessorFeatures = GrProcessor::kNone_RequiredFeatures;
92    fHasReadDstColor = false;
93#endif
94}
95
96bool GrGLSLFragmentShaderBuilder::enableFeature(GLSLFeature feature) {
97    const GrGLSLCaps& glslCaps = *fProgramBuilder->glslCaps();
98    switch (feature) {
99        case kStandardDerivatives_GLSLFeature:
100            if (!glslCaps.shaderDerivativeSupport()) {
101                return false;
102            }
103            if (const char* extension = glslCaps.shaderDerivativeExtensionString()) {
104                this->addFeature(1 << kStandardDerivatives_GLSLFeature, extension);
105            }
106            return true;
107        case kPixelLocalStorage_GLSLFeature:
108            if (glslCaps.pixelLocalStorageSize() <= 0) {
109                return false;
110            }
111            this->addFeature(1 << kPixelLocalStorage_GLSLFeature,
112                             "GL_EXT_shader_pixel_local_storage");
113            return true;
114        case kMultisampleInterpolation_GLSLFeature:
115            if (!glslCaps.multisampleInterpolationSupport()) {
116                return false;
117            }
118            if (const char* extension = glslCaps.multisampleInterpolationExtensionString()) {
119                this->addFeature(1 << kMultisampleInterpolation_GLSLFeature, extension);
120            }
121            return true;
122        default:
123            SkFAIL("Unexpected GLSLFeature requested.");
124            return false;
125    }
126}
127
128SkString GrGLSLFragmentShaderBuilder::ensureCoords2D(const GrShaderVar& coords) {
129    if (kVec3f_GrSLType != coords.getType()) {
130        SkASSERT(kVec2f_GrSLType == coords.getType());
131        return coords.getName();
132    }
133
134    SkString coords2D;
135    coords2D.printf("%s_ensure2D", coords.c_str());
136    this->codeAppendf("\tvec2 %s = %s.xy / %s.z;", coords2D.c_str(), coords.c_str(),
137                      coords.c_str());
138    return coords2D;
139}
140
141const char* GrGLSLFragmentShaderBuilder::fragmentPosition() {
142    SkDEBUGCODE(fUsedProcessorFeatures |= GrProcessor::kFragmentPosition_RequiredFeature;)
143
144    const GrGLSLCaps* glslCaps = fProgramBuilder->glslCaps();
145    // We only declare "gl_FragCoord" when we're in the case where we want to use layout qualifiers
146    // to reverse y. Otherwise it isn't necessary and whether the "in" qualifier appears in the
147    // declaration varies in earlier GLSL specs. So it is simpler to omit it.
148    if (kTopLeft_GrSurfaceOrigin == this->getSurfaceOrigin()) {
149        fSetupFragPosition = true;
150        return "gl_FragCoord";
151    } else if (const char* extension = glslCaps->fragCoordConventionsExtensionString()) {
152        if (!fSetupFragPosition) {
153            if (glslCaps->generation() < k150_GrGLSLGeneration) {
154                this->addFeature(1 << kFragCoordConventions_GLSLPrivateFeature,
155                                 extension);
156            }
157            fInputs.push_back().set(kVec4f_GrSLType,
158                                    GrGLSLShaderVar::kIn_TypeModifier,
159                                    "gl_FragCoord",
160                                    kDefault_GrSLPrecision,
161                                    "origin_upper_left");
162            fSetupFragPosition = true;
163        }
164        return "gl_FragCoord";
165    } else {
166        static const char* kTempName = "tmpXYFragCoord";
167        static const char* kCoordName = "fragCoordYDown";
168        if (!fSetupFragPosition) {
169            const char* rtHeightName;
170
171            fProgramBuilder->addRTHeightUniform("RTHeight", &rtHeightName);
172
173            // The Adreno compiler seems to be very touchy about access to "gl_FragCoord".
174            // Accessing glFragCoord.zw can cause a program to fail to link. Additionally,
175            // depending on the surrounding code, accessing .xy with a uniform involved can
176            // do the same thing. Copying gl_FragCoord.xy into a temp vec2 beforehand
177            // (and only accessing .xy) seems to "fix" things.
178            const char* precision = glslCaps->usesPrecisionModifiers() ? "highp " : "";
179            this->codePrependf("\t%svec4 %s = vec4(%s.x, %s - %s.y, 1.0, 1.0);\n",
180                               precision, kCoordName, kTempName, rtHeightName, kTempName);
181            this->codePrependf("%svec2 %s = gl_FragCoord.xy;", precision, kTempName);
182            fSetupFragPosition = true;
183        }
184        SkASSERT(fProgramBuilder->fUniformHandles.fRTHeightUni.isValid());
185        return kCoordName;
186    }
187}
188
189const char* GrGLSLFragmentShaderBuilder::distanceVectorName() const {
190    return "fsDistanceVector";
191}
192
193void GrGLSLFragmentShaderBuilder::appendOffsetToSample(const char* sampleIdx, Coordinates coords) {
194    SkASSERT(fProgramBuilder->header().fSamplePatternKey);
195    SkDEBUGCODE(fUsedProcessorFeatures |= GrProcessor::kSampleLocations_RequiredFeature);
196    if (kTopLeft_GrSurfaceOrigin == this->getSurfaceOrigin()) {
197        // With a top left origin, device and window space are equal, so we only use device coords.
198        coords = kSkiaDevice_Coordinates;
199    }
200    this->codeAppendf("%s[%s]", sample_offset_array_name(coords), sampleIdx);
201    fUsedSampleOffsetArrays |= (1 << coords);
202}
203
204void GrGLSLFragmentShaderBuilder::maskSampleCoverage(const char* mask, bool invert) {
205    const GrGLSLCaps& glslCaps = *fProgramBuilder->glslCaps();
206    if (!glslCaps.sampleVariablesSupport()) {
207        SkDEBUGFAIL("Attempted to mask sample coverage without support.");
208        return;
209    }
210    if (const char* extension = glslCaps.sampleVariablesExtensionString()) {
211        this->addFeature(1 << kSampleVariables_GLSLPrivateFeature, extension);
212    }
213    if (!fHasInitializedSampleMask) {
214        this->codePrependf("gl_SampleMask[0] = -1;");
215        fHasInitializedSampleMask = true;
216    }
217    if (invert) {
218        this->codeAppendf("gl_SampleMask[0] &= ~(%s);", mask);
219    } else {
220        this->codeAppendf("gl_SampleMask[0] &= %s;", mask);
221    }
222}
223
224void GrGLSLFragmentShaderBuilder::overrideSampleCoverage(const char* mask) {
225    const GrGLSLCaps& glslCaps = *fProgramBuilder->glslCaps();
226    if (!glslCaps.sampleMaskOverrideCoverageSupport()) {
227        SkDEBUGFAIL("Attempted to override sample coverage without support.");
228        return;
229    }
230    SkASSERT(glslCaps.sampleVariablesSupport());
231    if (const char* extension = glslCaps.sampleVariablesExtensionString()) {
232        this->addFeature(1 << kSampleVariables_GLSLPrivateFeature, extension);
233    }
234    if (this->addFeature(1 << kSampleMaskOverrideCoverage_GLSLPrivateFeature,
235                         "GL_NV_sample_mask_override_coverage")) {
236        // Redeclare gl_SampleMask with layout(override_coverage) if we haven't already.
237        fOutputs.push_back().set(kInt_GrSLType, GrShaderVar::kOut_TypeModifier,
238                                 "gl_SampleMask", 1, kHigh_GrSLPrecision,
239                                 "override_coverage");
240    }
241    this->codeAppendf("gl_SampleMask[0] = %s;", mask);
242    fHasInitializedSampleMask = true;
243}
244
245const char* GrGLSLFragmentShaderBuilder::dstColor() {
246    SkDEBUGCODE(fHasReadDstColor = true;)
247
248    const char* override = fProgramBuilder->primitiveProcessor().getDestColorOverride();
249    if (override != nullptr) {
250        return override;
251    }
252
253    const GrGLSLCaps* glslCaps = fProgramBuilder->glslCaps();
254    if (glslCaps->fbFetchSupport()) {
255        this->addFeature(1 << kFramebufferFetch_GLSLPrivateFeature,
256                         glslCaps->fbFetchExtensionString());
257
258        // Some versions of this extension string require declaring custom color output on ES 3.0+
259        const char* fbFetchColorName = glslCaps->fbFetchColorName();
260        if (glslCaps->fbFetchNeedsCustomOutput()) {
261            this->enableCustomOutput();
262            fOutputs[fCustomColorOutputIndex].setTypeModifier(GrShaderVar::kInOut_TypeModifier);
263            fbFetchColorName = DeclaredColorOutputName();
264            // Set the dstColor to an intermediate variable so we don't override it with the output
265            this->codeAppendf("vec4 %s = %s;", kDstColorName, fbFetchColorName);
266        } else {
267            return fbFetchColorName;
268        }
269    }
270    return kDstColorName;
271}
272
273void GrGLSLFragmentShaderBuilder::enableAdvancedBlendEquationIfNeeded(GrBlendEquation equation) {
274    SkASSERT(GrBlendEquationIsAdvanced(equation));
275
276    const GrGLSLCaps& caps = *fProgramBuilder->glslCaps();
277    if (!caps.mustEnableAdvBlendEqs()) {
278        return;
279    }
280
281    this->addFeature(1 << kBlendEquationAdvanced_GLSLPrivateFeature,
282                     "GL_KHR_blend_equation_advanced");
283    if (caps.mustEnableSpecificAdvBlendEqs()) {
284        this->addLayoutQualifier(specific_layout_qualifier_name(equation), kOut_InterfaceQualifier);
285    } else {
286        this->addLayoutQualifier("blend_support_all_equations", kOut_InterfaceQualifier);
287    }
288}
289
290void GrGLSLFragmentShaderBuilder::enableCustomOutput() {
291    if (!fHasCustomColorOutput) {
292        fHasCustomColorOutput = true;
293        fCustomColorOutputIndex = fOutputs.count();
294        fOutputs.push_back().set(kVec4f_GrSLType,
295                                 GrGLSLShaderVar::kOut_TypeModifier,
296                                 DeclaredColorOutputName());
297        fProgramBuilder->finalizeFragmentOutputColor(fOutputs.back());
298    }
299}
300
301void GrGLSLFragmentShaderBuilder::enableSecondaryOutput() {
302    SkASSERT(!fHasSecondaryOutput);
303    fHasSecondaryOutput = true;
304    const GrGLSLCaps& caps = *fProgramBuilder->glslCaps();
305    if (const char* extension = caps.secondaryOutputExtensionString()) {
306        this->addFeature(1 << kBlendFuncExtended_GLSLPrivateFeature, extension);
307    }
308
309    // If the primary output is declared, we must declare also the secondary output
310    // and vice versa, since it is not allowed to use a built-in gl_FragColor and a custom
311    // output. The condition also co-incides with the condition in whici GLES SL 2.0
312    // requires the built-in gl_SecondaryFragColorEXT, where as 3.0 requires a custom output.
313    if (caps.mustDeclareFragmentShaderOutput()) {
314        fOutputs.push_back().set(kVec4f_GrSLType, GrGLSLShaderVar::kOut_TypeModifier,
315                                 DeclaredSecondaryColorOutputName());
316        fProgramBuilder->finalizeFragmentSecondaryColor(fOutputs.back());
317    }
318}
319
320const char* GrGLSLFragmentShaderBuilder::getPrimaryColorOutputName() const {
321    return fHasCustomColorOutput ? DeclaredColorOutputName() : "gl_FragColor";
322}
323
324void GrGLSLFragmentBuilder::declAppendf(const char* fmt, ...) {
325    va_list argp;
326    va_start(argp, fmt);
327    inputs().appendVAList(fmt, argp);
328    va_end(argp);
329}
330
331const char* GrGLSLFragmentShaderBuilder::getSecondaryColorOutputName() const {
332    const GrGLSLCaps& caps = *fProgramBuilder->glslCaps();
333    return caps.mustDeclareFragmentShaderOutput() ? DeclaredSecondaryColorOutputName()
334                                                  : "gl_SecondaryFragColorEXT";
335}
336
337GrSurfaceOrigin GrGLSLFragmentShaderBuilder::getSurfaceOrigin() const {
338    SkASSERT(fProgramBuilder->header().fSurfaceOriginKey);
339    return static_cast<GrSurfaceOrigin>(fProgramBuilder->header().fSurfaceOriginKey);
340
341    GR_STATIC_ASSERT(1 == kTopLeft_GrSurfaceOrigin);
342    GR_STATIC_ASSERT(2 == kBottomLeft_GrSurfaceOrigin);
343}
344
345void GrGLSLFragmentShaderBuilder::onFinalize() {
346    fProgramBuilder->varyingHandler()->getFragDecls(&this->inputs(), &this->outputs());
347    GrGLSLAppendDefaultFloatPrecisionDeclaration(kDefault_GrSLPrecision,
348                                                 *fProgramBuilder->glslCaps(),
349                                                 &this->precisionQualifier());
350    if (fUsedSampleOffsetArrays & (1 << kSkiaDevice_Coordinates)) {
351        this->defineSampleOffsetArray(sample_offset_array_name(kSkiaDevice_Coordinates),
352                                      SkMatrix::MakeTrans(-0.5f, -0.5f));
353    }
354    if (fUsedSampleOffsetArrays & (1 << kGLSLWindow_Coordinates)) {
355        // With a top left origin, device and window space are equal, so we only use device coords.
356        SkASSERT(kBottomLeft_GrSurfaceOrigin == this->getSurfaceOrigin());
357        SkMatrix m;
358        m.setScale(1, -1);
359        m.preTranslate(-0.5f, -0.5f);
360        this->defineSampleOffsetArray(sample_offset_array_name(kGLSLWindow_Coordinates), m);
361    }
362}
363
364void GrGLSLFragmentShaderBuilder::defineSampleOffsetArray(const char* name, const SkMatrix& m) {
365    SkASSERT(fProgramBuilder->caps()->sampleLocationsSupport());
366    const GrPipeline& pipeline = fProgramBuilder->pipeline();
367    const GrRenderTargetPriv& rtp = pipeline.getRenderTarget()->renderTargetPriv();
368    const GrGpu::MultisampleSpecs& specs = rtp.getMultisampleSpecs(pipeline.getStencil());
369    SkSTArray<16, SkPoint, true> offsets;
370    offsets.push_back_n(specs.fEffectiveSampleCnt);
371    m.mapPoints(offsets.begin(), specs.fSampleLocations, specs.fEffectiveSampleCnt);
372    this->definitions().append("const ");
373    if (fProgramBuilder->glslCaps()->usesPrecisionModifiers()) {
374        this->definitions().append("highp ");
375    }
376    this->definitions().appendf("vec2 %s[] = vec2[](", name);
377    for (int i = 0; i < specs.fEffectiveSampleCnt; ++i) {
378        this->definitions().appendf("vec2(%f, %f)", offsets[i].x(), offsets[i].y());
379        this->definitions().append(i + 1 != specs.fEffectiveSampleCnt ? ", " : ");\n");
380    }
381}
382
383void GrGLSLFragmentShaderBuilder::onBeforeChildProcEmitCode() {
384    SkASSERT(fSubstageIndices.count() >= 1);
385    fSubstageIndices.push_back(0);
386    // second-to-last value in the fSubstageIndices stack is the index of the child proc
387    // at that level which is currently emitting code.
388    fMangleString.appendf("_c%d", fSubstageIndices[fSubstageIndices.count() - 2]);
389}
390
391void GrGLSLFragmentShaderBuilder::onAfterChildProcEmitCode() {
392    SkASSERT(fSubstageIndices.count() >= 2);
393    fSubstageIndices.pop_back();
394    fSubstageIndices.back()++;
395    int removeAt = fMangleString.findLastOf('_');
396    fMangleString.remove(removeAt, fMangleString.size() - removeAt);
397}
398