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 #ifndef GrGLSLShaderBuilder_DEFINED
9 #define GrGLSLShaderBuilder_DEFINED
10 
11 #include "GrAllocator.h"
12 #include "GrShaderVar.h"
13 #include "glsl/GrGLSLUniformHandler.h"
14 #include "SkTDArray.h"
15 
16 #include <stdarg.h>
17 
18 class GrGLSLColorSpaceXformHelper;
19 
20 /**
21   base class for all shaders builders
22 */
23 class GrGLSLShaderBuilder {
24 public:
25     GrGLSLShaderBuilder(GrGLSLProgramBuilder* program);
26     virtual ~GrGLSLShaderBuilder() {}
27 
28     using SamplerHandle      = GrGLSLUniformHandler::SamplerHandle;
29 
30     /** Appends a 2D texture sample with projection if necessary. coordType must either be Vec2f or
31         Vec3f. The latter is interpreted as projective texture coords. The vec length and swizzle
32         order of the result depends on the GrProcessor::TextureSampler associated with the
33         SamplerHandle.
34         */
35     void appendTextureLookup(SkString* out,
36                              SamplerHandle,
37                              const char* coordName,
38                              GrSLType coordType = kHalf2_GrSLType) const;
39 
40     /** Version of above that appends the result to the shader code instead.*/
41     void appendTextureLookup(SamplerHandle,
42                              const char* coordName,
43                              GrSLType coordType = kHalf2_GrSLType,
44                              GrGLSLColorSpaceXformHelper* colorXformHelper = nullptr);
45 
46 
47     /** Does the work of appendTextureLookup and modulates the result by modulation. The result is
48         always a half4. modulation and the swizzle specified by SamplerHandle must both be
49         half4 or half. If modulation is "" or nullptr it this function acts as though
50         appendTextureLookup were called. */
51     void appendTextureLookupAndModulate(const char* modulation,
52                                         SamplerHandle,
53                                         const char* coordName,
54                                         GrSLType coordType = kHalf2_GrSLType,
55                                         GrGLSLColorSpaceXformHelper* colorXformHelper = nullptr);
56 
57     /** Adds a helper function to facilitate color gamut transformation, and produces code that
58         returns the srcColor transformed into a new gamut (via multiplication by the xform from
59         colorXformHelper). Premultiplied sources are also handled correctly (colorXformHelper
60         determines if the source is premultipled or not). */
61     void appendColorGamutXform(SkString* out, const char* srcColor,
62                                GrGLSLColorSpaceXformHelper* colorXformHelper);
63 
64     /** Version of above that appends the result to the shader code instead. */
65     void appendColorGamutXform(const char* srcColor, GrGLSLColorSpaceXformHelper* colorXformHelper);
66 
67     /**
68     * Adds a constant declaration to the top of the shader.
69     */
70     void defineConstant(const char* type, const char* name, const char* value) {
71         this->definitions().appendf("const %s %s = %s;\n", type, name, value);
72     }
73 
74     void defineConstant(const char* name, int value) {
75         this->definitions().appendf("const int %s = %i;\n", name, value);
76     }
77 
78     void defineConstant(const char* name, float value) {
79         this->definitions().appendf("const float %s = %f;\n", name, value);
80     }
81 
82     void defineConstantf(const char* type, const char* name, const char* fmt, ...) {
83        this->definitions().appendf("const %s %s = ", type, name);
84        va_list args;
85        va_start(args, fmt);
86        this->definitions().appendVAList(fmt, args);
87        va_end(args);
88        this->definitions().append(";\n");
89     }
90 
91     void declareGlobal(const GrShaderVar&);
92 
93     /**
94     * Called by GrGLSLProcessors to add code to one of the shaders.
95     */
96     void codeAppendf(const char format[], ...) SK_PRINTF_LIKE(2, 3) {
97        va_list args;
98        va_start(args, format);
99        this->code().appendVAList(format, args);
100        va_end(args);
101     }
102 
103     void codeAppend(const char* str) { this->code().append(str); }
104 
105     void codeAppend(const char* str, size_t length) { this->code().append(str, length); }
106 
107     void codePrependf(const char format[], ...) SK_PRINTF_LIKE(2, 3) {
108        va_list args;
109        va_start(args, format);
110        this->code().prependVAList(format, args);
111        va_end(args);
112     }
113 
114     /**
115      * Appends a variable declaration to one of the shaders
116      */
117     void declAppend(const GrShaderVar& var);
118 
119     /** Emits a helper function outside of main() in the fragment shader. */
120     void emitFunction(GrSLType returnType,
121                       const char* name,
122                       int argCnt,
123                       const GrShaderVar* args,
124                       const char* body,
125                       SkString* outName);
126 
127     /*
128      * Combines the various parts of the shader to create a single finalized shader string.
129      */
130     void finalize(uint32_t visibility);
131 
132     /*
133      * Get parent builder for adding uniforms
134      */
135     GrGLSLProgramBuilder* getProgramBuilder() { return fProgramBuilder; }
136 
137     /**
138      * Helper for begining and ending a block in the shader code.
139      */
140     class ShaderBlock {
141     public:
142         ShaderBlock(GrGLSLShaderBuilder* builder) : fBuilder(builder) {
143             SkASSERT(builder);
144             fBuilder->codeAppend("{");
145         }
146 
147         ~ShaderBlock() {
148             fBuilder->codeAppend("}");
149         }
150     private:
151         GrGLSLShaderBuilder* fBuilder;
152     };
153 
154 protected:
155     typedef GrTAllocator<GrShaderVar> VarArray;
156     void appendDecls(const VarArray& vars, SkString* out) const;
157 
158     /**
159      * Features that should only be enabled internally by the builders.
160      */
161     enum GLSLPrivateFeature {
162         kFragCoordConventions_GLSLPrivateFeature,
163         kBlendEquationAdvanced_GLSLPrivateFeature,
164         kBlendFuncExtended_GLSLPrivateFeature,
165         kFramebufferFetch_GLSLPrivateFeature,
166         kNoPerspectiveInterpolation_GLSLPrivateFeature,
167         kLastGLSLPrivateFeature = kNoPerspectiveInterpolation_GLSLPrivateFeature
168     };
169 
170     /*
171      * A general function which enables an extension in a shader if the feature bit is not present
172      *
173      * @return true if the feature bit was not yet present, false otherwise.
174      */
175     bool addFeature(uint32_t featureBit, const char* extensionName);
176 
177     enum InterfaceQualifier {
178         kIn_InterfaceQualifier,
179         kOut_InterfaceQualifier,
180         kLastInterfaceQualifier = kOut_InterfaceQualifier
181     };
182 
183     /*
184      * A low level function to build default layout qualifiers.
185      *
186      *   e.g. layout(param1, param2, ...) out;
187      *
188      * GLSL allows default layout qualifiers for in, out, and uniform.
189      */
190     void addLayoutQualifier(const char* param, InterfaceQualifier);
191 
192     void compileAndAppendLayoutQualifiers();
193 
194     void nextStage() {
195         fShaderStrings.push_back();
196         fCompilerStrings.push_back(this->code().c_str());
197         fCompilerStringLengths.push_back((int)this->code().size());
198         fCodeIndex++;
199     }
200 
201     SkString& versionDecl() { return fShaderStrings[kVersionDecl]; }
202     SkString& extensions() { return fShaderStrings[kExtensions]; }
203     SkString& definitions() { return fShaderStrings[kDefinitions]; }
204     SkString& precisionQualifier() { return fShaderStrings[kPrecisionQualifier]; }
205     SkString& layoutQualifiers() { return fShaderStrings[kLayoutQualifiers]; }
206     SkString& uniforms() { return fShaderStrings[kUniforms]; }
207     SkString& inputs() { return fShaderStrings[kInputs]; }
208     SkString& outputs() { return fShaderStrings[kOutputs]; }
209     SkString& functions() { return fShaderStrings[kFunctions]; }
210     SkString& main() { return fShaderStrings[kMain]; }
211     SkString& code() { return fShaderStrings[fCodeIndex]; }
212 
213     virtual void onFinalize() = 0;
214 
215     enum {
216         kVersionDecl,
217         kExtensions,
218         kDefinitions,
219         kPrecisionQualifier,
220         kLayoutQualifiers,
221         kUniforms,
222         kInputs,
223         kOutputs,
224         kFunctions,
225         kMain,
226         kCode,
227     };
228 
229     GrGLSLProgramBuilder* fProgramBuilder;
230     SkSTArray<kCode, const char*, true> fCompilerStrings;
231     SkSTArray<kCode, int, true> fCompilerStringLengths;
232     SkSTArray<kCode, SkString> fShaderStrings;
233     SkString fCode;
234     SkString fFunctions;
235     SkString fExtensions;
236 
237     VarArray fInputs;
238     VarArray fOutputs;
239     uint32_t fFeaturesAddedMask;
240     SkSTArray<1, SkString> fLayoutParams[kLastInterfaceQualifier + 1];
241     int fCodeIndex;
242     bool fFinalized;
243 
244     friend class GrCCCoverageProcessor; // to access code().
245     friend class GrGLSLProgramBuilder;
246     friend class GrGLProgramBuilder;
247     friend class GrGLSLVaryingHandler; // to access noperspective interpolation feature.
248     friend class GrGLPathProgramBuilder; // to access fInputs.
249     friend class GrVkPipelineStateBuilder;
250     friend class GrMtlPipelineStateBuilder;
251 };
252 #endif
253