source/glsl/finalize.cpp

   1 #include <msp/core/algorithm.h>
   2 #include <msp/core/hash.h>
   3 #include <msp/core/raii.h>
   4 #include <msp/strings/lexicalcast.h>
   5 #include "finalize.h"
   6 #include "glsl_error.h"
   7 #include "reflect.h"
   8
   9 using namespace std;
  10
  11 namespace Msp {
  12 namespace GL {
  13 namespace SL {
  14
  15 void StructOrganizer::visit(StructDeclaration &strct)
  16 {
  17         SetForScope<int> set_offset(offset, 0);
  18         TraversingVisitor::visit(strct);
  19 }
  20
  21 void StructOrganizer::visit(VariableDeclaration &var)
  22 {
  23         if(offset>=0)
  24         {
  25                 int *layout_offset = 0;
  26                 bool has_matrix_order = false;
  27                 if(var.layout)
  28                 {
  29                         for(Layout::Qualifier &q: var.layout->qualifiers)
  30                         {
  31                                 if(q.name=="offset" && q.has_value)
  32                                 {
  33                                         layout_offset = &q.value;
  34                                         if(q.value>=offset)
  35                                                 offset = q.value;
  36                                 }
  37                                 else if(q.name=="column_major" || q.name=="row_major")
  38                                         has_matrix_order = true;
  39                         }
  40                 }
  41
  42                 MemoryRequirementsCalculator::Result mem_reqs = MemoryRequirementsCalculator().apply(var);
  43                 offset += mem_reqs.alignment-1;
  44                 offset -= offset%mem_reqs.alignment;
  45
  46                 if(layout_offset)
  47                         *layout_offset = offset;
  48                 else
  49                         add_layout_qualifier(var.layout, Layout::Qualifier("offset", offset));
  50
  51                 if(!has_matrix_order)
  52                 {
  53                         const BasicTypeDeclaration *basic = dynamic_cast<const BasicTypeDeclaration *>(var.type_declaration);
  54                         while(basic && basic->kind==BasicTypeDeclaration::ARRAY)
  55                                 basic = dynamic_cast<const BasicTypeDeclaration *>(basic->base_type);
  56                         if(basic && basic->kind==BasicTypeDeclaration::MATRIX)
  57                                 add_layout_qualifier(var.layout, Layout::Qualifier("column_major"));
  58                 }
  59
  60                 offset += mem_reqs.size;
  61         }
  62 }
  63
  64
  65 void LocationAllocator::apply(Module &module, const Features &f, bool a)
  66 {
  67         features = f;
  68         alloc_new = a;
  69         for(Stage &s: module.stages)
  70                 apply(s);
  71
  72         if(features.target_api!=VULKAN)
  73                 allocate_locations("uniform");
  74
  75         for(VariableDeclaration *b: unbound_blocks)
  76                 bind_uniform(b->layout, b->block_declaration->block_name, features.uniform_binding_range);
  77         for(VariableDeclaration *t: unbound_textures)
  78                 bind_uniform(t->layout, t->name, features.texture_binding_range);
  79 }
  80
  81 void LocationAllocator::apply(Stage &stage)
  82 {
  83         swap(used_locations["in"], used_locations["out"]);
  84         used_locations["out"].clear();
  85
  86         stage.content.visit(*this);
  87
  88         allocate_locations("in");
  89         allocate_locations("out");
  90 }
  91
  92 void LocationAllocator::allocate_locations(const string &iface)
  93 {
  94         auto write = unplaced_variables.begin();
  95         unsigned next = 0;
  96         for(auto i=unplaced_variables.begin(); i!=unplaced_variables.end(); ++i)
  97         {
  98                 if((*i)->interface!=iface)
  99                 {
 100                         if(write!=i)
 101                                 *write = *i;
 102                         ++write;
 103                         continue;
 104                 }
 105
 106                 if((*i)->interface=="uniform")
 107                 {
 108                         auto j = uniforms.find((*i)->name);
 109                         if(j!=uniforms.end() && j->second.location>=0)
 110                         {
 111                                 add_layout_qualifier((*i)->layout, Layout::Qualifier("location", j->second.location));
 112                                 continue;
 113                         }
 114                 }
 115
 116                 if(!alloc_new)
 117                         continue;
 118
 119                 set<unsigned> &used = used_locations[(*i)->interface];
 120
 121                 unsigned size = LocationCounter().apply(**i);
 122                 while(1)
 123                 {
 124                         int blocking = -1;
 125                         for(unsigned j=0; j<size; ++j)
 126                                 if(used.count(next+j))
 127                                         blocking = next+j;
 128                         if(blocking<0)
 129                                 break;
 130                         next = blocking+1;
 131                 }
 132
 133                 add_layout_qualifier((*i)->layout, Layout::Qualifier("location", next));
 134                 if((*i)->interface=="uniform")
 135                         uniforms[(*i)->name].location = next;
 136
 137                 for(unsigned j=0; j<size; ++j)
 138                         used.insert(next+j);
 139                 next += size;
 140         }
 141
 142         unplaced_variables.erase(write, unplaced_variables.end());
 143 }
 144
 145 void LocationAllocator::bind_uniform(RefPtr<Layout> &layout, const string &name, unsigned range)
 146 {
 147         auto i = uniforms.find(name);
 148
 149         int desc_set = (i!=uniforms.end() ? i->second.desc_set : 0);
 150         if(features.target_api==VULKAN && get_layout_value(layout.get(), "set")<0)
 151                 add_layout_qualifier(layout, Layout::Qualifier("set", desc_set));
 152
 153         if(i!=uniforms.end() && i->second.bind_point>=0)
 154                 add_layout_qualifier(layout, Layout::Qualifier("binding", i->second.bind_point));
 155         else if(alloc_new)
 156         {
 157                 set<unsigned> &used = used_bindings[desc_set];
 158
 159                 unsigned bind_point = hash_fold<32>(hash<64>(name))%range;
 160                 while(used.count(bind_point))
 161                         bind_point = (bind_point+1)%range;
 162
 163                 add_layout_qualifier(layout, Layout::Qualifier("binding", bind_point));
 164                 uniforms[name].bind_point = bind_point;
 165                 used.insert(bind_point);
 166         }
 167 }
 168
 169 bool LocationAllocator::visit_uniform(const string &name, RefPtr<Layout> &layout)
 170 {
 171         int desc_set = get_layout_value(layout.get(), "set");
 172         int bind_point = get_layout_value(layout.get(), "binding");
 173
 174         if(features.target_api==VULKAN)
 175         {
 176                 if(desc_set<0 && bind_point>=0)
 177                 {
 178                         desc_set = 0;
 179                         add_layout_qualifier(layout, Layout::Qualifier("set", desc_set));
 180                 }
 181
 182                 if(desc_set>=0)
 183                         uniforms[name].desc_set = desc_set;
 184         }
 185         else if(desc_set>=0 && bind_point<0)
 186         {
 187                 auto i = find_member(layout->qualifiers, string("set"), &Layout::Qualifier::name);
 188                 layout->qualifiers.erase(i);
 189         }
 190
 191         if(bind_point>=0)
 192         {
 193                 used_bindings[desc_set].insert(bind_point);
 194                 uniforms[name].bind_point = bind_point;
 195         }
 196
 197         return bind_point>=0;
 198 }
 199
 200 void LocationAllocator::visit(VariableDeclaration &var)
 201 {
 202         if(!var.name.compare(0, 3, "gl_"))
 203                 return;
 204
 205         if(!var.interface.empty() && !var.block_declaration)
 206         {
 207                 int location = get_layout_value(var.layout.get(), "location");
 208
 209                 if(location<0 && var.linked_declaration && var.linked_declaration->layout)
 210                 {
 211                         location = get_layout_value(var.linked_declaration->layout.get(), "location");
 212                         if(location>=0)
 213                                 add_layout_qualifier(var.layout, Layout::Qualifier("location", location));
 214                 }
 215
 216                 if(location>=0)
 217                 {
 218                         unsigned size = LocationCounter().apply(var);
 219                         for(unsigned i=0; i<size; ++i)
 220                                 used_locations[var.interface].insert(location+i);
 221                         if(var.interface=="uniform")
 222                                 uniforms[var.name].location = location;
 223                 }
 224                 else
 225                         unplaced_variables.push_back(&var);
 226         }
 227
 228         if(var.interface=="uniform")
 229         {
 230                 if(var.block_declaration)
 231                 {
 232                         bool push_constant = has_layout_qualifier(var.layout.get(), "push_constant");
 233                         if(!push_constant && !visit_uniform(var.block_declaration->block_name, var.layout))
 234                                 unbound_blocks.push_back(&var);
 235                 }
 236                 else
 237                 {
 238                         const TypeDeclaration *base_type = get_ultimate_base_type(var.type_declaration);
 239                         if(dynamic_cast<const ImageTypeDeclaration *>(base_type) && !visit_uniform(var.name, var.layout))
 240                                 unbound_textures.push_back(&var);
 241                 }
 242         }
 243 }
 244
 245
 246 void DepthRangeConverter::apply(Stage &stage, const Features &features)
 247 {
 248         if(stage.type!=Stage::VERTEX || features.target_api==VULKAN)
 249                 return;
 250
 251         stage.content.visit(*this);
 252 }
 253
 254 void DepthRangeConverter::visit(FunctionDeclaration &func)
 255 {
 256         if(func.definition==&func && func.name=="main")
 257         {
 258                 VariableReference *position = new VariableReference;
 259                 position->name = "gl_Position";
 260
 261                 MemberAccess *z = new MemberAccess;
 262                 z->left = position;
 263                 z->member = "z";
 264
 265                 Literal *scale = new Literal;
 266                 scale->token = "2.0";
 267                 scale->value = 2.0f;
 268
 269                 BinaryExpression *multiply = new BinaryExpression;
 270                 multiply->oper = &Operator::get_operator("*", Operator::BINARY);
 271                 multiply->left = z;
 272                 multiply->right = scale;
 273
 274                 MemberAccess *w = new MemberAccess;
 275                 w->left = position->clone();
 276                 w->member = "w";
 277
 278                 BinaryExpression *subtract = new BinaryExpression;
 279                 subtract->oper = &Operator::get_operator("-", Operator::BINARY);
 280                 subtract->left = multiply;
 281                 subtract->right = w;
 282
 283                 Assignment *assign = new Assignment;
 284                 assign->oper = &Operator::get_operator("=", Operator::BINARY);
 285                 assign->left = z->clone();
 286                 assign->right = subtract;
 287
 288                 ExpressionStatement *statement = new ExpressionStatement;
 289                 statement->expression = assign;
 290
 291                 func.body.body.push_back(statement);
 292         }
 293 }
 294
 295
 296 void PrecisionConverter::apply(Stage &s)
 297 {
 298         stage = &s;
 299         s.content.visit(*this);
 300         NodeRemover().apply(s, nodes_to_remove);
 301 }
 302
 303 void PrecisionConverter::visit(Block &block)
 304 {
 305         for(auto i=block.body.begin(); i!=block.body.end(); ++i)
 306         {
 307                 if(&block==&stage->content)
 308                         insert_point = i;
 309                 (*i)->visit(*this);
 310         }
 311 }
 312
 313 void PrecisionConverter::visit(Precision &prec)
 314 {
 315         if(stage->required_features.target_api==OPENGL_ES)
 316                 have_default.insert(prec.type);
 317         else
 318                 nodes_to_remove.insert(&prec);
 319 }
 320
 321 void PrecisionConverter::visit(VariableDeclaration &var)
 322 {
 323         if(stage->required_features.target_api!=OPENGL_ES)
 324         {
 325                 var.precision.clear();
 326                 return;
 327         }
 328
 329         const char *default_prec = (stage->type==Stage::FRAGMENT ? "mediump" : "highp");
 330         const TypeDeclaration *type = var.type_declaration;
 331         while(type)
 332         {
 333                 if(dynamic_cast<const ImageTypeDeclaration *>(type))
 334                 {
 335                         default_prec = "lowp";
 336                         break;
 337                 }
 338                 else if(const BasicTypeDeclaration *basic = dynamic_cast<const BasicTypeDeclaration *>(type))
 339                 {
 340                         if(basic->kind==BasicTypeDeclaration::INT || basic->kind==BasicTypeDeclaration::FLOAT)
 341                                 break;
 342                         type = basic->base_type;
 343                 }
 344                 else
 345                         return;
 346         }
 347         if(!type)
 348                 return;
 349
 350         if(!have_default.count(type->name))
 351         {
 352                 Precision *prec = new Precision;
 353                 prec->precision = default_prec;
 354                 prec->type = type->name;
 355                 stage->content.body.insert(insert_point, prec);
 356
 357                 have_default.insert(type->name);
 358         }
 359 }
 360
 361
 362 void FeatureConverter::apply(Stage &s, const Features &feat)
 363 {
 364         stage = &s;
 365         features = feat;
 366
 367         if(!stage->required_features.glsl_version)
 368                 stage->required_features.glsl_version = Version(1, (stage->required_features.target_api==OPENGL_ES ? 0 : 10));
 369
 370         apply();
 371 }
 372
 373 void FeatureConverter::unsupported(const string &reason)
 374 {
 375         Diagnostic diagnostic;
 376         diagnostic.severity = Diagnostic::ERR;
 377         diagnostic.source = GENERATED_SOURCE;
 378         diagnostic.line = 0;
 379         diagnostic.message = reason;
 380         stage->diagnostics.push_back(diagnostic);
 381 }
 382
 383 bool FeatureConverter::check_version(const Version &feature_version) const
 384 {
 385         if(features.glsl_version<feature_version)
 386                 return false;
 387         else if(stage->required_features.glsl_version<feature_version)
 388                 stage->required_features.glsl_version = feature_version;
 389
 390         return true;
 391 }
 392
 393 bool FeatureConverter::check_extension(bool Features::*extension) const
 394 {
 395         if(!(features.*extension))
 396                 return false;
 397
 398         stage->required_features.*extension = true;
 399
 400         return true;
 401 }
 402
 403
 404 void StructuralFeatureConverter::apply()
 405 {
 406         if(supports_stage(stage->type))
 407         {
 408                 stage->content.visit(*this);
 409                 NodeRemover().apply(*stage, nodes_to_remove);
 410         }
 411         else
 412                 unsupported(format("Stage %s is not supported", Stage::get_stage_name(stage->type)));
 413 }
 414
 415 void StructuralFeatureConverter::visit(Block &block)
 416 {
 417         for(auto i=block.body.begin(); i!=block.body.end(); ++i)
 418         {
 419                 if(&block==&stage->content)
 420                         uniform_insert_point = i;
 421                 (*i)->visit(*this);
 422         }
 423 }
 424
 425 void StructuralFeatureConverter::visit(RefPtr<Expression> &expr)
 426 {
 427         r_replaced_reference = 0;
 428         expr->visit(*this);
 429         if(r_replaced_reference)
 430                 expr = r_replaced_reference;
 431         r_replaced_reference = 0;
 432 }
 433
 434 bool StructuralFeatureConverter::supports_stage(Stage::Type st) const
 435 {
 436         if(st==Stage::GEOMETRY)
 437         {
 438                 if(features.target_api==OPENGL_ES)
 439                         return check_version(Version(3, 20));
 440                 else
 441                         return check_version(Version(1, 50));
 442         }
 443         else
 444                 return true;
 445 }
 446
 447 bool StructuralFeatureConverter::supports_unified_interface_syntax() const
 448 {
 449         if(features.target_api==OPENGL_ES)
 450                 return check_version(Version(3, 0));
 451         else
 452                 return check_version(Version(1, 30));
 453 }
 454
 455 void StructuralFeatureConverter::visit(VariableReference &var)
 456 {
 457         if(var.declaration==frag_out && !supports_unified_interface_syntax())
 458         {
 459                 var.name = "gl_FragColor";
 460                 var.declaration = 0;
 461         }
 462
 463         r_flattened_interface = nodes_to_remove.count(var.declaration);
 464 }
 465
 466 void StructuralFeatureConverter::visit(MemberAccess &memacc)
 467 {
 468         r_flattened_interface = false;
 469         visit(memacc.left);
 470         if(r_flattened_interface)
 471         {
 472                 VariableReference *var = new VariableReference;
 473                 var->name = memacc.member;
 474                 r_replaced_reference = var;
 475         }
 476 }
 477
 478 void StructuralFeatureConverter::visit(Assignment &assign)
 479 {
 480         TraversingVisitor::visit(assign);
 481         if(assign.target.declaration==frag_out && !supports_unified_interface_syntax())
 482                 assign.target.declaration = 0;
 483 }
 484
 485 bool StructuralFeatureConverter::supports_unified_sampling_functions() const
 486 {
 487         if(features.target_api==OPENGL_ES)
 488                 return check_version(Version(3, 0));
 489         else
 490                 return check_version(Version(1, 30));
 491 }
 492
 493 void StructuralFeatureConverter::visit(FunctionCall &call)
 494 {
 495         if(call.declaration && call.declaration->source==BUILTIN_SOURCE)
 496         {
 497                 if(!call.name.compare(0, 7, "texture") && call.arguments.size()>=1)
 498                 {
 499                         const ImageTypeDeclaration *arg_image = dynamic_cast<const ImageTypeDeclaration *>(call.arguments.front()->type);
 500                         if(arg_image && !supports_unified_sampling_functions())
 501                         {
 502                                 string suffix = call.name.substr(7);
 503                                 call.name = (arg_image->shadow ? "shadow" : "texture");
 504
 505                                 switch(arg_image->dimensions)
 506                                 {
 507                                 case ImageTypeDeclaration::ONE: call.name += "1D"; break;
 508                                 case ImageTypeDeclaration::TWO: call.name += "2D"; break;
 509                                 case ImageTypeDeclaration::THREE: call.name += "3D"; break;
 510                                 case ImageTypeDeclaration::CUBE: call.name += "Cube"; break;
 511                                 }
 512
 513                                 if(arg_image->array)
 514                                 {
 515                                         /* Array textures and the unified sampling function name were
 516                                         both introduced in GLSL 1.30. */
 517                                         if(arg_image->dimensions==ImageTypeDeclaration::ONE || arg_image->dimensions==ImageTypeDeclaration::TWO)
 518                                                 check_extension(&Features::ext_texture_array);
 519                                         call.name += "Array";
 520                                 }
 521
 522                                 call.name += suffix;
 523                         }
 524                 }
 525         }
 526
 527         TraversingVisitor::visit(call);
 528 }
 529
 530 bool StructuralFeatureConverter::supports_interface_blocks(const string &iface) const
 531 {
 532         if(features.target_api==OPENGL_ES)
 533         {
 534                 if(iface=="uniform")
 535                         return check_version(Version(3, 0));
 536                 else
 537                         return check_version(Version(3, 20));
 538         }
 539         else if(check_version(Version(1, 50)))
 540                 return true;
 541         else if(iface=="uniform")
 542                 return check_extension(&Features::arb_uniform_buffer_object);
 543         else
 544                 return false;
 545 }
 546
 547 void StructuralFeatureConverter::visit(VariableDeclaration &var)
 548 {
 549         if(var.block_declaration)
 550         {
 551                 bool push_constant = has_layout_qualifier(var.layout.get(), "push_constant");
 552                 if(!supports_interface_blocks(var.interface) || (push_constant && features.target_api!=VULKAN))
 553                 {
 554                         if(var.name.find(' ')==string::npos)
 555                                 unsupported("ARB_uniform_buffer_object required for interface block instances");
 556                         else
 557                         {
 558                                 for(const RefPtr<Statement> &s: var.block_declaration->members.body)
 559                                         if(VariableDeclaration *mem = dynamic_cast<VariableDeclaration *>(s.get()))
 560                                                 mem->interface = var.interface;
 561                                 stage->content.body.splice(uniform_insert_point, var.block_declaration->members.body);
 562                                 nodes_to_remove.insert(&var);
 563                                 nodes_to_remove.insert(var.block_declaration);
 564                         }
 565                 }
 566         }
 567
 568         if((var.interface=="in" || var.interface=="out") && !supports_unified_interface_syntax())
 569                 if(stage->type==Stage::FRAGMENT && var.interface=="out")
 570                 {
 571                         frag_out = &var;
 572                         nodes_to_remove.insert(&var);
 573                 }
 574
 575         TraversingVisitor::visit(var);
 576 }
 577
 578
 579 void QualifierConverter::apply()
 580 {
 581         stage->content.visit(*this);
 582 }
 583
 584 bool QualifierConverter::supports_interface_layouts() const
 585 {
 586         if(features.target_api==OPENGL_ES)
 587                 return check_version(Version(3, 0));
 588         else if(check_version(Version(3, 30)))
 589                 return true;
 590         else if(check_version(Version(1, 30)))
 591                 return check_extension(&Features::arb_explicit_attrib_location);
 592         else
 593                 return false;
 594 }
 595
 596 bool QualifierConverter::supports_stage_interface_layouts() const
 597 {
 598         if(features.target_api==OPENGL_ES)
 599                 return check_version(Version(3, 10));
 600         else if(check_version(Version(4, 10)))
 601                 return true;
 602         else
 603                 return check_extension(&Features::arb_separate_shader_objects);
 604 }
 605
 606 bool QualifierConverter::supports_centroid_sampling() const
 607 {
 608         if(features.target_api==OPENGL_ES)
 609                 return check_version(Version(3, 0));
 610         else if(check_version(Version(1, 20)))
 611                 return true;
 612         else
 613                 return check_extension(&Features::ext_gpu_shader4);
 614 }
 615
 616 bool QualifierConverter::supports_sample_sampling() const
 617 {
 618         if(features.target_api==OPENGL_ES)
 619                 return check_version(Version(3, 20));
 620         else if(check_version(Version(4, 0)))
 621                 return true;
 622         else
 623                 return check_extension(&Features::arb_gpu_shader5);
 624 }
 625
 626 bool QualifierConverter::supports_uniform_location() const
 627 {
 628         if(features.target_api==OPENGL_ES)
 629                 return check_version(Version(3, 10));
 630         else if(check_version(Version(4, 30)))
 631                 return true;
 632         else
 633                 return check_extension(&Features::arb_explicit_uniform_location);
 634 }
 635
 636 bool QualifierConverter::supports_binding() const
 637 {
 638         if(features.target_api==OPENGL_ES)
 639                 return check_version(Version(3, 10));
 640         else
 641                 return check_version(Version(4, 20));
 642 }
 643
 644 bool QualifierConverter::supports_interface_block_location() const
 645 {
 646         if(features.target_api==OPENGL_ES)
 647                 return check_version(Version(3, 20));
 648         else if(check_version(Version(4, 40)))
 649                 return true;
 650         else
 651                 return check_extension(&Features::arb_enhanced_layouts);
 652 }
 653
 654 void QualifierConverter::visit(VariableDeclaration &var)
 655 {
 656         if(var.layout)
 657         {
 658                 for(auto i=var.layout->qualifiers.begin(); i!=var.layout->qualifiers.end(); )
 659                 {
 660                         if(i->name=="location")
 661                         {
 662                                 bool supported = true;
 663                                 bool external = false;
 664                                 if(var.block_declaration)
 665                                         supported = supports_interface_block_location();
 666                                 else if(var.interface=="in")
 667                                 {
 668                                         external = (stage->type==Stage::VERTEX);
 669                                         supported = (external ? supports_interface_layouts() : supports_stage_interface_layouts());
 670                                 }
 671                                 else if(var.interface=="out")
 672                                 {
 673                                         external = (stage->type==Stage::FRAGMENT);
 674                                         supported = (external ? supports_interface_layouts() : supports_stage_interface_layouts());
 675                                         if(external && !supported && !check_extension(&Features::ext_gpu_shader4))
 676                                         {
 677                                                 external = false;
 678                                                 if(i->value!=0)
 679                                                         unsupported("EXT_gpu_shader4 required for multiple fragment shader outputs");
 680                                         }
 681                                 }
 682                                 else if(var.interface=="uniform")
 683                                         supported = supports_uniform_location();
 684
 685                                 if(!supported)
 686                                 {
 687                                         if(external)
 688                                                 stage->locations[var.name] = i->value;
 689                                         i = var.layout->qualifiers.erase(i);
 690                                 }
 691                                 else
 692                                         ++i;
 693                         }
 694                         else if(i->name=="binding" && !supports_binding())
 695                         {
 696                                 if(var.block_declaration)
 697                                         stage->uniform_block_bindings[var.block_declaration->block_name] = i->value;
 698                                 else if(dynamic_cast<const ImageTypeDeclaration *>(get_ultimate_base_type(var.type_declaration)))
 699                                         stage->texture_bindings[var.name] = i->value;
 700
 701                                 i = var.layout->qualifiers.erase(i);
 702                         }
 703                         else
 704                                 ++i;
 705                 }
 706
 707                 if(var.layout->qualifiers.empty())
 708                         var.layout = 0;
 709         }
 710
 711         if(var.sampling=="centroid")
 712         {
 713                 if(!supports_centroid_sampling())
 714                         var.sampling = string();
 715         }
 716         else if(var.sampling=="sample")
 717         {
 718                 if(!supports_sample_sampling())
 719                         var.sampling = string();
 720         }
 721
 722         if(var.name=="gl_ClipDistance")
 723                 if(const Literal *literal_size = dynamic_cast<const Literal *>(var.array_size.get()))
 724                         stage->n_clip_distances = literal_size->value.value<int>();
 725
 726         TraversingVisitor::visit(var);
 727 }
 728
 729 } // namespace SL
 730 } // namespace GL
 731 } // namespace Msp