Wire up GLSL to spirv compiler.

engine/src/flutter/impeller/compiler/BUILD.gn

@@ -5,7 +5,11 @@
 executable("compiler") {
   output_name = "impellerc"
 
-  sources = [ "impellerc_main.cc" ]
+  sources = [
+    "compiler.cc",
+    "compiler.h",
+    "impellerc_main.cc",
+  ]
 
   deps = [
     "//flutter/fml",

engine/src/flutter/impeller/compiler/compiler.cc

@@ -0,0 +1,84 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/impeller/compiler/compiler.h"
+
+#include <memory>
+
+namespace impeller {
+namespace compiler {
+
+class Includer final : public shaderc::CompileOptions::IncluderInterface {
+ public:
+  Includer() = default;
+
+  // |shaderc::CompileOptions::IncluderInterface|
+  ~Includer() override = default;
+
+  // |shaderc::CompileOptions::IncluderInterface|
+  shaderc_include_result* GetInclude(const char* requested_source,
+                                     shaderc_include_type type,
+                                     const char* requesting_source,
+                                     size_t include_depth) override {
+    return nullptr;
+  }
+
+  // |shaderc::CompileOptions::IncluderInterface|
+  void ReleaseInclude(shaderc_include_result* data) override {}
+
+ private:
+  FML_DISALLOW_COPY_AND_ASSIGN(Includer);
+};
+
+static shaderc_shader_kind ToShaderCShaderKind(Compiler::SourceType type) {
+  switch (type) {
+    case Compiler::SourceType::kVertexShader:
+      return shaderc_shader_kind::shaderc_vertex_shader;
+    case Compiler::SourceType::kFragmentShader:
+      return shaderc_shader_kind::shaderc_fragment_shader;
+  }
+  return shaderc_shader_kind::shaderc_vertex_shader;
+}
+
+Compiler::Compiler(const fml::Mapping& source_mapping,
+                   SourceOptions source_options) {
+  if (source_mapping.GetMapping() == nullptr) {
+    return;
+  }
+
+  shaderc::CompileOptions options;
+  options.SetGenerateDebugInfo();
+  options.SetOptimizationLevel(
+      shaderc_optimization_level::shaderc_optimization_level_size);
+  options.SetSourceLanguage(
+      shaderc_source_language::shaderc_source_language_glsl);
+  options.SetTargetEnvironment(
+      shaderc_target_env::shaderc_target_env_vulkan,
+      shaderc_env_version::shaderc_env_version_opengl_4_5);
+  options.SetTargetSpirv(shaderc_spirv_version::shaderc_spirv_version_1_3);
+  options.SetAutoBindUniforms(true);
+  options.SetAutoMapLocations(true);
+  options.SetIncluder(std::make_unique<Includer>());
+
+  shaderc::Compiler compiler;
+  if (!compiler.IsValid()) {
+    return;
+  }
+
+  result_ = compiler.CompileGlslToSpv(
+      reinterpret_cast<const char*>(
+          source_mapping.GetMapping()),          // source_text
+      source_mapping.GetSize(),                  // source_text_size
+      ToShaderCShaderKind(source_options.type),  // shader_kind
+      source_options.file_name.c_str(),          // input_file_name
+      source_options.entry_point_name.c_str(),   // entry_point_name
+      options                                    // options
+  );
+  is_valid_ = true;
+}
+
+Compiler::~Compiler() = default;
+
+}  // namespace compiler
+}  // namespace impeller

engine/src/flutter/impeller/compiler/compiler.h

@@ -0,0 +1,45 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#pragma once
+
+#include <string>
+
+#include "flutter/fml/macros.h"
+#include "flutter/fml/mapping.h"
+#include "shaderc/shaderc.hpp"
+
+namespace impeller {
+namespace compiler {
+
+class Compiler {
+ public:
+  enum class SourceType {
+    kVertexShader,
+    kFragmentShader,
+  };
+
+  static SourceType SourceTypeFromFileName(const std::string& file_name);
+
+  struct SourceOptions {
+    SourceType type = SourceType::kVertexShader;
+    std::string file_name = "main.glsl";
+    std::string entry_point_name = "main";
+  };
+
+  Compiler(const fml::Mapping& source_mapping, SourceOptions options);
+
+  ~Compiler();
+
+  bool IsValid() const;
+
+ private:
+  shaderc::SpvCompilationResult result_;
+  bool is_valid_ = false;
+
+  FML_DISALLOW_COPY_AND_ASSIGN(Compiler);
+};
+
+}  // namespace compiler
+}  // namespace impeller

engine/src/flutter/impeller/compiler/fixtures/sample.frag

@@ -0,0 +1,23 @@
+#version 450
+
+struct Hello {
+  vec4 stuff;
+  vec2 more_stuff;
+  float dunno;
+};
+
+uniform Uniforms {
+  Hello myHello;
+  vec4 hi;
+  Hello goodbyeHello;
+};
+
+uniform sampler2D textureSampler;
+
+in vec2 inTextureCoord;
+
+out vec4 outColor;
+
+void main() {
+  outColor = texture(textureSampler, inTextureCoord * myHello.more_stuff);
+}