From 1867ab94c4aab81effb27680cd34c79cd33dd977 Mon Sep 17 00:00:00 2001
From: magicianA <xiehaochen.ava@bytedance.com>
Date: Fri, 22 Jul 2022 02:37:04 +0800
Subject: [PATCH] [Impeller] Generate descriptor set layout bindings in
 generated C++ headers. (flutter/engine#34779)

---
 .../impeller/compiler/code_gen_template.h     | 28 +++++++++++++++++++
 .../flutter/impeller/compiler/reflector.cc    | 26 +++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/engine/src/flutter/impeller/compiler/code_gen_template.h b/engine/src/flutter/impeller/compiler/code_gen_template.h
index c408dc737a3..4a061fcadb5 100644
--- a/engine/src/flutter/impeller/compiler/code_gen_template.h
+++ b/engine/src/flutter/impeller/compiler/code_gen_template.h
@@ -147,6 +147,34 @@ std::move({{ arg.argument_name }}){% if not loop.is_last %}, {% endif %}
 
 {% endfor %}
 
+  // ===========================================================================
+  // Metadata for Vulkan =======================================================
+  // ===========================================================================
+#ifdef IMPELLER_ENABLE_VULKAN_REFLECTION
+{% if length(buffers)+length(sampled_images) > 0 %}
+  static constexpr std::array<VkDescriptorSetLayoutBinding,{{length(buffers)+length(sampled_images)}}> kDescriptorSetLayouts{
+{% for buffer in buffers %}
+    VkDescriptorSetLayoutBinding{
+      {{buffer.binding}}, // binding = {{buffer.binding}}
+      VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, // descriptorType = Uniform Buffer
+      1, // descriptorCount = 1
+      {{to_vk_shader_stage_flag_bits(shader_stage)}}, // stageFlags = {{to_shader_stage(shader_stage)}}
+      nullptr, // pImmutableSamplers = NULL
+    },
+{% endfor %}
+{% for sampled_image in sampled_images %}
+    VkDescriptorSetLayoutBinding{
+      {{sampled_image.binding}}, // binding = {{sampled_image.binding}}
+      VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE, // descriptorType = Sampled Image
+      1, // descriptorCount = 1
+      {{to_vk_shader_stage_flag_bits(shader_stage)}},// stageFlags = {{to_shader_stage(shader_stage)}}
+      nullptr, // pImmutableSamplers = NULL
+    },
+{% endfor %}
+  };
+{% endif %}
+#endif
+
 };  // struct {{camel_case(shader_name)}}{{camel_case(shader_stage)}}Shader
 
 }  // namespace impeller
diff --git a/engine/src/flutter/impeller/compiler/reflector.cc b/engine/src/flutter/impeller/compiler/reflector.cc
index ae0f294bb3e..69d61719e08 100644
--- a/engine/src/flutter/impeller/compiler/reflector.cc
+++ b/engine/src/flutter/impeller/compiler/reflector.cc
@@ -108,6 +108,28 @@ static std::string StringToShaderStage(std::string str) {
   return "ShaderStage::kUnknown";
 }
 
+static std::string StringToVkShaderStage(std::string str) {
+  if (str == "vertex") {
+    return "VK_SHADER_STAGE_VERTEX_BIT";
+  }
+  if (str == "fragment") {
+    return "VK_SHADER_STAGE_FRAGMENT_BIT";
+  }
+
+  if (str == "tessellation_control") {
+    return "VK_SHADER_STAGE_TESSELLATION_CONTROL_BIT";
+  }
+
+  if (str == "tessellation_evaluation") {
+    return "VK_SHADER_STAGE_TESSELLATION_EVALUATION_BIT";
+  }
+
+  if (str == "compute") {
+    return "VK_SHADER_STAGE_COMPUTE_BIT";
+  }
+  return "VK_SHADER_STAGE_ALL_GRAPHICS";
+}
+
 Reflector::Reflector(Options options,
                      std::shared_ptr<const spirv_cross::ParsedIR> ir,
                      std::shared_ptr<fml::Mapping> shader_data,
@@ -367,6 +389,10 @@ std::shared_ptr<fml::Mapping> Reflector::InflateTemplate(
                    [type = compiler_.GetType()](inja::Arguments& args) {
                      return ToString(type);
                    });
+  env.add_callback(
+      "to_vk_shader_stage_flag_bits", 1u, [](inja::Arguments& args) {
+        return StringToVkShaderStage(args.at(0u)->get<std::string>());
+      });
 
   auto inflated_template =
       std::make_shared<std::string>(env.render(tmpl, *template_arguments_));