[Impeller Scene] Refactor Nodes/Meshes for simplicity and GLTF compatibility (flutter#38180)

Author: bdero

ci/licenses_golden/licenses_flutter

@@ -1662,19 +1662,19 @@ FILE: ../../../flutter/impeller/scene/importer/vertices_builder.cc
 FILE: ../../../flutter/impeller/scene/importer/vertices_builder.h
 FILE: ../../../flutter/impeller/scene/material.cc
 FILE: ../../../flutter/impeller/scene/material.h
+FILE: ../../../flutter/impeller/scene/mesh.cc
+FILE: ../../../flutter/impeller/scene/mesh.h
+FILE: ../../../flutter/impeller/scene/node.cc
+FILE: ../../../flutter/impeller/scene/node.h
 FILE: ../../../flutter/impeller/scene/scene.cc
 FILE: ../../../flutter/impeller/scene/scene.h
 FILE: ../../../flutter/impeller/scene/scene_context.cc
 FILE: ../../../flutter/impeller/scene/scene_context.h
 FILE: ../../../flutter/impeller/scene/scene_encoder.cc
 FILE: ../../../flutter/impeller/scene/scene_encoder.h
-FILE: ../../../flutter/impeller/scene/scene_entity.cc
-FILE: ../../../flutter/impeller/scene/scene_entity.h
 FILE: ../../../flutter/impeller/scene/scene_unittests.cc
 FILE: ../../../flutter/impeller/scene/shaders/geometry.vert
 FILE: ../../../flutter/impeller/scene/shaders/unlit.frag
-FILE: ../../../flutter/impeller/scene/static_mesh_entity.cc
-FILE: ../../../flutter/impeller/scene/static_mesh_entity.h
 FILE: ../../../flutter/impeller/tessellator/c/tessellator.cc
 FILE: ../../../flutter/impeller/tessellator/c/tessellator.h
 FILE: ../../../flutter/impeller/tessellator/dart/lib/tessellator.dart

impeller/scene/BUILD.gn

@@ -12,16 +12,16 @@ impeller_component("scene") {
     "geometry.h",
     "material.cc",
     "material.h",
+    "mesh.cc",
+    "mesh.h",
+    "node.cc",
+    "node.h",
     "scene.cc",
     "scene.h",
     "scene_context.cc",
     "scene_context.h",
     "scene_encoder.cc",
     "scene_encoder.h",
-    "scene_entity.cc",
-    "scene_entity.h",
-    "static_mesh_entity.cc",
-    "static_mesh_entity.h",
   ]
 
   public_deps = [

impeller/scene/README.md

@@ -43,54 +43,52 @@ run_action.SetLoop(impeller::scene::AnimationAction::kLoopForever);
 run_action.SetWeight(0.3f);
 run_action.Play();
 
-scene.Add(
+scene.GetRoot().AddChild(
     impeller::scene::DirectionalLight(
         /* color */ impeller::Color::AntiqueWhite(),
         /* intensity */ 5,
         /* direction */ {2, 3, 4}));
 
-impeller::scene::StaticMeshEntity sphere_entity;
-sphere_entity.SetGlobalTransform(
+Node sphere_node;
+Mesh sphere_mesh;
+sphere_node.SetGlobalTransform(
     Matrix::MakeRotationEuler({kPiOver4, kPiOver4, 0}));
-sphere_entity.SetCullingMode(impeller::scene::CullingMode::kFrustum);
 
-std::unique_ptr<impeller::scene::SphereGeometry> sphere =
+auto sphere_geometry =
     impeller::scene::Geometry::MakeSphere(allocator, /* radius */ 2);
 
-sphere_entity.SetGeometry(sphere);
-
 auto material = impeller::scene::Material::MakeStandard();
-material.SetAlbedo(impeller::Color::Red());
-material.SetRoughness(0.4);
-material.SetMetallic(0.2);
+material->SetAlbedo(impeller::Color::Red());
+material->SetRoughness(0.4);
+material->SetMetallic(0.2);
 // Common properties shared by all materials.
-material.SetEnvironmentMap(environment_hdri);
-material.SetFlatShaded(true);
-material.SetBlendConfig({
+material->SetEnvironmentMap(environment_hdri);
+material->SetFlatShaded(true);
+material->SetBlendConfig({
   impeller::BlendOperation::kAdd,               // color_op
   impeller::BlendFactor::kOne,                  // source_color_factor
   impeller::BlendFactor::kOneMinusSourceAlpha,  // destination_color_factor
   impeller::BlendOperation::kAdd,               // alpha_op
   impeller::BlendFactor::kOne,                  // source_alpha_factor
   impeller::BlendFactor::kOneMinusSourceAlpha,  // destination_alpha_factor
 });
-material.SetStencilConfig({
+material->SetStencilConfig({
   impeller::StencilOperation::kIncrementClamp,  // operation
   impeller::CompareFunction::kAlways,           // compare
 });
-
-sphere_entity->SetMaterials({material});
-
-
-impeller::scene::StaticMeshEntity cube_entity;
-cube_entity.GetGeometry(
-    impeller::scene::Geometry::MakeCube(allocator, {4, 4, 4}));
-cube_entity.SetMaterials({material});
-
-cube_entity.SetLocalTransform(Matrix::MakeTranslation({4, 0, 0}));
-
-sphere_entity->Add(sube_entity);
-scene.Add(sphere_entity);
+sphere_mesh.AddPrimitive({sphere_geometry, material});
+sphere_node.SetMesh(sphere_mesh);
+
+Node cube_node;
+cube_node.SetLocalTransform(Matrix::MakeTranslation({4, 0, 0}));
+Mesh cube_mesh;
+auto cube_geometry = impeller::scene::Geometry::MakeCuboid(
+    allocator, {4, 4, 4});
+cube_mesh.AddPrimitive({cube_geometry, material});
+cube_node.SetMesh(cube_mesh);
+
+sphere_node.AddChild(cube_node);
+scene.GetRoot().AddChild(sphere_node);
 
 /// Post processing.
 

impeller/scene/geometry.cc

@@ -40,15 +40,15 @@ std::shared_ptr<VertexBufferGeometry> Geometry::MakeVertexBuffer(
   return result;
 }
 
-std::shared_ptr<VertexBufferGeometry> Geometry::MakeFromFBMesh(
-    const fb::StaticMesh& mesh,
+std::shared_ptr<VertexBufferGeometry> Geometry::MakeFromFBMeshPrimitive(
+    const fb::MeshPrimitive& mesh,
     Allocator& allocator) {
   IndexType index_type;
   switch (mesh.indices()->type()) {
-    case fb::IndicesType::k16Bit:
+    case fb::IndexType::k16Bit:
       index_type = IndexType::k16bit;
       break;
-    case fb::IndicesType::k32Bit:
+    case fb::IndexType::k32Bit:
       index_type = IndexType::k32bit;
       break;
   }

impeller/scene/geometry.h

@@ -28,8 +28,8 @@ class Geometry {
   static std::shared_ptr<VertexBufferGeometry> MakeVertexBuffer(
       VertexBuffer vertex_buffer);
 
-  static std::shared_ptr<VertexBufferGeometry> MakeFromFBMesh(
-      const fb::StaticMesh& mesh,
+  static std::shared_ptr<VertexBufferGeometry> MakeFromFBMeshPrimitive(
+      const fb::MeshPrimitive& mesh,
       Allocator& allocator);
 
   virtual VertexBuffer GetVertexBuffer(Allocator& allocator) const = 0;

impeller/scene/importer/importer_gltf.cc

@@ -33,9 +33,9 @@ static bool WithinRange(int index, size_t size) {
   return index >= 0 && static_cast<size_t>(index) < size;
 }
 
-static bool ProcessStaticMesh(const tinygltf::Model& gltf,
-                              const tinygltf::Primitive& primitive,
-                              fb::StaticMeshT& static_mesh) {
+static bool ProcessMeshPrimitive(const tinygltf::Model& gltf,
+                                 const tinygltf::Primitive& primitive,
+                                 fb::MeshPrimitiveT& mesh_primitive) {
   //---------------------------------------------------------------------------
   /// Vertices.
   ///
@@ -93,7 +93,7 @@ static bool ProcessStaticMesh(const tinygltf::Model& gltf,
                                      accessor.count);            // count
     }
 
-    builder.WriteFBVertices(static_mesh.vertices);
+    builder.WriteFBVertices(mesh_primitive.vertices);
   }
 
   //---------------------------------------------------------------------------
@@ -112,10 +112,10 @@ static bool ProcessStaticMesh(const tinygltf::Model& gltf,
 
   switch (index_accessor.componentType) {
     case TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT:
-      indices->type = fb::IndicesType::k16Bit;
+      indices->type = fb::IndexType::k16Bit;
       break;
     case TINYGLTF_COMPONENT_TYPE_UNSIGNED_INT:
-      indices->type = fb::IndicesType::k32Bit;
+      indices->type = fb::IndexType::k32Bit;
       break;
     default:
       std::cerr << "Mesh primitive has unsupported index type "
@@ -128,7 +128,7 @@ static bool ProcessStaticMesh(const tinygltf::Model& gltf,
       &gltf.buffers[index_view.buffer].data[index_view.byteOffset];
   std::memcpy(indices->data.data(), index_buffer, indices->data.size());
 
-  static_mesh.indices = std::move(indices);
+  mesh_primitive.indices = std::move(indices);
 
   return true;
 }
@@ -177,11 +177,11 @@ static void ProcessNode(const tinygltf::Model& gltf,
   if (WithinRange(in_node.mesh, gltf.meshes.size())) {
     auto& mesh = gltf.meshes[in_node.mesh];
     for (const auto& primitive : mesh.primitives) {
-      auto static_mesh = std::make_unique<fb::StaticMeshT>();
-      if (!ProcessStaticMesh(gltf, primitive, *static_mesh)) {
+      auto mesh_primitive = std::make_unique<fb::MeshPrimitiveT>();
+      if (!ProcessMeshPrimitive(gltf, primitive, *mesh_primitive)) {
         continue;
       }
-      out_node.meshes.push_back(std::move(static_mesh));
+      out_node.mesh_primitives.push_back(std::move(mesh_primitive));
     }
   }
 

impeller/scene/importer/importer_unittests.cc

@@ -26,8 +26,8 @@ TEST(ImporterTest, CanParseGLTF) {
   Matrix node_transform = ToMatrix(*node.transform);
   ASSERT_MATRIX_NEAR(node_transform, Matrix());
 
-  ASSERT_EQ(node.meshes.size(), 1u);
-  auto& mesh = *node.meshes[0];
+  ASSERT_EQ(node.mesh_primitives.size(), 1u);
+  auto& mesh = *node.mesh_primitives[0];
   ASSERT_EQ(mesh.indices->count, 918u);
 
   uint16_t first_index =

impeller/scene/importer/scene.fbs

@@ -43,15 +43,15 @@ struct Vertex {
   color: Color;
 }
 
-enum IndicesType:byte {
+enum IndexType:byte {
   k16Bit,
   k32Bit,
 }
 
 table Indices {
   data: [ubyte];
   count: uint32;
-  type: IndicesType;
+  type: IndexType;
 }
 
 table Texture {
@@ -65,7 +65,7 @@ table Material {
   // TODO(bdero): PBR textures.
 }
 
-table StaticMesh {
+table MeshPrimitive {
   vertices: [Vertex];
   indices: Indices;
   material: Material;
@@ -74,7 +74,7 @@ table StaticMesh {
 table Node {
   children: [Node];
   transform: Matrix;
-  meshes: [StaticMesh];
+  mesh_primitives: [MeshPrimitive];
 }
 
 table Scene {

impeller/scene/mesh.cc

@@ -0,0 +1,44 @@
+// 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 "impeller/scene/mesh.h"
+
+#include <memory>
+
+#include "impeller/base/validation.h"
+#include "impeller/scene/material.h"
+#include "impeller/scene/scene_encoder.h"
+
+namespace impeller {
+namespace scene {
+
+Mesh::Mesh() = default;
+Mesh::~Mesh() = default;
+
+void Mesh::AddPrimitive(Primitive mesh) {
+  if (mesh.geometry_ == nullptr) {
+    VALIDATION_LOG << "Mesh geometry cannot be null.";
+  }
+  if (mesh.material_ == nullptr) {
+    VALIDATION_LOG << "Mesh material cannot be null.";
+  }
+
+  meshes_.push_back(std::move(mesh));
+}
+
+bool Mesh::Render(SceneEncoder& encoder, const Matrix& transform) const {
+  for (const auto& mesh : meshes_) {
+    SceneCommand command = {
+        .label = "Mesh Primitive",
+        .transform = transform,
+        .geometry = mesh.geometry_.get(),
+        .material = mesh.material_.get(),
+    };
+    encoder.Add(command);
+  }
+  return true;
+}
+
+}  // namespace scene
+}  // namespace impeller

impeller/scene/mesh.h

@@ -0,0 +1,37 @@
+// 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 <memory>
+#include <type_traits>
+
+#include "flutter/fml/macros.h"
+#include "impeller/scene/geometry.h"
+#include "impeller/scene/material.h"
+#include "impeller/scene/scene_encoder.h"
+
+namespace impeller {
+namespace scene {
+
+class Mesh final {
+ public:
+  struct Primitive {
+    std::shared_ptr<Geometry> geometry_;
+    std::shared_ptr<Material> material_;
+  };
+
+  Mesh();
+  ~Mesh();
+
+  void AddPrimitive(Primitive mesh_);
+
+  bool Render(SceneEncoder& encoder, const Matrix& transform) const;
+
+ private:
+  std::vector<Primitive> meshes_;
+};
+
+}  // namespace scene
+}  // namespace impeller