Implementing glTF 1.0 parser

chrome/browser/android/vr_shell/gltf_asset.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_ANDROID_VR_SHELL_GLTF_ASSET_H_
+#define CHROME_BROWSER_ANDROID_VR_SHELL_GLTF_ASSET_H_
+
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "ui/gl/gl_bindings.h"
+
+namespace vr_shell {
+
+namespace gltf {
+
+enum Type {
+  UNKNOWN = 0,
+  SCALAR,
+  VEC2,
+  VEC3,
+  VEC4,
+  MAT2,
+  MAT3,
+  MAT4,
+};
+
+Type GetType(const std::string& type);
+
+// A Buffer is data stored as binary blob in little-endian format.
+using Buffer = std::string;
+
+// The following structures match the objects defined in glTF 1.0 standard.
+// https://github.com/KhronosGroup/glTF/tree/master/specification/1.0#properties-reference
+
+// A BufferView is subset of data in a buffer.
+struct BufferView {
+  const Buffer* buffer;
+  int byte_length = 0;
+  int byte_offset;
+  int target = GL_ARRAY_BUFFER;
+};
+
+// An Accessor is a typed view into a BufferView.
+struct Accessor {
+  const BufferView* buffer_view;
+  int byte_offset;
+  // TODO(acondor): byte_stride is on BufferView in glTF 2.0.
+  int byte_stride = 0;
+  int component_type;
+  int count;
+  Type type;
+};
+
+// A Mesh is a set of primitives to be rendered.
+struct Mesh {
+  // A Primitive describes a geometry to be rendered.
+  struct Primitive {
+    std::map<std::string, const Accessor*> attributes;
+    const Accessor* indices;
+    int mode;
+    Primitive();
+    ~Primitive();
+  };
+
+  std::vector<std::unique_ptr<Primitive>> primitives;
+  Mesh();
+  ~Mesh();
+};
+
+// A Node in the node hierarchy.
+struct Node {
+  std::vector<const Node*> children;
+  // TODO(acondor): There is only one mesh per node in glTF 2.0.
+  std::vector<const Mesh*> meshes;
+  Node();
+  ~Node();
+};
+
+// The root nodes of a scene.
+struct Scene {
+  std::vector<const Node*> nodes;
+  Scene();
+  ~Scene();
+};
+
+class Asset {
+ public:
+  Asset();
+  virtual ~Asset();
+
+  std::size_t AddBuffer(std::unique_ptr<Buffer> buffer);
+  std::size_t AddBufferView(std::unique_ptr<BufferView> buffer_view);
+  std::size_t AddAccessor(std::unique_ptr<Accessor> accessor);
+  std::size_t AddMesh(std::unique_ptr<Mesh> mesh);
+  std::size_t AddNode(std::unique_ptr<Node> node);
+  std::size_t AddScene(std::unique_ptr<Scene> scene);
+  const Buffer* GetBuffer(std::size_t id) const;
+  const BufferView* GetBufferView(std::size_t id) const;
+  const Accessor* GetAccessor(std::size_t id) const;
+  const Mesh* GetMesh(std::size_t id) const;
+  const Node* GetNode(std::size_t id) const;
+  const Scene* GetScene(std::size_t id) const;
+
+  const Scene* GetMainScene() const { return scene_; }
+
+  void SetMainScene(const Scene* scene) { scene_ = scene; }
+
+ private:
+  std::vector<std::unique_ptr<Buffer>> buffers_;
+  std::vector<std::unique_ptr<BufferView>> buffer_views_;
+  std::vector<std::unique_ptr<Accessor>> accessors_;
+  std::vector<std::unique_ptr<Mesh>> meshes_;
+  std::vector<std::unique_ptr<Node>> nodes_;
+  std::vector<std::unique_ptr<Scene>> scenes_;
+  const Scene* scene_;
+};
+
+}  // namespace gltf
+
+}  // namespace vr_shell
+
+#endif  // CHROME_BROWSER_ANDROID_VR_SHELL_GLTF_ASSET_H_