Implement glTF 2 model support

[IAmNotHanni]

Introduction

glTF is the new, open source standard for 3D data. It is a node-based format which can either be raw .gltf or compressed .glb. Blender supports import and export of glTF models natively.

Overview

What has been done previously

• Loading of glTF models (very buggy because of old code base).
• No textures or animations were loaded from the glTF file.
• See v0.1-alpha.1

Roadmap

• [X] Include tinygltf as dependency for loading glTF models from files.
• [x] Create a RAII wrapper class for glTF models.
• [x] Load the glTF model file using tinygltf.
• [x] Create a structure for glTF model primitives.
• [ ] Create a structure for glTF model nodes. This requires some node hierarchy based on smart pointers.
• [x] Create a structure for glTF model materials.
• [x] Extract textures which are directly stored in the glTF file (will be required later).
• [ ] Implement a method for drawing models in command buffer recording.
• [ ] Implement a wrapper for push constants.

Not in the scope of this issue

• Loading animations.
• Physically based rendering (PBR) settings.
• Vertex weight.
• Additional glTF data/features.

Ideas for the future

• Hot reload: reload the glTF file if it has been changed. We would need some cross-platform mechanism to detect changes in a file. Maybe SHA-1 would be the easiest way to go? But it might be too slow.

Resources

https://github.com/KhronosGroup/glTF https://www.khronos.org/gltf/ https://stackoverflow.com/questions/tagged/gltf https://github.com/SaschaWillems/Vulkan-glTF-PBR https://docs.blender.org/manual/en/2.80/addons/io_scene_gltf2.html

[IAmNotHanni]

When implementing the node structure, I would like to take the octree code as inspiration. It would be cool if they followed the same design decisions in terms of smart pointer usage. Herb Sutter gave a nice talk about this: