2022 Talk About X3D PBR glTF - michaliskambi/x3d-tests GitHub Wiki

Title: Physically based rendering (PBR) in X3D 4, using glTF with X3D 4

Watch the recorded webinar here: https://www.youtube.com/watch?v=iQ0s1V37tAw

March 29 (Tuesday)

Time: ~45 mins talk + 15 min for QA

Register on https://www.web3d.org/pbr-x3d4-using-gltf

Summary

We will go over the new features in X3D 4 related to materials, lighting and textures. These include

• physically based rendering,
• normal maps,
• more ways to affect materials by textures,
• close alignment with PBR in glTF,
• upcoming work: environment light.

I will make this a practical session: for everything that I'll describe, I'll also show how to actually write it in X3D, and render using Castle Game Engine / view3dscene.

Short Plan

• Overview of X3D
• Materials in X3D 4: unlit, PBR, Phong
• Lights in X3D 4: unbounded intensity, upcoming environment light
• Textures in X3D 4: modify any material parameter
• Practical examples of how to write all above in X3D, classic and XML
• Inline glTF in X3D
• Strategy to express glTF concepts, in particular PBR, using X3D
• Example: export Blender -> glTF, inline in X3D

Full Plan

• Overview of important X3D concepts

  • Shape
  • a number of possible geometry nodes
  • Appearance
  • with materials and textures

• Materials in X3D 4

  3 possible material nodes in X3D 4:

  • UnlitMaterial
  • PhysicalMaterial
  • Material

  For all materials:

  • all their parameters can be affected by textures, e.g. diffuseColor and diffuseTexture
  • all material types have a normal texture
  • all material types have emissive
  • all material types have transparency

  UnlitMaterial:

  • Nothing more.
  • Just emissive (color and texture).
  • Calculation ignores lighting, and is expected to be optimized.

  Material:

  • Phong lighting model.
  • Backward-compatible with X3D 3.
  • Parameters: ambient, diffuse, specular, shininess, occlusion

  PhysicalMaterial:

  • PBR lighting model, compatible with glTF 2.0 PBR metallic-roughness model.
  • Parameters: base, metallic, roughness, occlusion
  • Note: common metallicRoughnessTexture to parametrize both metallic-roughness, like glTF.

• Lights:

  Same lights as you know from X3D 3:

  • PointLight
  • SpotLight
  • DirectionalLight

  But now with unbounded intensity.

  Work in progress:

  • EnvironmentLight (expected to be largely compatible with Khronos KHR_lights_environment, EXT_lights_image_based) https://github.com/michaliskambi/x3d-tests/wiki/Image-Based-Lighting-(EnvironmentLight-node)

• Textures:

  You can specify them at material slots.

  Textures in Appearance.texture also still allowed, backward-compatible: act as Material.diffuseTexture/PhysicalMaterial.baseTexture/UnlitMaterial.emissiveTexture.

  Treatment of grayscale and RGB simpler. Grayscale is just equivalent to red=green=blue.

• Writing above in X3D, classic and XML

• Inline glTF

• Strategy to express glTF concepts, in particular PBR, using X3D

• Example: export Blender -> glTF, inline in X3D

• Links about development:

  Follow from https://github.com/michaliskambi/x3d-tests/wiki/X3D-version-4:-New-features-of-materials,-lights-and-textures https://github.com/michaliskambi/x3d-tests/wiki/Converting-glTF-to-X3D

  My viewer: Castle Game Engine and view3dscene https://castle-engine.io/ https://castle-engine.io/view3dscene.php

  Conversion: use view3dscene, or online https://castle-engine.io/convert.php