Rendering/PBR

These principles only apply to Hedgehog Engine 2 games (Mario & Sonic at the Rio 2016 Olympic Games and onward)

PBR (Physically Based Rendering) refers to the current approach to 3D graphics material rendering used in most modern games. Its goal is to enhance the realism of surfaces by reflecting and refracting light more accurately than previous techniques. This is most noticeable in any kind of metallic surface:

Example of a metallic sphere in PBR rendering

PBR rendering tends to not make use of Diffuse maps and Specular Color Maps that were very common in non-PBR rendering. Instead, the primary texture maps it uses in their place are: Albedo Maps, Metallic Maps, Roughness Maps and Ambient Occlusion Maps.

Albedo Maps differ from Diffuse Maps by generally not containing any kind of depth or lighting information.

• 
  Diffuse texture example
• 
  Albedo texture example

Metallic Maps contain values ranging from 0-1(black-white). 0 determines a non-metallic surface while 1 determines a metallic surface. Values in between can and are used for stylistic and/or artistic purposes.

Metallic texture example

Roughness Maps change how the surface reflects light by making the reflection sharper using a value of 0 (smoother surface) or blurrier/more diffuse using a value of 1 (rough surface). This more or less equals the inverse of typical Gloss Maps used in non-PBR rendering.

Roughness texture example

Ambient Occlusion maps determine what areas of the surface should occlude more light when not directly illuminated. 0 represents the most light occlusion and 1 represents no light occlusion.

Ambient occlusion texture example

non-PBR vs PBR rendering (same lighting conditions):

• 
  Grass from Sonic The Hedgehog (2006) rendered in Blender
• 
  Grass from Shadow Generations rendered in Blender

In the Hedgehog Engine 2 games, PBR properties can be altered either by the Parameter map (_prm) when the material shader supports it (has the letter "p" in its name) or through a "PBRFactor" parameter in the surface's material if the shader being used doesn't support Parameter maps. The layout of these Parameter maps varies depending on the game and the shader.

All textures/maps used to create the final rendered image:

• 
  Albedo maps
• 
  Normal maps
• 
  Parameter maps
• 
  Emission maps

Final rendered image with added lighting: