ExchangeMapper Material Definition Mapper Manual

Table of Contents

• Introduction
• MaterialMappingInterface
• Further Reading

Introduction

It is possible to translate a material definition by defining a maxon::material::MaterialMappingInterface.
While having a perfect match from a material definition to another is unrealistic, some material definitions do not support displacement, the maxon::material::MaterialMappingInterface ensures this operation to be done in the best possible way, by for example inverting a roughness value.

MaterialMappingInterface

A mapping from a material definition to another is done in two steps:

1. the constant parameters (e.g. maxon::material::PackedConstantParameter, maxon::material::TypedConstantParameter) are taken in considering.
2. the non-constant ones (maxon::material::TextureBuffer, maxon::material::ImageReference, maxon::material::SubstanceReference) follow.

There are two methods to override:

• maxon::material::MaterialMappingInterface::PassOne(): Overwrite to store constant parameters in a maxon::material::MaterialExchangeData target instance from the provided maxon::DataDictionary.
  This maxon::DataDictionary corresponds to the maxon::material::MaterialExchangeData::_parameters of the maxon::material::MaterialExchangeData source instance.
  It also returns the ID(s) of the texture(s) that needs to be exported (e.g. if the color channel is disabled then it's not needed to export the texture attached to that color channel).
  
  
• maxon::material::MaterialMappingInterface::PassTwo(): Overwrite to store non-constant parameters into a maxon::material::MaterialExchangeData target instance from the provided maxon::HashMap<maxon::Id, maxon::Data>.
  This HashMap corresponds to the maxon::material::MaterialExchangeData::_textures of the maxon::material::MaterialExchangeData source instance.
  Finally, it returns the maxon::material::MaterialExchangeData containing the information retrieved in the two steps.

Each material mapping should be registered in the maxon::material::MaterialMappers registry as a maxon::material::MaterialMappingDescription that contains information about the maxon::Id of the source material definition and the target material definition and the maxon::material::MaterialMappingRef to performs this mapping.

Further Reading

• ExchangeMapper Overview Manual
• ExchangeMapper Material Definition Manual
• ExchangeMapper Material Export Manual
• ExchangeMapper Material Import Manual