ExchangeMapper Material Definition Manual

Table of Contents

• Introduction
• Overview
• Constant Value
• Texture Value
• Further Reading

Introduction

A Material Definition (FBX, GLTF, USDSurface) is represented by a series of maxon::MAXON_ATTRIBUTE and a namespace containing only maxon::MAXON_ATTRIBUTE is called a material description bundle.

Default values must be defined via the Resource Editor.

A maxon::material::MaterialExchangeData representing this series of attributes can be created to define a material definition as a single data structure.

There are two categories of data that can be stored in a maxon::material::MaterialExchangeData:

• Constants values: POD values like int, float, vector
• Texture values: which are more complex like a gradient, a bitmap reference.

To help build a maxon::material::MaterialExchangeData, the maxon::material::ParameterStorageInterface provides static helpers to build a complete maxon::material::MaterialExchangeData.

This maxon::material::ParameterStorageInterface can also be used to retrieve a complete material definition from an incomplete maxon::material::MaterialExchangeData by retrieving default values if needed.

Overview

A maxon::material::MaterialExchangeData is the data representation of a material definition.

A maxon::material::MaterialExchangeData may not be the complete representation of a material definition.

As an example, a maxon::material::MaterialExchangeData may have stored only information about the diffuse color, while the overall material definition supports diffuse color and reflection.

A maxon::material::MaterialExchangeData is made of:

• maxon::material::MaterialExchangeData::_materialTypeId : a maxon::Id of the material definition the current maxon::material::MaterialExchangeDataRef is representing.
• maxon::material::MaterialExchangeData::_parameters : a maxon::DataDictionary storing all constants values (POD), as maxon::material::PackedConstantParameter or maxon::material::TypedConstantParameter. During the export/mapping phase, it's processed first.
• maxon::material::MaterialExchangeData::_textures: a maxon::HashMap<maxon::Id, maxon::Data> storing all textures values, as maxon::material::TextureBuffer, maxon::material::ImageReference or maxon::material::SubstanceReference. During the export/mapping phase, it is processed as second step: this way it is possible to avoid baking unnecessary texture by reading previously loaded parameter (e.g. for the standard Cinema 4D material, it's not necessary to export the diffuse texture if the diffuse channel is disabled).

Constant Value

A constant value can be represented by:

• maxon::material::PackedConstantParameter: a type-agnostic, but still a maxon::MAXON_DATATYPE, parameter.
• maxon::material::TypedConstantParameter: a type-known material parameter.

Both have a boolean _isConstant and UInt _dynamicTimestamp members.

The _isConstant defines whether the parameter is constant and only requires a single value for the representation.

The _dynamicTimestamp is the time stamp of the dynamic texture-driven parameter. This is used to manage the parameter dirty state, especially useful for consistent viewport representation.

Texture Value

A Texture value can be represented by:

• maxon::material::TextureBuffer: a maxon::BaseArray of maxon::Vector4d32 representing all pixels of the texture buffer. This is useful to store a gradient.
• maxon::material::ImageReference: an absolute path to an image reference.
• maxon::material::SubstanceReference: an absolute path to a substance "*.sbar" file with the asset and the channel to be used.

Further Reading

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