NTC Manifest File Format

Manifest files are using the JSON format with the following schema.

Document

The root of the manifest document is an object with the following fields.

Field Name	Type	Default	Description
textures	array of ManifestEntry	(required)	List of textures to include in the texture set
width	int	derived	Custom width for the texture set
height	int	derived	Custom height for the texture set

ManifestEntry object

Field Name	Type	Default	Description
fileName	string	(required)	Path to the texture image file relative to the manifest file location.
bcFormat	string	none	Block compression format (BC1 - BC7) that should be used for transcoding of this texture after NTC decompression. This is only a hint, and implementations may use a different format.
channelSwizzle	string	derived	Set and order of channels from this image that will be used in the NTC texture set. Must be 1-4 characters long and only contain R, G, B, A characters, such as "BGR". If not specified, all channels from the image are used in their original order.
firstChannel	int	derived	First channel in the NTC texture set that will be occupied by this texture, 0-15. If not specified, the first available channel is selected. The texture's channels (after swizzle) must fit into the texture set, i.e. no channel may have an index higher than 15.
isSRGB	bool	false	If set to true, the texture data will be interpreted as sRGB encoded.
lossFunctionScale	float or array	1.0	Loss function scales for the texture's channels as an array, or a single number to apply to all channels.
mipLevel	int	0	Mip level in the NTC texture set that the specified image will be loaded into.
name	string	derived	Name of the texture in the NTC texture set. If not provided, the file name without extension is used instead.
semantics	object	empty	Map of semantic labels (strings) to channel ranges (also strings). For each semantic label (see below for a full list), a set of channels is specified using a substring of "RGBA". This means that channel order must be preserved; "RG" and "GBA" are valid channel ranges, while "BGA" is not.
verticalFlip	bool	false	If set to true, the texture will be flipped along the Y axis on load.

Semantic labels

The semantic labels are case-insensitive, and some of them support multiple versions. The following labels are recognized:

• Albedo
• Alpha, Mask, AlphaMask
• Displ, Displacement
• Emissive, Emission
• Glossiness
• Metalness, Metallic
• Normal
• Occlusion, AO
• Roughness
• SpecularColor
• Transmission

Note that the semantic labels are currently not stored in the NTC files. Some of them are used by the Explorer app to correctly map the textures to PBR inputs of the material in the 3D view.

The AlphaMask (and synonyms) label can be used to enable special processing for the alpha channel. For more information, see the Settings and Quality Guide.

Example manifest

{
    "textures": [
        {
            "fileName": "PavingStones070_4K.diffuse.tga",
            "name": "Diffuse",
            "bcFormat": "BC7",
            "isSRGB": true,
            "semantics": {
                "Albedo": "RGB"
            }
        },
        {
            "fileName": "PavingStones070_4K.normal.tga",
            "name": "Normal",
            "bcFormat": "BC7",
            "semantics": {
                "Normal": "RGB"
            }
        },
        {
            "fileName": "PavingStones070_4K.roughness.tga",
            "name": "Roughness",
            "bcFormat": "BC4",
            "semantics": {
                "Roughness": "R"
            }
        }
    ]
}