Hedgehog Engine 2 - Textures

Hedgehog Engine 2 games limit themselves to a few texture types, which can make configuring materials difficult, as many shaders use certain types differently than what their name suggests.

Here is a list of all texture types and how they are most commonly used:


Type	Primarily used with	Occasionally used with
diffuse	Albedo, Falloff	/
transparency	Transparency	albedo, mask
emission	Emission	/
reflection	Flow map, Fur noise	Iridescence reflection, Offset map
specular	PRM	/
normal	Normal map	/

File formats and encodings

Textures are always stored in DDS files.

HE2 is programmed with Direct3D 11 (or newer), which means all DDS encodings are available for use.

More info on DDS block compression can be found here.

Info

HE2 games often use BC7 encoding for its higher image quality. If the recommended encoding does not give satisfying results, you can always use BC7 encoding to increase the quality, but keep in mind that this will also increase file size!

File streaming

Many textures in Frontiers and onwards make use of file streaming to reduce texture-load-time and reuse the same texture between multiple archives.

You can pack/unpack/view info of streamed texture packages using NeedleTextureStreamingUtility.

Kinds of textures

The majority of textures used by materials are one of the following kind of textures.

Albedo


Texture overview
File Suffix	_abd
Composition	`RGBA`
Recommended encoding	`BC1_UNORM` when opaque, `BC7_UNORM` when transparent

Albedo textures are color-transparency textures that are sampled directly for the base color of a material.

See albedo for reference.

Transparency


Texture overview
File Suffix	_alp
Composition	`Grayscale`
Recommended encoding	`BC4_UNORM`

Transparency textures determine the transparency of a material.

Usually transparency is relayed to Albedo textures, and actual opacity textures are only used when special alpha compositing happens.

Falloff


Texture overview
File Suffix	_fal
Composition	`Color`
Recommended encoding	`BC1_UNORM`

Falloff textures change the color of the albedo texture based on the viewing angle: The greater the angle between the camera and the surface of the model, the greater the influence.

Depending on the shader, the falloff color either gets mixed with the albedo color or added to it.

Additionally, shaders with falloff colors or textures basically always come with a parameter that controls how the falloff factor gets calculated.

Emission


Texture overview
File Suffix	_ems
Composition	`HDR`
Recommended encoding	`BC6H_UF16`

Emission textures make parts of a model emit light. These are usually HDR textures.

See emission for reference.

PRM


Texture overview
File Suffix	_prm
Composition	`RGBA`
Recommended encoding	`BC1_UNORM` when no alpha channel is needed, `BC3_UNORM` when alpha channel is needed

PRM textures, an abbreviation for “Parameter”, are the defacto PBR textures of Hedgehg Engine 2 games.

If you are unfamiliar with Physically based rendering, you should look into the Physically Based Rendering documentation before trying to edit materials.

Each channel contains one PBR map:


Channel	Contents	"Default" value	Notes
Red	Specular	0.5	The engine multiplies the sampled value by 0.5
Green	Smoothness	0.8	Blender uses a roughness setup, which is just the inverse of smoothness
Blue	Metallic	0
Alpha	Ambient Occlusion	1	Many tutorials claim that AO is just multiplied into the albedo channel, which is not true. AO gets mixed into the lighting, which is difficult to replicate in render engines like Cycles, but doable in Eevee.

Normal map


Texture overview
File Suffix	_nrm
Composition	`RG`
Recommended encoding	`BC5_UNORM`

Normal map textures are used for faking bumps and dents on a model to affect lighting, falloff, environment maps and similar.

See normal mapping for reference.

Note

HE2 always automatically calculates the blue / Z channel for normal maps. That means, when using a three-component texture for a normal map, the blue channel gets ignored.

Other

Flow Map


Texture overview
File Suffix	_flw
Composition	`RG`
Recommended encoding	`BC5_UNORM`

Flow textures are two-component textures that, similar to normal maps, encode a direction. Each pixel determines the direction of “flow” to use when sampling the noise texture.

Note

Older flow texture have a blue channel, which went unused.

Fur Noise


Texture overview
File Suffix	_fur
Composition	`RGBA`
Recommended encoding	`BC3_UNORM`

Fur noise textures get sampled based on the direction of a flow map to create a “flowing lines” type of pattern.

The color channel gets multiplied into the albedo color, while the alpha channel determine the specularity.

This allows for characters to have fine details without needing huge textures.

Iridescence reflection


Texture overview
File Suffix	_ref
Composition	`Color`
Recommended encoding	`BC1_UNORM`

Iridescence shaders use these reflection textures to create their effect of the same name.

Offset map


Texture overview
File Suffix	_off
Composition	`RG`
Recommended encoding	`BC5_UNORM`

Offset maps are basically normal maps that are used to distore another texture by shifting the sample coordinate.

These are often used with things like water or wind.