View source for 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:

{| class="wikitable" style="margin:auto"
|+
!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 [[wikipedia:DirectDraw_Surface|DDS]] files.

HE2 is programmed with [[wikipedia:Direct3D#Direct3D_11|Direct3D 11]] (or newer), which means all DDS encodings are available for use.

More info on DDS block compression can be found [https://learn.microsoft.com/en-us/windows/win32/direct3d11/texture-block-compression-in-direct3d-11 here].

{{Notice|type=info|content=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
| suffix = _abd
| composition = RGBA
| encoding = * <code>BC1_UNORM</code> when opaque,
* <code>BC7_UNORM</code> when transparent
}}

[[File:HE2 Textures dif.png|thumb|<code>chr_big_fur_abd.dds</code> from Shadow Generations]]
Albedo textures are color-transparency textures that are sampled directly for the base color of a material.

See [[Hedgehog Engine 2 - Physically Based Rendering (PBR)#Albedo|albedo]] for reference.

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=== Transparency ===

{{Texture Overview
| suffix = _alp
| composition = Grayscale
| encoding = <code>BC4_UNORM</code>
}}

[[File:HE2 Textures transparecy.png|<code>cmnisl_blackstone501_tk1_alp.dds</code> from Shadow Generations|alt=cmnisl_blackstone501_tk1_alp.dds from Shadow Generations|thumb]]

Transparency textures determine the transparency of a material.

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

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=== Falloff ===

{{Texture Overview
| suffix = _fal
| composition = Color
| encoding = <code>BC1_UNORM</code>
}}
[[File:HE2 Textures fal.png|thumb|<code>chr_big_fur_fal.dds</code> from Shadow Generations]]
[[File:Falloff animation.gif|thumb|A camera rotating around Suzanne with a raw falloff factor. The albedo texture is black, and the falloff texture is white]]
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.

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=== Emission ===

{{Texture Overview
| suffix = _ems
| composition = HDR
| encoding = <code>BC6H_UF16</code>
}}
[[File:HE2 Texture ems.png|thumb|<code>bos_mephiles_body_ems.dds</code> from Shadow Generations]]
Emission textures make parts of a model emit light. These are usually [https://en.wikipedia.org/wiki/High_dynamic_range HDR] textures.

See [[Hedgehog Engine 2 - Physically Based Rendering (PBR)#Emission|emission]] for reference.

<div style="clear: both"/>

=== PRM ===

{{Texture Overview
| suffix = _prm
| composition = RGBA
| encoding = * <code>BC1_UNORM</code> when no alpha channel is needed,
* <code>BC3_UNORM</code> when alpha channel is needed
}}
[[File:HE2 Textures prm.png|thumb|<code>chr_big_rod_prm.dds</code> from Shadow Generations]]
PRM textures, an abbreviation for “Parameter”, are the defacto PBR textures of Hedgehog Engine 2 games.

If you are unfamiliar with Physically based rendering, you should look into the [[Hedgehog Engine 2 - Physically Based Rendering (PBR)|Physically Based Rendering]] documentation before trying to edit materials.

<div style="clear: both"/>

Each channel contains one PBR map:

{| class="wikitable"
|+
!Channel
!Contents
!"Default" value
!Notes
!Example from <code>chr_big_rod_prm.dds</code>
|-
|Red
|[[Hedgehog Engine 2 - Physically Based Rendering (PBR)#Specular|Specular]]
|0.5
|The engine multiplies the sampled value by 0.5
|[[File:HE2 Textures prm r.png|thumb]]
|-
|Green
|[[Hedgehog Engine 2 - Physically Based Rendering (PBR)#Smoothness|Smoothness]]
|0.8
|Blender uses a roughness setup, which is just the inverse of smoothness
|[[File:HE2 Textures prm g.png|thumb]]
|-
|Blue
|[[Hedgehog Engine 2 - Physically Based Rendering (PBR)#Metallic|Metallic]]
|0
|
|[[File:HE2 Textures prm b.png|thumb]]
|-
|Alpha
|[[Hedgehog Engine 2 - Physically Based Rendering (PBR)#Ambient Occlusion|Ambient Occlusion]]
|1
|Many tutorials claim that AO is just multiplied into the albedo channel, which is <b>not</b> true.

AO gets mixed into the lighting, which is difficult to replicate in render engines like Cycles, but doable in Eevee.
|[[File:HE2 Textures prm a.png|thumb]]
|}

{{notice
| type = note
| content = Older HE2 games, primarily Sonic Forces and Mario & Sonic at the Rio 2016 Olympic Games use a slightly different PRM setup:

{{{!}} class="wikitable"
{{!}}+
!Channel
!Contents
!Notes
{{!}}-
{{!}}Red
{{!}}Specular
{{!}}If the value is above 0.9, the material gets treated as completely metallic.
{{!}}-
{{!}}Green
{{!}}Smoothness
{{!}}Same as above
{{!}}-
{{!}}Blue
{{!}}Ambient Occlusion
{{!}}
{{!}}-
{{!}}Alpha
{{!}}Metallic
{{!}}Only used in select shaders like <code>MCommon</code>, where the specular-above-0.9 check isn't done
{{!}}}
}}

=== Normal map ===

{{Texture Overview
| suffix = _nrm
| composition = RG
| encoding = <code>BC5_UNORM</code>
}}
[[File:HE2 Textures nrm.png|thumb|<code>chr_big_rod_nrm.dds</code> from Sonic X Shadow Generations]]
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.

<div style="clear: both"/>

{{notice
| type = note
| content = 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
| suffix = _flw
| composition = RG
| encoding = <code>BC5_UNORM</code>
}}
[[File:HE2 Textures flw.png|thumb|<code>chr_shadow_fur_flw.dds</code> from Shadow Generations]]
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.

<div style="clear: both"/>

{{notice
| type = note
| content = Older flow texture have a blue channel, which went unused.
}}

==== Fur Noise ====

{{Texture Overview
| suffix = _fur
| composition = RGBA
| encoding = <code>BC3_UNORM</code>
}}
[[File:HE2 Textures fur.png|thumb|<code>chr_shadow_fur_fur.dds</code> from Shadow Generations]]
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.

<div style="clear: both"/>

==== Iridescence reflection ====

{{Texture Overview
| suffix = _ref
| composition = Color
| encoding = <code>BC1_UNORM</code>
}}

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

{| class="wikitable" width="128px" style="margin-left: auto; margin-right: 0px;"
|-
| [[File:HE2 Textures ref.png|center]]
<code>w05_ruins_biometal_ref.dds</code> from Sonic X Shadow Generations
|}

<div style="clear: both"/>

==== Offset map ====

{{Texture Overview
| suffix = _off
| composition = RG
| encoding = <code>BC5_UNORM</code>
}}
[[File:HE2 Textures off.png|thumb|<code>w09_btl02_poisonswamp_s3_jh1_off.dds</code> from Shadow Generations]]
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.

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