Specular color map?

[Ben-Mack]

Hi everyone.

Now the Specular map only controls the intensity of the specular highlights, it's will be great if we have Specular color map (http://wiki.polycount.com/wiki/Specular_color_map), one more step toward to the realistic material.

Specular Color Map

A texture that controls the intensity/color of the specular highlights from real-time lights.

Usually a specular map simply controls the brightness of the highlights, at a per-pixel level. If the shader supports RGB the specular map can be used to colorize specular highlights, useful for surfaces that have more complex reflective properties like metals, beetle shells, etc.

[WestLangley]

We can add this to MeshPhongMaterial -- if there is interest. There hasn't been demand for it so far.

For the upcoming MeshPhysicalMaterial, I prefer to go with a metal-ness model, which is simpler for the average user, and does not require a specular map.

[simonihmig]

👍

[WestLangley]

@simonihmig What are you up-voting? What is your use case?

[simonihmig]

If I got it right, I can only influence the specular color via the specular property, but that affects the whole object. I have a single object (a person coming from a 3D scanner, not constructed by a human) with quite different "materials" (skin, clothes, shiny shoes, watch etc.), implemented as a single phong material with large texture maps. I would like to specify parts of that single material object as having a shiny surface (possible now with a specularMap) but also with different specular colors.

[WestLangley]

You got it right.

What is called specularMap in MeshPhongMaterial should have been named reflectivityMap. It is a grayscale map.

[Mugen87]

I'd like to revive this feature request since we have with 3MF a practical use case where a specular color map would be useful. I suggest the following:

• Rename specularMap to reflectivityMap for MeshBasicMaterial, MeshLambertMaterial and MeshPhongMaterial and use it to modulate reflectivity.
• Introduce specularMap (with new semantics) for MeshPhongMaterial only and (if set) use it instead of MeshPhongMaterial.specular.
• Besides, one would assume a specularMap is defined in sRGB color space whereas reflectivityMap is defined in linear color space.

[donmccurdy]

This is also one of the proposals of #16977. For that purpose, I think we'd want it on MeshPhysicalMaterial.

[mrdoob]

@Mugen87 that sounds good, but I think I would wait to see what GLTF decide first.

[Mugen87]

Oh, I was not aware that this topic is also discussed in the glTF space. But yeah, keep specularMap align with glTF sounds good 👍

[donmccurdy]

The glTF working group is nearly decided on KHR_materials_specular now, which would involve...

• specularColorTexture (RGB)
• specularTexture (A)

... along with scalar factors for each. Feedback (or PRs! 😇) would be welcome.

[donmccurdy]

Implemented in #22156.

[Mugen87]

AFAICS, This issue was also about refactoring specular map in other materials like MeshPhongMaterial (see #7290 (comment)). I would keep this issue open if there is still the intention to fix this.

[WestLangley]

Rather than enhancing MeshPhongMaterial, I would suggest we consider removing it -- unless there is evidence MeshStandardMaterial is measurably less performant for similar argument settings.

In any event, I would keep this post open in the mean time.

[Mugen87]

I would prefer not to discuss the removal of materials in this issue. Open issues are:

• Rename specularMap to reflectivityMap for MeshBasicMaterial, MeshLambertMaterial and MeshPhongMaterial and use it to modulate reflectivity.
• Introduce specularMap (with new semantics) for MeshPhongMaterial only and (if set) use it instead of MeshPhongMaterial.specular.

[WestLangley]

@WestLangley said:

From #9339 (comment)

Regarding an RGB.specularMap, I now see little benefit to adding this. Such a feature may be useful in modeling metals, but MeshPhongMaterial does not do a good job of representing metals, anyway. MeshStandardMaterial, on the other hand, does. Consequently, I have abandoned adding an RGB .specularMap to MeshPhongMaterial.

My recommendation at this point is to leave MeshPhongMaterial as-is. Sophisticated users can use MeshStandardMaterial.

From #9339 (comment)

Note, we use the property .specularMap elsewhere. An RGB .specularMap is used in the glTF Specular-Glossiness extension, where it modulates .specular, the specular reflectance of the material.

From #9339 (comment)

I still would be in favor of renaming the current grayscale .specularMap to .reflectivityMap, as it modulates the .reflectivity property in the MeshBasic/Lambert/Phong materials.

//

But I would not waste time on any of this without discussing the removal of MeshPhongMaterial first. MeshStandardMaterial is far superior -- except maybe in performance.

[donmccurdy]

I think it's true that when users choose MeshPhongMaterial or MeshLambertMaterial, it's often for the improved performance — not because they prefer these older shading models. If we could offer a shading model that approximates Standard (and has a similar parameterization) with cost similar to Phong or Lambert, that would be valuable, and would make it much easier to adapt content to different devices.

Related:

• Faster PBR Material #21578

Whether the parameterization of MeshPhongMaterial should be changed if it is kept, I don't know. I am wondering why MeshBasicMaterial has a specular property at all. 🤔

[WestLangley]

@donmccurdy Are you aware of any studies quantifying the performance of Phong vs. Standard?

[donmccurdy]

Lots of anecdotes but no studies, sorry! 😐

[WestLangley]

Hmm... We don't want to begin with a false premise. Note that the shaders share significant code.

[donmccurdy]

Another related issue:

• Material.fromMaterial #22179

[NoriyukiIchijo]

Regarding this, the condition in writeMaterial of GLTFMaterialsSpecularExtension may be wrong.
if (!material.isMeshPhysicalMaterial || (material.specularIntensity === 1.0 && material.specularColor.equals(DEFAULT_SPECULAR_COLOR) && !material.specularIntensityMap && !material.specularColorTexture)) return;
Does the last one mean !material.specularColorMap since I couldn't find such property in MeshPhysicalMaterial?
And I'll be glad if we have more uvs in nameConversion like
uv2: 'TEXCOORD_2', uv3: 'TEXCOORD_3', ...

[WestLangley]

Does the last one mean ! material.specularColorMap

/ping @elalish

[elalish]

Probably? Did I write that?

[WestLangley]

@elalish It appears you did. #25335