Hardsurface Art Production Shader Setup

After UV mapping and baking are complete, the asset moves into the texturing stage. This is where the production process shifts from being mostly technical to becoming strongly artistic.

The low-poly, UVs, and bake are stages where the artist works with numbers, budgets, topology rules, projection quality, and technical constraints. Texturing is closer to concept art and high-poly sculpting in terms of creative responsibility. It defines how the object reads as a material, how it reacts to light, how new or worn it feels, and how believable it becomes in the player’s hands.

To work effectively at this stage, the artist needs a confident understanding of PBR and a clear command of the two major industry workflows:

• Specular / Glossiness
• Metallic / Roughness

Both are widely used. Both can produce physically plausible results. Each has its own strengths, limitations, and production use cases. The choice between them is rarely just a matter of personal preference. It is usually defined by the engine, platform, asset type, shader setup, and production constraints.

The Specular / Glossiness workflow usually uses the following core texture set:

• Diffuse
• Specular
• Gloss
• Normal

Diffuse

The Diffuse map is stored in sRGB and defines the base color of the surface. More precisely, it represents the light energy that is diffusely reflected by the material, while the rest of the light is absorbed.

For dielectric materials, this map carries the visible surface color.

For metals, the diffuse map is black because metals do not have diffuse reflection in the same way dielectrics do. In PBR, the color of a metal is carried through its specular response rather than diffuse color.

Specular / F0

The Specular map, also stored in sRGB, controls both the color and intensity of reflection.

For dielectrics, it is usually a dark, neutral gray value. For metals, it becomes fully colored:

• yellow for gold
• warm reddish-brown for copper
• light gray for steel
• pale yellow-gray for brass
• tinted values for coated or treated metals

This gives the artist direct control over how the material reflects light.

Gloss

The Gloss map is a linear grayscale texture. It defines surface smoothness.

• White means a smoother, glossier surface.
• Black means a rougher, more diffuse surface.

Gloss is essentially the inverse of roughness.

The main advantage of the Specular / Glossiness workflow is direct control over reflectivity.

The artist explicitly defines how the surface reflects light, both in color and intensity. This gives more flexibility for unusual materials and often produces richer, more intuitive results for metals.

This is one of the key reasons we author weapon textures in Specular / Glossiness. Weapons contain a large amount of visible metal: steel, brass, copper, anodized aluminum, parkerized parts, blued surfaces, coated receivers, worn edges, and exposed contact areas. For these surfaces, Specular / Glossiness provides a very direct and artist-friendly way to tune material response.

It is also easier to handle transitions between metal and non-metal materials. Dirt, paint, dust, oil, and worn coatings can be layered without forcing the underlying metal to lose its metallic behavior.

However, this workflow requires a stronger understanding of physical material properties. Because the artist has more control, there are also more ways to make mistakes. It is very easy to create materials that look visually interesting but behave incorrectly under lighting.

Downsides of Specular / Glossiness

The main disadvantage is texture memory.

Specular is an RGB texture, and because of compression requirements it often needs to be stored in a higher-quality format such as BC7. This can make it significantly heavier than a simple grayscale metallic channel stored in a more compact format.

Specular / Glossiness also makes it easier to break energy conservation if the artist does not understand how diffuse and specular values should relate to each other. In other words, the workflow gives more control, but also more responsibility.

For experienced artists, that control is valuable. For beginners, it can become a source of physically incorrect materials.

The Metallic / Roughness workflow uses a different core texture set:

• Base Color
• Metallic
• Roughness
• Normal

Base Color

The Base Color map is stored in sRGB and combines two roles in one texture.

For dielectrics, it represents diffuse surface color. For metals, it represents reflection color.

In a simplified sense, Base Color contains both the diffuse role and the colored specular role, while the shader decides how to interpret it based on the metallic mask.

Metallic

The Metallic map is a linear grayscale texture.

• Black means dielectric.
• White means metal.

Intermediate values are usually used for transitions, such as dust over metal, corrosion, dirt buildup, or partially covered surfaces. In clean material definition, most surfaces should be either black or white, because a material is usually either metallic or non-metallic.

Roughness

The Roughness map is also a linear grayscale texture.

• White means rough.
• Black means smooth.

It is the inverse of Gloss.

The main production advantage of Metallic / Roughness is channel packing.

Because Metallic, Roughness, and Ambient Occlusion are all grayscale maps, they can be stored together in a single packed texture. A common setup is:

R = Metallic
G = Roughness
B = Ambient Occlusion
A = Opacity or another mask

This means one texture file can contain up to four different maps, while Base Color remains a separate RGB texture.

Fewer texture files usually means fewer texture fetches, lower memory use, and a more efficient material setup.

The second major advantage is reduced room for error. The artist does not manually define dielectric reflectivity. The shader uses a standard value, which makes the workflow more predictable and harder to break.

In Specular / Glossiness, the artist controls that value directly. This allows more flexibility, but it also creates more opportunities to violate physical correctness.

Downsides of Metallic / Roughness

The main weakness of Metallic / Roughness appears at transitions between metal and non-metal materials.

Paint over steel, dust on aluminum, corrosion, dirt in cavities, worn coatings, and exposed metal edges are all cases where different material types meet on the same surface.

In Metallic / Roughness, these transitions are usually represented through intermediate metallic values. This can create a gray film effect at the boundary. Instead of reading as chipped paint over steel, the result can start to feel like plastic with metal painted onto it.

In Specular / Glossiness, this problem is easier to avoid because Diffuse and Specular are controlled separately. The underlying metal can remain physically metallic while dirt, paint, or dust exist above it as separate material layers.