Textures and Materials in Unity

Graphics Programming

Lecture 02 – Textures and Materials

Edirlei Soares de Lima

<edirlei.lima@universidadeeuropeia.pt>

Materials, Shaders and Textures

•

Materials: define how a surface should be rendered, including

references to textures, tiling information, color, etc.

–

The options available depend on which Shader the Material is using.

Shaders: small scripts that contain the mathematical

calculations and algorithms for calculating the color of each

pixel rendered, based on the lighting input and the Material

configuration.

•

Textures: are bitmap images.

–

A Material can contain references to textures, so that the Material’s

Shader can use the textures while calculating the surface color.

–

Textures can also represent other aspects of a Material’s surface such

as its reflectivity or roughness.

Unity Standard Shader

•

Standard Shader: built-in shader with a comprehensive set of

features.

–

Supports reflection, bump mapping, occlusion mapping, emission,

transparency, shadows, indirect light, etc.

Physically Based Shading: render objects in a way that accurately

simulates the flow of light of the real world.

Example of scene rendered using the standard shader on all models:

Standard Shader: Content and Context

•

The appearance of material based on the Standard Shader is

influenced by the content and context of the scene.

–

Context: light sources, skybox, indirect light, etc.

–

Content: scene objects, textures, etc.

•

Example of scene with variations in context:

Metallic vs. Specular Workflow

•

There are two options of workflow when creating a material

using the Standard shader: "Standard" and "Standard

(Specular setup)“.

–

Standard (Metallic setup): the shader exposes a “metallic” value that

states whether the material is metallic or not.

•

The Albedo color will control the color of the specular reflection and most light will

be reflected as specular reflections.

Standard (Specular setup): a specular color is used to control the color

and strength of specular reflections in the material.

•

This makes it possible to have a specular reflection of a different color than the

diffuse reflection for instance.

Metallic vs. Specular Workflow

Standard Shader

•

Parameters:

–

Rendering Mode

Albedo

Specular Mode: Specular

Metallic Mode: Metallic

Smoothness

Normal Map (Bump Mapping)

Height Map (Parallax Mapping)

Occlusion Map

Emission

Detail Mask & Maps

Textures: https://edirlei.com/aulas/cg/textures.zip

Standard Shader: Rendering Mode

•

Rendering Mode: defines whether the

object uses transparency, and if so,

which type of blending mode to use.

–

Opaque: suitable for normal solid objects with

no transparent areas.

–

Cutout: used to create a transparent effect that

has hard edges between the opaque and

transparent areas. Useful to create leaves or

cloth with holes.

–

Transparent: suitable for rendering realistic

transparent materials such as clear plastic or

glass. Reflections and lighting highlights will

remain visible.

Fade: allows the transparency values to

entirely fade an object out, including any

specular highlights or reflections it may have.

Standard Shader: Rendering Mode

•

Cutout Mode – Example

Standard Shader: Rendering Mode

•

Transparent Mode – Example

Standard Shader: Rendering Mode

•

Transparent Mode – Example with fully opaque areas

Standard Shader: Rendering Mode

•

Fade Mode – Example

Standard Shader: Albedo

•

Albedo: defines the base color or

texture of the material.

The alpha value of the Albedo color

controls the transparency level for the

material.

–

This only has an effect if the Rendering

Mode for the material is not set to

opaque.

Standard Shader: Albedo

•

Transparencies in areas of the material must be specified

in the texture alpha channel.

Standard Shader: Albedo

•

Transparencies in areas of the material must be specified

in the texture alpha channel.

Standard Shader: Specular

•

Specular (Specular Mode): represents

the direct reflections of light sources,

which typically show up as bright

highlights on the surface of objects.

Example:

Standard Shader: Specular

•

The color of the Specular parameter controls the strength and

color of the specular reflectivity.

The Smoothness parameter controls the clarity of the specular

effect.

–

Low smoothness value = even strong specular reflections appear

blurred and diffuse.

–

High smoothness value = specular reflections are crisper and clearer.

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Standard Shader: Metallic

•

Metallic (Metallic Mode): specular

reflections arise naturally depending

on the settings of the Metallic and

Smoothness levels (rather than being

explicitly defined as in the specular

mode).

Example:

Standard Shader: Metallic

•

The metallic parameter determines how “metal-like” the

surface is.

–

When a surface is more metallic, it reflects the environment more and

its albedo color becomes less visible.

–

When a surface is less metallic, its albedo color is more clear and any

surface reflections are visible on top of the surface color.

Standard Shader: Smoothness

•

Smoothness: defines how light scatters when

it hits the surface of the object. Represents

“

microsurface details” of the object.

Low Smoothness:

Standard Shader: Smoothness

•

Smoothness: defines how light scatters when

it hits the surface of the object. Represents

“

microsurface details” of the object.

Median Smoothness:

Standard Shader: Smoothness

•

Smoothness: defines how light scatters when

it hits the surface of the object. Represents

“

microsurface details” of the object.

High Smoothness:

Standard Shader: Normal Map

•

Normal Map (Bump Mapping): adds

surface detail such as bumps, grooves,

and scratches to a model which catch

the light as if they are represented by

real geometry.

Example of Normal Map texture:

Standard Shader: Normal Map

•

Example: screws in metal surface (without bump mapping)

Standard Shader: Normal Map

•

Example: screws in metal surface (with bump mapping)

Standard Shader: Normal Map

•

Bump mapping is a technique for simulating bumps on the

surface of an object. This is achieved by perturbing the

surface normals of the object and using the perturbed

normal during lighting calculations.

What are Surface Normals?

Standard Shader: Normal Map

•

What are Surface Normals?

Flat Surface:

Smooth Surface:

Standard Shader: Normal Map

•

What is Normal Mapping?

Standard Shader: Normal Map

•

What is Normal Mapping?

Standard Shader: Normal Map

•

How do I get or make normal maps?

–

During the 3D modelling process:

•

Very high resolution model + lower resolution “game ready” model.

From a texture:

•

ShaderMap - http://shadermap.com/

Can be produced by hand.

Standard Shader: Normal Map

•

Result:

Without Normal Mapping

Standard Shader: Normal Map

•

Result:

With Normal Mapping (directional light)

Standard Shader: Normal Map

•

Result:

With Normal Mapping (point light)

Standard Shader: Height Map

•

Height Map: as normal maps, height

maps add surface details. Are used to

give extra definition to surfaces and

render large bumps and protrusions.

Example of Height Map texture:

Standard Shader: Height Map

•

Height mapping (also known as parallax

mapping) is a similar concept to normal

mapping, however this technique is more

complex - and therefore also more

performance-expensive.

While normal mapping modifies the lighting

across the surface of the texture, parallax

height mapping goes a step further and

actually shifts the areas of the visible surface

texture around.

–

The effect is drawn onto the surface of the model

and does not modify the actual geometry.

Standard Shader: Height Map

Without Bump Mapping

With Normal Mapping

With Height Mapping

Standard Shader: Occlusion Map

•

Occlusion Map: used to provide

information about which areas of the

model should receive high or low

indirect lighting.

–

Example: concave areas usually do not

receive much indirect light.

Example of Occlusion Map texture:

Standard Shader: Occlusion Map

Without Occlusion Mapping

With Occlusion Mapping

Standard Shader: Emission

•

Emission: controls color and intensity of

light emitted from the surface. When

an emissive material is used in your

scene, it appears to be a visible source

of light itself.

Example:

Standard Shader: Emission

•

It is also possible to assign an emission map texture:

Standard Shader: Secondary Maps &

Detail Mask

Secondary Maps: allows the overlay of

a second set of textures on top of the

main textures (second Albedo color

map and a second Normal map).

•

The reason to use secondary maps is

to allow the material to have sharp

detail when viewed up close, while

also having a normal level of detail

when viewed from further away.

–

Without using a single extremely high

texture map to achieve both goals.

Standard Shader: Secondary Maps &

Detail Mask

•

Typical uses for detail textures are: adding skin detail,

adding tiny cracks and lichen growth to brick walls, adding

small scratches to metal containers.

Example (without secondary maps):

Standard Shader: Secondary Maps &

Detail Mask

•

Typical uses for detail textures are: adding skin detail,

adding tiny cracks and lichen growth to brick walls, adding

small scratches to metal containers.

Example (with secondary maps):

Other Built-in Shaders

•

FX: Lighting and glass effects.

GUI and UI: For user interface graphics.

Mobile: Simplified high-performance shader for mobile devices.

Nature: For trees and terrain.

Particles: Particle system effects.

Skybox: For rendering background environments behind all geometry.

Sprites: For use with the 2D sprite system.

Toon: Cartoon-style rendering.

Unlit: For rendering that entirely bypasses all light & shadowing.

Legacy: The large collection of older shaders which were superseded by the Standard Shader.

Exercise 1

1) Use textures and materials to improve the office scene.

•

Download: https://assetstore.unity.com/packages/3d/environments/snaps-

prototype-office-137490

•

Use scene:

•

ModernOffice_Interior_SampleLayout

•

The updated scene must:

•

Use textures for the main elements

(ground, walls, ceiling, tables,

computers, chairs, etc.)

•

Use normal mapping

Search for textures and normal maps

in the assets store (or Google).