shaders_textures.pdf

Shaders and Textures in Artlantis 2.0

By Gérard Bomer, Abvent

In Artlantis, “Shaders” and / or “Textures” are used to define the aspect of materials.

In Artlantis there are a few procedural shaders that have a color for the diffuse (Basic, Expert, Fresnel

Water, etc.) The majority of shaders have images to define the diffuse (Bricks, Wood...).

1/ Procedural Shaders

Procedural shaders (Basic or Expert) are recommended:

- for simple surfaces because they use very little memory,

- as a support for texture mapping

Basic and Expert shaders can simulate several surfaces.

“Basic” Shader sample: from matte to lacquer painting by changing the reflection and shininess:

R=0 - S= 0

R=0.2 - S=20

R= 0.5 - S= 350 R=0.5 - S=1000

Diffuse=green Diffuse=green

Diffuse=green

“Expert” shader sample:

Aluminum, Steel, Chrome, Bubble

Shininess=160 Shininess=400

Shininess=1000 Shininess=900

Diffuse=Dark-gray Diffuse=Black

Diffuse=Black

Reflection=Gray Reflection=Gray-blue

Reflection=white Reflection=light gray

Transparency=light gray

Other procedural shaders (Fresnel Water, Fresnel Glazing, etc.) are used for specific cases, which cannot

be simulated by others.

“Fresnel Water” shader sample:

2/ Image Shaders

Image Shaders are "pre-set" materials, ready to use. They have common behaviors:

- Automatic repeat of the diffuse image file to cover the entire surface with a perfect tiling

- Sliders with minimum and maximum values are pre-set to prevent faulty settings, i.e. coating

shaders have no reflection

- Unique and Simple user interface (Some image channels and parameters are hidden)

The Mix Color:

The diffuse is defined by an image that has its own colors, but it is possible to modify this color with the

“mix color” function.

This is an RGB color, and the neutral color is gray. Gray does not change the original picture aspect,

even if the “Mix” box is checked.

Sample: changing the mix color on the wall in the back

Mix Color in the UI

No mix

Mix=Brown

Mix=Green

Tip: If your scene illumination is correct except for one material that is lighter or darker than you

expect, you can use the Mix Color.

Note: it has a greater effect on direct lighting.

- Automatic scaling with the model

In this sample, dark gray was mixed with the carpet shader

Reflection and Shininess

These work exactly the same way as procedural shaders (see above) but minimum and maximum values

can be limited. To change these limits, use “Create Shader” feature.

Note: if Shininess is 0, Reflection does not have any effect on your scene. You have to set a minimum

value to Shininess to see Reflection.

Tips: if Reflection > 0 the LED is red; if you click on it, Reflection is reset to 0

Here, the maximum value of Reflection is limited to 0.4 (max. possible is 1.0)

Bump mapping and/or Normal mapping

These parameters can simulate roughness or relief of the surface. But there is no modification of the

geometry.

Relief simulation with Bump mapping:

Tip: if Bump number is 0, the LED becomes red; by clicking on it, the Bump is reset to 0 (neutral

position)

(Bump map and Normal map samples are detailed in the “Create Shader” tutorial.)

Note: If the Normal map slider is disabled it means that there is no Normal map in the shader definition.

Transparency

All shaders are opaque by default. This is the normal use, but it can be useful to have an X-ray vision of

some of them in a special view. So it is possible to adjust global transparency for each shader.

Transparency=0

Transparency=170 Transparency=243

Transparency=255

Material ID parameters: Smoothness

In the “drawer” of the Shader inspector you will find the entire list of materials used in your project.

Select a material and right click on it:

Smoothness=0

Smoothness=0.2

Material ID parameters: Visibility and Shadow casting

In some cases, it is useful to mask a part of the model or to change the shadow processing.

In the sample below, the following settings are applied to the sphere:

Tip: use “Material Cast Shadows” for the grass to disable the radiosity color bleeding:

- On the left, light is bouncing on the green floor and creates green color bleeding on the wall.

- On the right, light goes though the green floor and there is no green color on the wall

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