Appearance Functions

The following table outlines all appearance functions in the Appearances library:

• Some functions cannot be assigned to parts directly. If the right-click context menu options are unavailable from the appearance thumbnail, or the context menu does not open when the appearance thumbnail is dragged and dropped on the part in the scene, this indicates the appearance is a function.

• See Appearance library - Functions for a complete list of all functions and a short description of each.

• Some functions can only be applied to parameters in the Appearance panel, and depend on what is selected in the Scene list.

• For the Normal map — texture function, texture resources can optionally be treated as containing linear color data. When the texture represents something other than a color (for example a tangent space normal map or scalar data such as roughness) then it should be treated as linear to ensure the color data is correctly processed.

  For normal map textures specifically, the Linear option is automatically selected to ensure valid results. For other parameters you can choose how you want to interpret the colors using the Linear options on the context menu for the texture resource (see below):

  

• To apply an Appearance function to an Appearance parameter while the Appearances library is in the right panel, drag the Appearance function on top of the Appearance panel icon and hold until it opens. Then drop the Appearance function on the parameter in the panel.

  

  Dragging the Bump map Appearance function over the Appearance panel icon (left). The Appearance panel opens (middle). While still holding, drag the Bump map Appearance function on top of the Bumps parameter in the Appearance panel (right).

To apply a function to the part's Appearance parameter:

1. Select the part in the Scene list or graphics area. The Appearance panel displays the part's default Appearance parameters.

2. Select the Appearance functions folder In the Appearances library

   

   Locate the Checker pattern — 3D texture and Checker texture bump map functions. They are both used in this example. The lower box part in the following model is used for reference:

   

3. Drag the Checker pattern — 3D texture function over the Appearances panel. Before dropping, notice that many of the Appearance parameters are highlighted in blue. This indicates this function can be applied to any of these parameters. The function is applied to the parameter beneath the mouse cursor. Drop the parameter on the Transmission weight parameter in the Transmission submenu:

   

4. The texture function is applied and automatically opens in the Appearances panel. This is verified by viewing the hierarchical breadcrumb trail at the top of the Appearances panel (shown in the first image below). Click on the Appearance 2 link in this breadcrumb trail, and the Appearance for the part opens, where the link to the texture function next to the Transmission weight parameter is displayed (shown in the second image below).

   

5. The texture function acts as a mask for light transmission through the part (the checker texture is the function applied to the Transmission weight parameter of the part's Appearance). Anywhere the checker pattern is white, light shows through. Anywhere the checker pattern is black, the base part color shows through. The checker pattern is the part's light transmission mask:

   

6. Alternatively, drop the Checker texture bump map function on the Bumps parameter in the Appearance panel's Global submenu. The Bumps parameter is the only one to turn blue, indicating this parameter is the only one that accepts the Checker texture bump map function:

   

7. The Checker texture bump map function is applied to the Bumps parameter, shown below:

   

See Add a bump texture and Add a custom bump texture for more information.

The next example applies an Invert color function to the Part's base color. Apply this method to any appearance color parameter, and use it to invert the color.

1. Select the part. In this example, the sphere is selected.

2. Drag and drop the Invert color function on the Base color in the part's Base submenu on the Appearance panel:

   

3. The Invert color function opens under the Appearance panel. Click the Input color swatch and select a color. The inverse of that color is used for the Part's base color. In the following example, selecting red creates a cyan base color, since cyan is the inverse of red:

   

This example uses the Surface blender function to blend between two surface appearances. Once completed, an additional function (Gradient3-color/position texture) is applied to the first function's parameter (the Surface blender's Blend weight). This shows how to build one function on top of another function.

1. Select the part in the Scene list. In this example a square box is selected and viewed from the top plane. For reference, the box dimensions are .5 m length x .5 m width x .5 m height:

   

2. In the Appearance library, search for Surface. Right-click on the Surface blender thumbnail and click Assign (shown in the first image below). The Global submenu in the Appearance panel displays the Surface blender function parameters (second image below):

   

   • Base material - The appearance on which the blend is based.

   • Blend material - Blend appearance surface properties.

   • Blend weight - Blend weight or mask texture.

3. Search for the Metal weave 02 - brass steel Appearance and drag and drop the thumbnail on the Base material parameter (shown in the first image below). Then search for the Metal weave 02 - copper pure Appearance and drag and drop the thumbnail on the Blend material parameter (shown in the second image below). Adjust the Blend weight to 1. This blends the colors between the two appearances (the Base material and the Blend material). The result is shown in the third image below:

   

   

4. Click on the blend material link to open its parameters in the Appearance panel (shown in the first image below). Rotate the material 90 degrees in the Adjustments submenu. The horizontal pattern is now combined with the newly rotated vertical pattern (shown in the second image below). This better visualizes the blend between the two:

   

5. To return to the parent Surface blender layer, click the Surface blender link in the breadcrumb trail at the top of the Appearance panel:

   

The above procedure works to blend any two surface appearances together. Building on the above procedure, a gradient function is applied to the Surface blender function's Blend weight parameter to blend between the two appearances.

1. Open the 2 Appearances and change their Weave and bar colors to the following: red and green for the Base material, and blue and yellow for the Blend material. This better visualizes the blends in subsequent steps. The result is shown in the second image below:

   

2. Return to the parent Surface blender layer. Search for the Gradient 3-color/position texture function in the Appearance library, and then drag and drop the thumbnail on the Blend weight parameter.

   

3. The Gradient 3-color/position texture function is now applied to the Blend weight of the Surface blender function's parameter. The gradient is used as a mask between the Base material red and green colors (starting on the left) and the Blend material's blue and yellow colors (ending on the right). Where the gradient is black, the Base material shows through. Where the gradient is white, the Blend material shows through.

   Altering the Gradient parameters produces a variety of gradient results that blend between the two appearances. For example, the image below displays the Mode: Gradient box option (shown in the second image below):

   

Notes

• To blend between two colors, use the Blend colors function and apply it wherever a color parameter is available in the Appearance or Selection panel. Using the blend colors function opens access to layer blending modes that are found in applications like Adobe Photoshop and GIMP (darken, screen, multiply, overlay, and others).

• To blend between two bump textures, use the Blend normals function and apply it wherever the Bumps parameter is available in the Appearance or Selection panel.

• Instead of the Gradient 3-color/position texture function, use any other texture functions, such as the Checker pattern or Bump map — Perlin noise texture to blend between the two appearances.

• Add a custom texture to blend between the two appearances. Drag and drop the Import bitmap file function on the Blend weight parameter (shown in the first image below), and then Click the Bitmap file to open the Select image dialog, where you can load the custom texture (shown in the second image below):

  

For a tech tip on blends, see Using textures and blends in Render Studio.

This procedure explains how to add a specific volume and the Volume coefficient function to a part in the scene. Volume is added as an appearance to the part, while the volume coefficient is a function added to the Absorption coefficient parameter of the appearance.

For this example, a light-emitting ship object is placed in an underwater scene where the water acts as the volume.

1. To add volume, the scene must be encompassed by the volume itself. Model a part that surrounds the ship object on all sides, and is large enough to provide sufficient space.

   For reference, the surrounding box in this example is 5 m cubed. The rectangular "ship" is 0.6 m length by 0.075 m wide by 0.05 m height. A hole is placed at the front bottom of the rectangle with a diameter of 0.025 and is 0.03 m deep so it does not protrude all the way through the rectangle. Finally, a sphere with a radius of 0.004 m is created inside the hole, which is used as a light source. Each entity (part) is referenced as volume, ship, and light source below.

   

2. In the Scene list, select the volume part. Search for volume in the Appearances library, right-click on the Add volume thumbnail and select Assign from the context menu. This results in a thick volumetric appearance applied to the surrounding part:

   

The following outlines the Add volume Appearance panel parameters:

• Base material - The material onto which the volume is applied. Default is transparent.

• Absorption coefficient - The probability density (per meter in world space) of light being absorbed by the participating medium. Default is white (R: 255; G: 255; B: 255). A higher absorption value makes the medium darker, due to more of the light being absorbed as it passes through the medium.

• Scattering coefficient - The probability density (per meter in world space) of light being scattered from its current direction. The default is white (R: 255; G: 255; B: 255). A higher scattering value distributes more of the light throughout the medium.

• Directional bias - Influence of light direction on scattering. A value of 0 specifies isotropic scattering, 1 forward scattering, and −1 back scattering. The default is 0.

3. In the Appearances Library > Appearance functions folder, locate, and then drag and drop the Volume coefficient function on top of the Absorption coefficient parameter in the Appearance panel (shown below left). Then adjust the Tint parameter to R: 139; G: 179; B: 198 (shown below right). This creates a volume of water that contains the ship.

   

4. Click the Transparent link next to the Base Material parameter, and adjust the Transmission color to R: 189; G: 208; B: 231, as shown below:

   

5. At the top of the Appearance panel, click the Add volume link to return to the volume parameters. Set the Directional bias to 0.7. This lightens the scene, so the ship is visible inside the water:

   

6. In the Scene list, deselect the volume part and select the ship part. Locate the Metal — Scuffed oxidized steel Appearance in the Appearance library, right-click on the thumbnail and select Assign from the context menu (shown below left). In the Appearance panel, adjust the following parameters: Scale: X: 2 by Y: 2; Rust bump strength: 0.4; Rust amount: 0.1; Rust reflection roughness: 0.5; Reflection roughness: 1:

   

7. In the Scene list, deselect the ship part and select the light part. Locate the Spot light Appearance in the Appearance library, right-click on the thumbnail and select Assign from the context menu (shown below left). Zoom into the ship to view it from the bottom up. The light is illuminated but is very faint (shown below right):

   

   Spot light parameters are:

   

   • Emission color - Light color. This is rescaled such that it does not influence the luminous flux. The default is white (R: 255; G: 255; B: 255).

   • Flux - The total luminous flux (in lumen) the light emits. The default value is 500. It is generally required to increase this value, depending on the scene.

   • Scene unit size - Convert m to scene unit. For example, if 1 in the scene is one foot (US customary units), then the scene unit size is 0.30481. The default value is 1.

   • Spot exponent - The higher the exponent, the more focused the emission. The default value is 0.

   • Spread angle - Spread angle in RAD. Hard limit for the spot spread. The default value is 6.283.

   • Two sided emission - If enabled, emission occurs on the front and backside of the geometry. The default is disabled.

8. Set the Flux to 20000 and Scene unit size to 0.8. The light now emits a higher intensity light, and is diffuse and unfocused:

   

9. To focus the light to a narrower beam, set the Spot exponent to 15 and Spread angle to 2.5:

   

10. To have the light color blend in with the water, alter the Emission color to R: 157; G: 189; B: 226. Bear in mind that any of these parameters can be adjusted to different specifications. This is one variation on the scene render: