This article provides information on the Corona Decal, its settings, and how to use it.
Overview
The Corona Decal is a very convenient way of projecting textures and materials onto your scene objects: graphics, surface imperfections, potholes, all within the 3D viewport and without UVW mapping.
Corona Decal features include:
- Bending in two axes
- Automatic aspect ratio
- Depth and angle projection limits
- Different bump and displacement mixing options
- Affecting only specific material properties (color, roughness, opacity,…)
- ...and more
Ready-made decals are available the Chaos Cosmos browser!
Corona Decals can be used in combination with:
- Chaos Scatter - for scattering a large number of decals
- Corona Multi Shader - for randomizing the appearance of multiple decals
- Corona Mapping Randomizer - for randomizing the mapping of multiple decals
- Corona Front Back Shader - for controlling decal visibility based on front and back face rendering
UI Path: Corona menu > Corona Decal
Object Properties
Mask source
From material – Uses the material's opacity channel used for the decal object as the source mask to cut out the resulting decal.
From shader – Uses a texture map or shader as the source mask (instead of using the opacity channel from the material assigned to the decal) to cut out the resulting decal.
Options
Affect Material – Starting with Corona 10, you can specify which base object(s) material channels a Corona Decal should affect. Both the decal and the base material need to be Corona Physical Materials in order for decal channels to work properly!
The following parameters only work when both the base material and the decal material are Corona Physical materials.
- Affect color – When enabled, the color of the base material is replaced with the decal material color on the geometry where the decal is projected. If disabled, the color of the base material is unaffected.
- Affect specular – When enabled, the specular (IOR, metalness) layer of the base material is replaced with the decal's material specular layer on the geometry where the decal is projected. If disabled, the specular layer of the base material is unaffected.
- Affect roughness – When enabled, the roughness of the base material is replaced with the decal material roughness on the geometry where the decal is projected. If disabled, the roughness of the base material is unaffected.
- Affect opacity – When enabled, the opacity of the base material is replaced with decal material opacity on the geometry where the decal is projected. If disabled, the opacity of the base material is unaffected.
- Affect emission – When enabled, the emission of the base material is replaced with the decal material emission on the geometry where the decal is projected. If disabled, the emission of the base material is unaffected.
- Affect rest – When enabled, the rest of the base material properties (those not specified in before) are replaced with decal material properties on the geometry where the decal is projected. If disabled, these properties of the base material are unaffected.
Displacement – Sets the behavior for the decal's displacement affecting the underlying surface displacement.
- Base only – When selected, the displacement of the base object is preserved unaffected.
- Affect base – When selected, the displacement of the base material is replaced with the decal's material displacement on the geometry where the decal is projected.
- Add to base – When selected, the decal's displacement is added on top of the base material displacement on the geometry where the decal is projected.
The displacement can also be manually adjusted for specific objects by using a Corona Displacement Tag.
Bump – When enabled, the underlying surface bump is overridden by the bump of the material used for the decal object.
- Base only – When selected, the bump of the base object is preserved unaffected.
- Affect base – When selected, the bump of the base material is replaced with the decal's material bump on the geometry where the decal is projected.
- Add to base – When selected, the decal's bump is added on top of the base material bump on the geometry where the decal is projected.
Visible in masks – When enabled, the decal will be visible in the ID Multi-Pass (only if the instance ID option is used).
Size
Width – Allows adjusting the decal's projection width size.
Height – Allows adjusting the decal's projection height size.
Bend - width - Controls the degree of the bend width.
Bend - height - Controls the degree of the bend height.
Fit to Bitmap... – Allows automatically adjusting the decal's width and height according to the proportions of a defined/specific texture map (bitmap).
Projection
Depth limit – Controls the decal object's bounding box depth. In order for the decal to be projected on a surface, the decal's bounding box must intersect the surface.
Max angle limit – Defines the maximum angle at which the projection occurs. If the angle between the Corona Decal and the surface is lower than the specified Max angle limit, the surface receives the projection. This is how the Decal is projected with default settings.
Max angle blur – This value is used to avoid sharp clippings when the Max Angle limit is being used.
Viewport
Show material preview – When enabled, the material used for the decal object is previsualized in the viewport.
Pivot offset – Offsets the decal object's pivot point position.
Examples
Stacking
You can change the arrangement of the Corona Decal objects when using more than one in the same area by simply moving them towards or away from the geometry.
Displacement
Bump
Max angle limit
Max angle blur
Affect Material
In order to affect the underlying surface's opacity, both materials must have the opacity channel enabled (the decal's material and the underlying surface's material)
Bending
Front Back Shader
Corona Decal can be used alongside Corona Front Back Shader to create advanced material effects. This allows for precise control over decals based on front and back face rendering, enabling more flexible material setups.
