- Base Color
- Use Vertex Color?
- Show Volume
- Strength
- Advanced Volume Colors
- Blend Modes
- Basic Blend Modes
- Advanced Blend Modes
- Non-Commutativity [NC]
Base Color
The Base Color defines the main color of the Stencil Lights or Shadows effect.
Each Blend Mode will use the Base Color differently, but you can generally expect the final color to be a lightening or a darkening effect tinted with the Base Color. The alpha channel is ignored, except for some advanced blending modes under “Alpha Blending”. The intensity of the effect is usually set by the brightness of the Base Color.
Use Vertex Color?
Enable this option to use the vertex color of each rendered mesh as the base color for the effect.
For performance, we suggest using the least number of materials in your scene. If you have several different colors, performance can be improved by using the vertex color option and encoding the color information in the mesh, so you can have a single material rendering all stencil effects in your scene.
If you are using ProBuilder (not included with Stencil Lights and Shadows) you can easily change mesh vertex colors using the “Vertex Colors Editor” tool. This is very useful to quickly iterate the visuals of multiple objects.
For more information, visit https://unity.com/features/probuilder
Show Volume
“Show Volume” enables rendering of the volume of the mesh in addition to the main effect. The rendered volume always uses the same blend mode as the main effect,
You can customize the color that is used as the base color for the volume rendering. Enable “Advanced Volume Color” for more option on how to control the color of the volume effect.
Strength
“Strength” controls the intensity of the volume color in comparison to the Base color.
Case | Description |
Strength = 0 | Keeps the same color as the Base Color |
Strength > 0 | Increases the intensity of the effect (lights get lighter, shadows get darker) |
Strength < 0 | Decreases the intensity of the effect (lights get darker, shadows get lighter) |
Advanced Volume Colors
Advanced Volume Color provides different modes for adjusting the color of the volume, usually using the base color of the effect as a starting point for the calculation. For formulas, each color channel (RGB) is calculated independently.
- Result = the final RGB color that will be used for the volume effect
- Base Color = the RGB of the Base Color of the Stencil Lights and Shadows (the main effect)
- Volume Color = the RGB provided as operand in the show volume option
Blend Modes
Basic Blend Modes
Blend modes affect how the final color of the effect will be rendered. There are two basic blend modes, which were designed to be simple to use:
Both “Light” and “Shadow” blend modes are commutative, which means that when stacked on top of themselves the result is independent of rendering order, resulting in no z-fighting. This property is not true for some of the advanced blend modes, as noted below.
Mode | Description |
Light | Lightens the surrounding geometry with its intensity defined by the base color, creating the impression of a stylized light. This is the exact same effect as the Advanced Blending mode named “Screen”, which is also known as “Soft Additive”. |
Shadow | Darkens the surrounding geometry with its intensity defined by the base color, creating the impression of a stylized shadow. This is the exact same effect as the Advanced Blending mode named “Multiply”. |
Advanced Blend Modes
There are sixteen advanced blend modes, divided into six different categories.
*Difference is slightly different from the conventional Difference blend mode found in traditional image editing software. It does NOT take the absolute value of the difference. As a result, this blending mode is non-commutative, which differs from the conventional implementation.
Formulas are described using the following notation:
- Result = the final RGB color that will be rendered
- Base = the RGB of the Base Color of the Stencil Lights and Shadows
- Alpha = the alpha channel of the Base Color of the Stencil Lights and Shadows
- Background = the RGB color of the background behind the Stencil Lights and Shadows
- 1 = (1,1,1) = White
- 0 = (0,0,0) = Black
Colors cannot have values below zero or above one (they will be clamped accordingly). Divisions by zero result in undetermined behavior and should be avoided.
Color channels (R, G, B) are calculated independently to produce the result color. The blend mode specified applies both to the main effect of Stencil Lights and Shadows and to the effect rendered by the “Show Volume” option.
Category | Broad Description |
Normal | No blending |
Lighten | Final color is lighter than original |
Darken | Final color is darker than original |
Hybrid | Darkens or lightens |
Inversion | Inverts colors and/or creates stylized effects |
Alpha Blending | Uses the alpha channel to blend |
Non-Commutativity [NC]
Blend modes that are non-commutative require more caution when used.
When overlapping two meshes with the same blending mode that in non-commutative, the result will be dependent on draw order. This can result in image artifacts “popping in and out” and z-fighting, which is often undesirable.
To mitigate this, you can either:
- Ensure that no Stencil Lights and Shadows overlap.
- Or use different materials for each Stencil Lights and Shadows, each with a distinct Render Queue value (this can be done in the Material Inspector itself)
| Name | Commutativity | Category | Formula |
|---|---|---|---|
Non-Commutative [NC] | Normal | RESULT = BASE | |
Commutative | Lighten | RESULT = MAX (BASE, BACKGROUND) | |
Commutative | Lighten | RESULT = 1 - (1-BASE) * (1-BACKGROUND) | |
Non-Commutative [NC] | Lighten | RESULT = BACKGROUND / (1-BASE) | |
Commutative | Lighten | RESULT = BASE + BACKGROUND | |
Commutative | Darken | RESULT = MIN (BASE, BACKGROUND) | |
Commutative | Darken | RESULT = BASE * BACKGROUND | |
Non-Commutative [NC] | Darken | RESULT = 1 - (1-BACKGROUND) / BASE | |
Commutative | Darken | RESULT = BACKGROUND + BASE - 1 | |
Commutative | Hybrid | RESULT = 2 * BASE * BACKGROUND | |
Non-Commutative [NC] | Inversion | RESULT = BASE - BACKGROUND | |
Non-Commutative [NC] | Inversion | RESULT = BASE + BACKGROUND – 2 * BASE * BACKGROUND | |
Non-Commutative [NC] | Inversion | RESULT = BACKGROUND - BASE | |
Non-Commutative [NC] | Inversion | RESULT = BACKGROUND / BASE | |
Non-Commutative [NC] | Alpha Blending | RESULT = (BASE * ALPHA) + (BACKGROUND * (1-ALPHA)) | |
Non-Commutative [NC] | Alpha Blending | RESULT = BASE + BACKGROUND * (1-ALPHA) |