What are the pros and cons of using additive, subtractive, and multiplicative blending modes?

1 Additive blending

Additive blending is the simplest and most common blending mode, where the values of each animation layer are added together. This means that the resulting motion is the sum of all the motions in the layers. For example, if you have a base layer of a walk cycle and an additive layer of a head nod, the final animation will show the character walking and nodding at the same time. Additive blending is useful for adding subtle variations, secondary motions, and details to your animation. However, it can also create unwanted effects, such as exaggerated motions, clipping, or drifting, if the layers are not well balanced or synchronized.

2 Subtractive blending

Subtractive blending is the opposite of additive blending, where the values of each animation layer are subtracted from the base layer. This means that the resulting motion is the difference between the base layer and the other layers. For example, if you have a base layer of a walk cycle and a subtractive layer of a head nod, the final animation will show the character walking and nodding less than the base layer. Subtractive blending is useful for reducing or removing motions, such as damping, smoothing, or correcting errors. However, it can also create unnatural or unrealistic effects, such as inverted motions, gaps, or popping, if the layers are not well aligned or matched.

3 Multiplicative blending

Multiplicative blending is a more complex and less common blending mode, where the values of each animation layer are multiplied by the base layer. This means that the resulting motion is the product of all the motions in the layers. For example, if you have a base layer of a walk cycle and a multiplicative layer of a head nod, the final animation will show the character walking and nodding more or less depending on the amplitude of the base layer. Multiplicative blending is useful for creating dynamic and responsive motions, such as modulation, scaling, or adaptation. However, it can also create unpredictable or inconsistent effects, such as distortion, noise, or flickering, if the layers are not well controlled or calibrated.

4 How to choose a blending mode

When choosing a blending mode for your animation, it is important to consider your goals, workflow, and preferences. While there is no definitive answer for which mode is best for each situation, there are some general guidelines that can help you decide. For example, additive blending is great for adding motions that enhance or complement the base layer, like gestures or effects; subtractive blending is ideal for removing motions that interfere or conflict with the base layer; and multiplicative blending is useful for modifying motions that depend on the base layer. Additionally, you should experiment with different modes and parameters to achieve the desired results and test and preview your animation in different contexts to ensure it looks natural and consistent.

5 Blending modes examples

To illustrate the different blending modes and their effects, we can look at some examples of character animation using a simple rig. In each example, there is a base layer of a walk cycle and an additional layer of a head turn. We will apply various blending modes to the head turn layer and observe how it influences the final animation. For instance, when using additive blending for the head turn layer, the character walks and turns his head to the side at the same time, creating a sense of curiosity or interest in his behavior. Subtractive blending results in the character walking and turning his head less than the base layer, evoking a sense of focus or concentration in his behavior. Finally, multiplicative blending enables the character to walk and turn his head more or less depending on the speed of the walk cycle, suggesting adaptation or variation in his behavior.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?