In computer graphics and animation, both morphing and tweening are techniques used to create smooth transitions between different states or shapes. The primary distinction lies in the complexity of the transformation involved, particularly concerning the geometric properties of the shapes being transitioned.
Understanding the Core Distinction
Based on the provided reference, the key difference is:
- Shape Tweening: This technique is used to create a smooth transition between two shapes that have the same number of points and segments.
- Morphing: This is used to create a smooth transition between two shapes that have different numbers of points and segments, or even between different types of shapes altogether.
In essence, tweening is a simpler form of interpolation applied when the underlying structure of the start and end shapes is identical. Morphing handles more complex transitions where the structure changes significantly.
Key Differences in Detail
Here's a breakdown comparing morphing and tweening:
| Feature | Shape Tweening | Morphing |
|---|---|---|
| Shape Structure | Requires shapes with the same number of points and segments. | Can transition between shapes with different numbers of points and segments. |
| Shape Types | Typically used for transitions between identical shape types (e.g., circle to circle, square to square). | Can transition between different shape types (e.g., circle to square, text to an image outline). |
| Complexity | Relatively simpler; interpolates existing points/segments. | More complex; often requires algorithms to add/remove points or redistribute existing ones during the transition. |
| Application | Smooth shape resizing, rotation, or deformation without changing fundamental structure. | Creating visually dramatic transformations between disparate objects. |
When to Use Each Technique
Choosing between morphing and tweening depends on the nature of the shapes you are transitioning between:
- Use Shape Tweening when:
- You are animating a single shape changing size, position, or simple deformation.
- Both the starting and ending shapes are variations of the same object, maintaining the same number of vertices or control points.
- Examples: A circle growing larger, a square rotating, a simple blob changing shape slightly while keeping the same number of points.
- Use Morphing when:
- You are transitioning between two completely different shapes.
- The number of points or segments in the starting shape is different from the ending shape.
- You want to transform one type of object into another, visually appearing to "morph" into something new.
- Examples: Transforming a circle into a square, making a word dissolve into a bird shape, changing a face into another face (often called face morphing).
While the term "morphing" is sometimes used casually to describe any smooth shape transition, the technical distinction, especially in animation software, often comes down to whether the underlying structure (point/segment count) of the shapes matches.
