Shape Morphing and Motion Paths in LibreOffice Impress

LibreOffice Impress provides native tools to animate vector graphics along custom motion paths and morph shapes using intermediate transformation techniques. This guide covers the specific vector animation effects available in Impress, how to configure custom motion paths, and how to use the cross-fading feature to achieve shape-morphing animations for dynamic presentations.

Motion Path Animations

Motion paths allow any vector graphic, text box, or shape to move across a slide along a predetermined or custom-drawn trajectory.

Predefined Motion Paths

Impress includes a variety of built-in motion path trajectories accessible via the Animation panel in the right sidebar: * Basic Movements: 2-Point Line, 4-Point Star, 5-Point Star, 8-Point Star, Circle, Heart, Hexagon, Octagon, Pentagon, and Square. * Complex Trajectories: Spiral, S-Curve, Zigzag, Sine Wave, Spring, Loop, and Figure 8.

Custom Motion Paths

You can draw custom trajectories to move vector objects precisely across the slide: 1. Select the vector object on your slide. 2. Open the Animation deck in the sidebar and click the Add Effect (+) button. 3. In the Category dropdown, select Motion Paths. 4. Choose Curve, Polygon, or Freeform. 5. Draw the path directly on the slide canvas. Double-click to complete the path.

Editing and Fine-Tuning Paths

Once applied, motion paths behave like editable vector curves: * Edit Points: Select the motion path and toggle Points mode (F8) to add, delete, or adjust Bézier control handles for smooth curve transitions. * Reversal: Right-click the path to reverse the direction of the movement. * Timing and Easing: Open Effect Options to control duration, delay, repeat count, and set smooth acceleration (Smooth Start) or deceleration (Smooth End).

Vector Shape Morphing (Cross-Fading)

While Impress does not have an automatic single-click morph transition like some proprietary tools, it features a vector Cross-fading tool that calculates geometric and color transitions between two vector objects.

How Cross-Fading Works

Cross-fading generates intermediate vector shapes that blend the starting shape’s geometry, fill color, and border into the ending shape.

  1. Draw the starting vector shape (e.g., a circle) and the destination vector shape (e.g., a star) on the slide.
  2. Select both shapes simultaneously using the Shift key.
  3. Go to the menu and select Shape > Cross-fade (or Edit > Cross-fade depending on your interface layout).
  4. Configure the settings:
    • Increments: Set the number of intermediate shapes (e.g., 5 to 15 steps for smooth blending).
    • Cross-fade color: Check this option to blend colors progressively.
    • Same orientation: Keeps alignment steady during the transformation.
  5. Click OK to generate the intermediate vector objects.

Converting Cross-Fades into Smooth Morph Animations

To turn the generated cross-fade steps into an animated sequence: 1. Select all the generated intermediate shapes. 2. Open the Animation panel and assign an Appear entrance effect with a very fast duration (e.g., 0.05 to 0.1 seconds per frame). 3. Set the start trigger to After Previous for each frame in sequence. 4. Align all generated shapes directly on top of each other using Shape > Align > Centered and Shape > Align > Middle to produce a frame-by-frame vector morph.

Combining Paths and Vector Transformations

To create complex presentations, vector objects can combine multiple animation types: * Convert to Curves: Convert basic shapes to curves via Shape > Convert > To Curve to manipulate points before applying animations. * Simultaneous Effects: Combine a Motion Path with a Spin or Grow/Shrink animation by setting both effects to start With Previous.