In this tutorial, we will explore how to use the tweening tool to create an animation in which a circle evolves into a star and moves across the screen. This will introduce all the basic techniques of tween animation.
The first step is to launch Opus Pro and create a blank new publication. If you want to create tween animations for output to Flash then select the Opus Flex publication type. In our example we have also changed the publication size to 450 x 120 as it better suits our requirements (this is set in Chapter Properties).
TIP: We recommend that all initial editing of the objects you want to use in your tween (e.g: setting the colour, adding and deleting elements including nodes etc) takes place before putting the object in the tween, and certainly before adding any keyframes.
So let's create our circle object before we create the tween object... Click on the vector drawing tool and choose the Circle/Ellipse tool from the flyout menu.
Draw a circle anywhere towards the left of the page and to whatever size you like bearing in mind that you will want space to create the rays of the star. Remember to hold down the Alt key when you draw so that you create a circle rather than an oval. In our example we have chosen red as the fill colour and a darker red as the outline colour and we have given the object a more descriptive name of starcircle.
We shall be tweening the nodes of the circle to create a star shape but if you select the node editing tool from the vector tool bar you will note that the circle has only four nodes and we will need more than that to create the spikes of the star.
TIP: Node tweening requires the same number of nodes at all points in the tween. If you add or delete nodes at keyframes in the tween it can lead to unexpected results.
Move the node editing cursor to the object and click and drag to select all the nodes in the circle.
Then click the Add Node button to insert nodes between those selected.
Repeat the two steps above to select all nodes and then add nodes to insert nodes between each of the new nodes so that you end up with 16 nodes spaced evenly around the circle.
In the next part of the tutorial, we will add the object to the tween and add keyframes to create animtion.