Game Programming Using Qt

Time for action – rotating an item

As an example, let's rotate itemB and itemC by 45 degrees counter-clockwise. For itemB, the function call would look like this:

itemB->setRotation(-45);

The setRotation() function accepts qreal as the argument value, so you can set very precise values. The function interprets the number as degrees for a clockwise rotation around the z coordinate. If you set a negative value, a counter-clockwise rotation is performed. Even if it does not make much sense, you can rotate an item by 450 degrees, which would result in a rotation of 90 degrees. Here is what the two items would look like after the rotation by 45 degrees counter-clockwise:

What just happened?

As you can see, the rotation has its center in the item's origin ...