You can use the Interactive Mesh Fill Tool (Figure 10.40) to add gradual color or shading to objects.
The Interactive Mesh Fill Tool works by superimposing a grid on a selected object. The intersection points of this grid are joined with nodes that can be manipulated with the Shape Tool. You can add color to the grid that radiates out from a node or a patch (any discrete area of the grid).
Select the Interactive Mesh Fill Tool from the Interactive Fill flyout in the toolbox (Figure ...