public ColorRGBA add(ColorRGBA c) {
        return new ColorRGBA(c.r + r, c.g + g, c.b + b, c.a + a);
    }
Adds each r,g,b,a of this <code>ColorRGBA</code> by the corresponding
r,g,b,a of the given color and returns the result as a new <code>ColorRGBA</code>.
Used as a way of combining colors and lights.

@param c The color to add.
@return The new <code>ColorRGBA</code>.  this+c
jme3-core/src/main/java/com/jme3/math/ColorRGBA.java