1. A drawing apparatus comprising: a dividing unit dividing a rectangle frame circumscribing a triangle displayed on a display screen into a plurality of rectangle segments; a determining unit sequentially performing a determining process of determining whether each rectangle segment included in the rectangle frame overlaps the triangle in a predetermined direction and outputting a determination result of overlap or nonoverlap; a determination control unit ending the determining process in the predetermined direction if the determination result output from the determining unit changes from the overlap to the nonoverlap; and drawing unit performing a drawing process on the rectangle segment determined to overlap the triangle by the determining unit.