Such lines can be used to add depth to an image. Perspective drawing is based on the fact that parallel lines appear to converge to a vanishing point in an image. Realistic styles of art use converging lines to add a convincing third dimension to a flat image. Curved Lines Curved lines add a natural feel to images. They can be used to convey humor and warmth in even simple compositions.
Cartoons strips are great examples of the power of curves to express so much with very few lines.
Trends in art history have shifted often between preferences for straight and curved lines. Perspective drawing flourished during the Renaissance with its mathematically precise lines. The Baroque period celebrated buxom beauties with plenty of curves. This century gave us the Cubists who viewed all forms as collections of straight lines. Today, fractal designers mathematically deny the very idea of a straight line.