1. A haptic device comprising: a display configured to display an image; a haptic output device configured to output a haptic effect, the haptic effect configured to simulate a texture of the image or a contour of the image in three dimensions; a processor coupled to the display and the haptic output device; and a memory device including instructions executable by the processor to cause the processor to: detect a movement in one or more directions across a surface of the display; determine a plurality of haptic-effect maps corresponding to the image, each haptic-effect map of the plurality of haptic-effect maps specifying an intensity of the haptic effect at different locations of the display and being associated with a different direction of movement across the surface; and select a haptic-effect map from among the plurality of haptic-effect maps as a function of a direction of the movement across the surface of the display; and modulate the intensity of the haptic effect based on the selected haptic-effect map and the direction of the movement across the surface of the display.