A head mounted display (HMD) adjusts the phase of light of a virtual scene using a spatially programmable focusing element. Depths of the virtual scene are approximated to one or more focal surfaces and the shape of the focal surfaces is then adjusted to minimize the distance of the focal surface to features in the virtual scene. The resulting shape of the focal surface is a continuous piecewise smooth three-dimensional curve. A phase function is generated for each focal surface that, when executed by the spatially programmable focusing element, reproduces a focal pattern corresponding to the each focal surface, which bends and shapes the wavefront to produce a focal pattern that conforms to the scene geometry.