Refractions can be rendered with techniques similar to those presented for reflections. For example, with planar refractors, rather than reflecting the original scene about the mirror plane, translate and rotate the original scene to match the refracted viewpoint.
Refractions may be rendered using the same stencil masking and texture projection techniques described for reflections.
Refractions from a curved object can be rendered using an extension of the explosion map technique shown above, in which refraction directions are mapped to a 2D space instead of reflection directions.
Light rays converge through some curved refractors and diverge through others. Refractors which exhibit both behaviors must be partitioned into separate objects in the same way that concave and convex refractors are partitioned as discussed in Section 11.1.3.