The sorting step can be complicated. The sorting should be done in eye coordinates, so it is necessary to transform the geometry to eye coordinates in some fashion. If translucent objects interpenetrate, the individual triangles should be sorted and drawn from back to front. Ideally, polygons which interpenetrate should be tessellated along their intersections, sorted, and drawn independently, but this is typically not required to get good results. Frequently only crude or perhaps no sorting at all gives acceptable results.
If there is a single transparent object, or multiple transparent objects which do not overlap in screen space (i.e. each screen pixel is touched by at most one of the transparent objects), a shortcut may be taken under certain conditions. If the objects are closed, convex, and viewed from the outside, culling may be used to draw the backfacing polygons prior to the front facing polygons. The steps are as follows:
Drawing depth buffered opaque objects mixed with translucent objects takes somewhat more care. The usual trick is to draw the background and opaque objects first in any order with depth testing enabled, depth buffer updates enabled, and blending disabled. Next, the translucent objects are drawn from back to front with blending enabled, depth testing enabled but depth buffer updates disabled so that translucent objects do not occlude each other.