Application of Algorithm:

If the algorithm given earlier is applied to the four polygons at first named (say) as PQR, PQS, PRS, and QRS, we obtain :

i = 1 : PQR chosen accurately. Confirm, k = 6 > 0, visible, plot.

i = 2 : j = 1 : PQS (P) versus PQR (P), PQ-PQ straight match, reverse PQS to SQP.

k = - 5, < 0, not visible. (First vertex repeated at end, illustrated in brackets.)

i = 3 : j = 1 : PRS (P) versus PQR (P), PR-RP reverse match, keep PRS as is.

k = - 3, < 0, not visible.

i = 4 : j = 1 : QRS (Q) versus PQR (P), QR-QR straight match, reverse QRS to SRQ.

k = 2, > 0, visible, plot.

Therefore, faces PQR and SRQ are visible, and the other two faces PQS and PRS are hidden, as already illustrated.

The computer algorithm checks one face at a time, and plots the edges and fills in the area just if the k coefficient is positive. If it is desired to show the hidden edges in broken lines (or with thinner lines or lighter colour), the algorithm may plot the edges of the hidden polygons first as broken (or thinner or lighter) lines, without filling in the areas and then plot the visible edges and faces, so that the visible edges shall overlap the earlier hidden-coded line rendering at the common edges.