.regular = TRUE, .peripheries = 2, .sides = 1};
static polygon_t p_invtriangle = {
.peripheries = 1, .sides = 3, .orientation = 180.0};
-static polygon_t p_invtrapezium = { FALSE, 1, 4, 180., -.4, 0. };
+static polygon_t p_invtrapezium = {
+ .peripheries = 1, .sides = 4, .orientation = 180.0, .distortion = -0.4};
static polygon_t p_invhouse = { FALSE, 1, 5, 180., -.64, 0. };
static polygon_t p_doubleoctagon = { FALSE, 2, 8, 0., 0., 0. };
static polygon_t p_tripleoctagon = { FALSE, 3, 8, 0., 0., 0. };