for (int i = 2; i < segCount; i += 2) {
double dx = segments.getQuick(i) - segments.getQuick(i-2);
double dy = segments.getQuick(i+1) - segments.getQuick(i-1);
for (int i = 2; i < segCount; i += 2) {
double dx = segments.getQuick(i) - segments.getQuick(i-2);
double dy = segments.getQuick(i+1) - segments.getQuick(i-1);