Vec addvec(Vec, Vec);
Vec subvec(Vec, Vec);
Vec mulvec(Vec, double);
double dotvec(Vec, Vec);
Point centroid(Triangle);
void triangle(Image *, Triangle, Image *, Point);
void filltriangle(Image *, Triangle, Image *, Point);
Triangle gentriangle(void);
Triangle rotatriangle(Triangle, double);
Triangle inrotatriangle(Triangle, double);
void *emalloc(ulong);
Point tobase(Point);