Function vm_GetPerp

vecmat/vector.cpp:209–219

Calculates the perpendicular vector given three points Parms: n - the computed perp vector (filled in) v0,v1,v2 - three clockwise vertices

// Parms:	n - the computed perp vector (filled in)
//			v0,v1,v2 - three clockwise vertices
void vm_GetPerp(vector *n, vector *a, vector *b, vector *c) {
  // Given 3 vertices, return the surface normal in n
  // IMPORTANT: B must be the 'corner' vertex

  vector x, y;

  vm_SubVectors(&x, b, a);
  vm_SubVectors(&y, c, b);

  vm_CrossProduct(n, &x, &y);
}

// Calculates the (normalized) surface normal give three points
// Parms:	n - the computed surface normal (filled in)