#define VectorAdd(a,b,c) ((c)[0]=(a)[0]+(b)[0],(c)[1]=(a)[1]+(b)[1],(c)[2]=(a)[2]+(b)[2])
#define VectorCopy(a,b) ((b)[0]=(a)[0],(b)[1]=(a)[1],(b)[2]=(a)[2])
#define CrossProduct(a,b,c) ((c)[0]=(a)[1]*(b)[2]-(a)[2]*(b)[1],(c)[1]=(a)[2]*(b)[0]-(a)[0]*(b)[2],(c)[2]=(a)[0]*(b)[1]-(a)[1]*(b)[0])
-#define VectorNormalize(v) {float ilength = 1.0f / (float) sqrt(DotProduct(v,v));v[0] *= ilength;v[1] *= ilength;v[2] *= ilength;}
-#define VectorNormalize2(v,dest) {float ilength = 1.0f / (float) sqrt(DotProduct(v,v));dest[0] = v[0] * ilength;dest[1] = v[1] * ilength;dest[2] = v[2] * ilength;}
-#define VectorNormalizeDouble(v) {double ilength = 1.0 / (float) sqrt(DotProduct(v,v));v[0] *= ilength;v[1] *= ilength;v[2] *= ilength;}
+#define VectorNormalize(v) {float ilength = (float) sqrt(DotProduct(v,v));if (ilength) ilength = 1.0f / ilength;v[0] *= ilength;v[1] *= ilength;v[2] *= ilength;}
+#define VectorNormalize2(v,dest) {float ilength = (float) sqrt(DotProduct(v,v));if (ilength) ilength = 1.0f / ilength;dest[0] = v[0] * ilength;dest[1] = v[1] * ilength;dest[2] = v[2] * ilength;}
+#define VectorNormalizeDouble(v) {double ilength = sqrt(DotProduct(v,v));if (ilength) ilength = 1.0 / ilength;v[0] *= ilength;v[1] *= ilength;v[2] *= ilength;}
#define VectorDistance2(a, b) (((a)[0] - (b)[0]) * ((a)[0] - (b)[0]) + ((a)[1] - (b)[1]) * ((a)[1] - (b)[1]) + ((a)[2] - (b)[2]) * ((a)[2] - (b)[2]))
#define VectorDistance(a, b) (sqrt(VectorDistance2(a,b)))
#define VectorLength(a) sqrt(DotProduct(a, a))