bool Triangle::Compute_Triangle()
{
int swap;
Vector3d V1, V2, Temp;
DBL Length;
V1 = P1 - P2;
V2 = P3 - P2;
Normal_Vector = cross(V1, V2);
Length = Normal_Vector.length();
/* Set up a flag so we can ignore degenerate triangles */
if (Length == 0.0)
{
Set_Flag(this, DEGENERATE_FLAG);
return(false);
}
/* Normalize the normal vector. */
Normal_Vector /= Length;
Distance = dot(Normal_Vector, P1);
Distance *= -1.0;
find_triangle_dominant_axis();
swap = false;
switch (Dominant_Axis)
{
case X:
if ((P2[Y] - P3[Y])*(P2[Z] - P1[Z]) <
(P2[Z] - P3[Z])*(P2[Y] - P1[Y]))
{
swap = true;
}
break;
case Y:
if ((P2[X] - P3[X])*(P2[Z] - P1[Z]) <
(P2[Z] - P3[Z])*(P2[X] - P1[X]))
{
swap = true;
}
break;
case Z:
if ((P2[X] - P3[X])*(P2[Y] - P1[Y]) <
(P2[Y] - P3[Y])*(P2[X] - P1[X]))
{
swap = true;
}
break;
}
if (swap)
{
Temp = P2;
P2 = P1;
P1 = Temp;
}
/* Build the bounding information from the vertices. */
Compute_BBox();
return(true);
}
int Compute_Triangle(TRIANGLE *Triangle,int Smooth)
{
int swap,degn;
VECTOR V1, V2, Temp;
DBL Length;
VSub(V1, Triangle->P1, Triangle->P2);
VSub(V2, Triangle->P3, Triangle->P2);
VCross(Triangle->Normal_Vector, V1, V2);
VLength(Length, Triangle->Normal_Vector);
/* Set up a flag so we can ignore degenerate triangles */
if (Length == 0.0)
{
Set_Flag(Triangle, DEGENERATE_FLAG);
return(false);
}
/* Normalize the normal vector. */
VInverseScaleEq(Triangle->Normal_Vector, Length);
VDot(Triangle->Distance, Triangle->Normal_Vector, Triangle->P1);
Triangle->Distance *= -1.0;
find_triangle_dominant_axis(Triangle);
swap = false;
switch (Triangle->Dominant_Axis)
{
case X:
if ((Triangle->P2[Y] - Triangle->P3[Y])*(Triangle->P2[Z] - Triangle->P1[Z]) <
(Triangle->P2[Z] - Triangle->P3[Z])*(Triangle->P2[Y] - Triangle->P1[Y]))
{
swap = true;
}
break;
case Y:
if ((Triangle->P2[X] - Triangle->P3[X])*(Triangle->P2[Z] - Triangle->P1[Z]) <
(Triangle->P2[Z] - Triangle->P3[Z])*(Triangle->P2[X] - Triangle->P1[X]))
{
swap = true;
}
break;
case Z:
if ((Triangle->P2[X] - Triangle->P3[X])*(Triangle->P2[Y] - Triangle->P1[Y]) <
(Triangle->P2[Y] - Triangle->P3[Y])*(Triangle->P2[X] - Triangle->P1[X]))
{
swap = true;
}
break;
}
if (swap)
{
Assign_Vector(Temp, Triangle->P2);
Assign_Vector(Triangle->P2, Triangle->P1);
Assign_Vector(Triangle->P1, Temp);
if (Smooth)
{
Assign_Vector(Temp, ((SMOOTH_TRIANGLE *)Triangle)->N2);
Assign_Vector(((SMOOTH_TRIANGLE *)Triangle)->N2, ((SMOOTH_TRIANGLE *)Triangle)->N1);
Assign_Vector(((SMOOTH_TRIANGLE *)Triangle)->N1, Temp);
}
}
degn=true;
if (Smooth)
{
degn=compute_smooth_triangle((SMOOTH_TRIANGLE *)Triangle);
}
/* Build the bounding information from the vertices. */
Compute_Triangle_BBox(Triangle);
return(degn);
}
