DBL BicubicPatch::determine_subpatch_flatness(const ControlPoints *Patch)
{
int i, j;
DBL d, dist, temp1;
Vector3d n;
Vector3d TempV;
Vector3d vertices[3];
vertices[0] = (*Patch)[0][0];
vertices[1] = (*Patch)[0][3];
TempV = vertices[0] - vertices[1];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
/*
* Degenerate in the V direction for U = 0. This is ok if the other
* two corners are distinct from the lower left corner - I'm sure there
* are cases where the corners coincide and the middle has good values,
* but that is somewhat pathalogical and won't be considered.
*/
vertices[1] = (*Patch)[3][3];
TempV = vertices[0] - vertices[1];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
vertices[2] = (*Patch)[3][0];
TempV = vertices[0] - vertices[1];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
TempV = vertices[1] - vertices[2];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
}
else
{
vertices[2] = (*Patch)[3][0];
TempV = vertices[0] - vertices[1];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
vertices[2] = (*Patch)[3][3];
TempV = vertices[0] - vertices[2];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
TempV = vertices[1] - vertices[2];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
}
else
{
TempV = vertices[1] - vertices[2];
temp1 = TempV.length();
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
}
}
/*
* Now that a good set of candidate points has been found,
* find the plane equations for the patch.
*/
if (subpatch_normal(vertices[0], vertices[1], vertices[2], n, &d))
{
/*
* Step through all vertices and see what the maximum
* distance from the plane happens to be.
*/
dist = 0.0;
for (i = 0; i < 4; i++)
{
for (j = 0; j < 4; j++)
{
temp1 = fabs(point_plane_distance((*Patch)[i][j], n, d));
if (temp1 > dist)
{
dist = temp1;
}
}
}
return (dist);
}
else
{
/*
Debug_Info("Subpatch normal failed in determine_subpatch_flatness\n");
*/
return (-1.0);
}
}
static DBL determine_subpatch_flatness(VECTOR (*Patch)[4][4])
{
int i, j;
DBL d, dist, temp1;
VECTOR n, TempV;
VECTOR vertices[4];
Assign_Vector(vertices[0], (*Patch)[0][0]);
Assign_Vector(vertices[1], (*Patch)[0][3]);
VSub(TempV, vertices[0], vertices[1]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
/*
* Degenerate in the V direction for U = 0. This is ok if the other
* two corners are distinct from the lower left corner - I'm sure there
* are cases where the corners coincide and the middle has good values,
* but that is somewhat pathalogical and won't be considered.
*/
Assign_Vector(vertices[1], (*Patch)[3][3]);
VSub(TempV, vertices[0], vertices[1]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
Assign_Vector(vertices[2], (*Patch)[3][0]);
VSub(TempV, vertices[0], vertices[1]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
VSub(TempV, vertices[1], vertices[2]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
}
else
{
Assign_Vector(vertices[2], (*Patch)[3][0]);
VSub(TempV, vertices[0], vertices[1]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
Assign_Vector(vertices[2], (*Patch)[3][3]);
VSub(TempV, vertices[0], vertices[2]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
VSub(TempV, vertices[1], vertices[2]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
}
else
{
VSub(TempV, vertices[1], vertices[2]);
VLength(temp1, TempV);
if (fabs(temp1) < EPSILON)
{
return (-1.0);
}
}
}
/*
* Now that a good set of candidate points has been found,
* find the plane equations for the patch.
*/
if (subpatch_normal(vertices[0], vertices[1], vertices[2], n, &d))
{
/*
* Step through all vertices and see what the maximum
* distance from the plane happens to be.
*/
dist = 0.0;
for (i = 0; i < 4; i++)
{
for (j = 0; j < 4; j++)
{
temp1 = fabs(point_plane_distance(((*Patch)[i][j]), n, &d));
if (temp1 > dist)
{
dist = temp1;
}
}
}
return (dist);
}
else
{
/*
Debug_Info("Subpatch normal failed in determine_subpatch_flatness\n");
*/
return (-1.0);
}
}