/* compute normal vector of given
triangle spanned by the points a, b, c
*/
static void triangle_normal( Vector *a, Vector *b, Vector *c, Vector *out )
{
Vector v1 = *a;
Vector v2 = *a;
vector_sub( &v1, b );
vector_sub( &v2, c );
vector_crossprod( &v1, &v2, out );
}
ErrorCode update_torsional_angle(IndexValue bond, struct ResidueData *residues, IndexValue res, FloatValue *coords)
{
if (residues[res].bonds[bond].type == NOT_SET)
{
return ACCESSING_UNSET_BOND_ERROR;
}
IndexValue atom0, atom1, atom2, atom3;
FloatValue x0, y0, z0;
FloatValue x1, y1, z1;
FloatValue x2, y2, z2;
FloatValue x3, y3, z3;
FloatValue x01, y01, z01;
FloatValue x12, y12, z12;
FloatValue x32, y32, z32;
FloatValue px, py, pz;
FloatValue qx, qy, qz;
FloatValue rx, ry, rz;
FloatValue u, v, u1, v1;
FloatValue a;
atom0 = residues[res].bonds[bond].atom0;
x0 = coords[xcoord_index(atom0)];
y0 = coords[ycoord_index(atom0)];
z0 = coords[zcoord_index(atom0)];
atom1 = residues[res].bonds[bond].atom1;
x1 = coords[xcoord_index(atom1)];
y1 = coords[ycoord_index(atom1)];
z1 = coords[zcoord_index(atom1)];
atom2 = residues[res].bonds[bond].atom2;
x2 = coords[xcoord_index(atom2)];
y2 = coords[ycoord_index(atom2)];
z2 = coords[zcoord_index(atom2)];
atom3 = residues[res].bonds[bond].atom3;
x3 = coords[xcoord_index(atom3)];
y3 = coords[ycoord_index(atom3)];
z3 = coords[zcoord_index(atom3)];
vector_subtract(&x01, &y01, &z01, x0, y0, z0, x1, y1, z1); // v01 = v0 - v1
vector_subtract(&x32, &y32, &z32, x3, y3, z3, x2, y2, z2); // v32 = v3 - v2
vector_subtract(&x12, &y12, &z12, x1, y1, z1, x2, y2, z2); // v12 = v1 - v2
vector_crossprod(&px, &py, &pz, x12, y12, z12, x01, y01, z01); // p = v12 x v01
vector_crossprod(&qx, &qy, &qz, x12, y12, z12, x32, y32, z32); // q = v12 x v32
vector_crossprod(&rx, &ry, &rz, x12, y12, z12, qx, qy, qz); // r = v12 x q
vector_dotprod(&u, qx, qy, qz, qx, qy, qz); // u = q * q
vector_dotprod(&v, rx, ry, rz, rx, ry, rz); // v = r * r
if (u <= 0.0 || v <= 0.0)
{
a = 360.0;
}
else
{
vector_dotprod(&u1, px, py, pz, qx, qy, qz); // u1 = p * q
vector_dotprod(&v1, px, py, pz, rx, ry, rz); // v1 = p * r
u = u1 / sqrt(u);
v = v1 / sqrt(v);
if (fabs(u) > MIN_FLOAT_DIFF || fabs(v) > MIN_FLOAT_DIFF) a = atan2(v, u) * RADIANS_TO_DEGREES;
else a = 360.0;
}
residues[res].bonds[bond].angle = a;
residues[res].bonds[bond].newangle = a;
return NO_ERROR;
}
