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add mathutils function to intersect 2 circles. Converted to C from a python script by Alex Fraser.

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Campbell Barton 2013-01-28 11:52:17 +00:00
parent 9b2c0f03dd
commit f44b7868c5
1 changed files with 81 additions and 0 deletions
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81
source/blender/python/mathutils/mathutils_geometry.c
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@ -251,6 +251,86 @@ static PyObject *M_Geometry_intersect_line_line(PyObject *UNUSED(self), PyObject
}
}
/* Line-Line intersection using algorithm from mathworld.wolfram.com */
PyDoc_STRVAR(M_Geometry_intersect_sphere_sphere_2d_doc,
".. function:: intersect_sphere_sphere_2d(p_a, radius_a, p_b, radius_b)\n"
"\n"
" Returns 2 points on between intersecting circles.\n"
"\n"
" :arg p_a: Center of the first circle\n"
" :type p_a: :class:`mathutils.Vector`\n"
" :arg radius_a: Radius of the first circle\n"
" :type radius_a: float\n"
" :arg p_b: Center of the second circle\n"
" :type p_b: :class:`mathutils.Vector`\n"
" :arg radius_b: Radius of the second circle\n"
" :type radius_b: float\n"
" :rtype: tuple of :class:`mathutils.Vector`'s or None when there is no intersection\n"
);
static PyObject *M_Geometry_intersect_sphere_sphere_2d(PyObject *UNUSED(self), PyObject *args)
{
PyObject *ret;
VectorObject *vec_a, *vec_b;
float *v_a, *v_b;
float rad_a, rad_b;
float v_ab[2];
float dist;
if (!PyArg_ParseTuple(args, "O!fO!f:intersect_sphere_sphere_2d",
&vector_Type, &vec_a, &rad_a,
&vector_Type, &vec_b, &rad_b))
{
return NULL;
}
if (BaseMath_ReadCallback(vec_a) == -1 ||
BaseMath_ReadCallback(vec_b) == -1)
{
return NULL;
}
ret = PyTuple_New(2);
v_a = vec_a->vec;
v_b = vec_b->vec;
sub_v2_v2v2(v_ab, v_b, v_a);
dist = len_v2(v_ab);
if (/* out of range */
(dist > rad_a + rad_b) ||
/* fully-contained in the other */
(dist < abs(rad_a - rad_b)) ||
/* co-incident */
(dist < FLT_EPSILON))
{
/* out of range */
PyTuple_SET_ITEM(ret, 0, Py_None); Py_INCREF(Py_None);
PyTuple_SET_ITEM(ret, 1, Py_None); Py_INCREF(Py_None);
}
else {
const float dist_delta = ((rad_a * rad_a) - (rad_b * rad_b) + (dist * dist)) / (2.0f * dist);
const float h = powf(fabsf((rad_a * rad_a) - (dist_delta * dist_delta)), 0.5f);
float i_cent[2];
float i1[2], i2[2];
i_cent[0] = v_a[0] + ((v_ab[0] * dist_delta) / dist);
i_cent[1] = v_a[1] + ((v_ab[1] * dist_delta) / dist);
i1[0] = i_cent[0] + h * v_ab[1] / dist;
i1[1] = i_cent[1] - h * v_ab[0] / dist;
i2[0] = i_cent[0] - h * v_ab[1] / dist;
i2[1] = i_cent[1] + h * v_ab[0] / dist;
PyTuple_SET_ITEM(ret, 0, Vector_CreatePyObject(i1, 2, Py_NEW, NULL));
PyTuple_SET_ITEM(ret, 1, Vector_CreatePyObject(i2, 2, Py_NEW, NULL));
}
return ret;
}
PyDoc_STRVAR(M_Geometry_normal_doc,
".. function:: normal(v1, v2, v3, v4=None)\n"
"\n"
@ -1376,6 +1456,7 @@ static PyMethodDef M_Geometry_methods[] = {
{"intersect_line_sphere", (PyCFunction) M_Geometry_intersect_line_sphere, METH_VARARGS, M_Geometry_intersect_line_sphere_doc},
{"intersect_line_sphere_2d", (PyCFunction) M_Geometry_intersect_line_sphere_2d, METH_VARARGS, M_Geometry_intersect_line_sphere_2d_doc},
{"distance_point_to_plane", (PyCFunction) M_Geometry_distance_point_to_plane, METH_VARARGS, M_Geometry_distance_point_to_plane_doc},
{"intersect_sphere_sphere_2d", (PyCFunction) M_Geometry_intersect_sphere_sphere_2d, METH_VARARGS, M_Geometry_intersect_sphere_sphere_2d_doc},
{"area_tri", (PyCFunction) M_Geometry_area_tri, METH_VARARGS, M_Geometry_area_tri_doc},
{"normal", (PyCFunction) M_Geometry_normal, METH_VARARGS, M_Geometry_normal_doc},
{"barycentric_transform", (PyCFunction) M_Geometry_barycentric_transform, METH_VARARGS, M_Geometry_barycentric_transform_doc},