[829] | 1 | // Python - C extension for finite_volumes util module. |
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| 2 | // |
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| 3 | // To compile (Python2.3): |
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| 4 | // gcc -c util_ext.c -I/usr/include/python2.3 -o util_ext.o -Wall -O |
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| 5 | // gcc -shared util_ext.o -o util_ext.so |
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| 6 | // |
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| 7 | // See the module util.py |
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| 8 | // |
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| 9 | // |
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| 10 | // Ole Nielsen, GA 2004 |
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| 11 | |
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| 12 | #include "Python.h" |
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| 13 | #include "Numeric/arrayobject.h" |
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| 14 | #include "math.h" |
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| 15 | |
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| 16 | //Shared snippets |
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| 17 | #include "util_ext.h" |
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| 18 | |
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| 19 | |
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| 20 | |
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| 21 | int _point_on_line(double x, double y, |
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| 22 | double x0, double y0, |
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| 23 | double x1, double y1) { |
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| 24 | /*Determine whether a point is on a line segment |
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| 25 | |
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| 26 | Input: x, y, x0, x0, x1, y1: where |
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| 27 | point is given by x, y |
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| 28 | line is given by (x0, y0) and (x1, y1) |
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| 29 | |
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| 30 | */ |
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| 31 | |
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| 32 | double a0, a1, a_normal0, a_normal1, b0, b1, len_a, len_b; |
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| 33 | |
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| 34 | a0 = x - x0; |
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| 35 | a1 = y - y0; |
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| 36 | |
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| 37 | a_normal0 = a1; |
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| 38 | a_normal1 = -a0; |
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| 39 | |
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| 40 | b0 = x1 - x0; |
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| 41 | b1 = y1 - y0; |
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| 42 | |
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| 43 | if ( a_normal0*b0 + a_normal1*b1 == 0 ) { |
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| 44 | //Point is somewhere on the infinite extension of the line |
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| 45 | |
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| 46 | len_a = sqrt(a0*a0 + a1*a1); |
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| 47 | len_b = sqrt(b0*b0 + b1*b1); |
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| 48 | |
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| 49 | if (a0*b0 + a1*b1 >= 0 && len_a <= len_b) { |
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| 50 | return 1; |
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| 51 | } else { |
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| 52 | return 0; |
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| 53 | } |
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| 54 | } else { |
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| 55 | return 0; |
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| 56 | } |
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| 57 | } |
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| 58 | |
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| 59 | |
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| 60 | |
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| 61 | // Gateways to Python |
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| 62 | PyObject *point_on_line(PyObject *self, PyObject *args) { |
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| 63 | // |
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| 64 | // point_on_line(x, y, x0, y0, x1, y1) |
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| 65 | // |
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| 66 | |
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| 67 | double x, y, x0, y0, x1, y1; |
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| 68 | int res; |
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| 69 | PyObject *result; |
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| 70 | |
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| 71 | // Convert Python arguments to C |
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| 72 | if (!PyArg_ParseTuple(args, "dddddd", &x, &y, &x0, &y0, &x1, &y1)) |
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| 73 | return NULL; |
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| 74 | |
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| 75 | |
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| 76 | // Call underlying routine |
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| 77 | res = _point_on_line(x, y, x0, y0, x1, y1); |
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| 78 | |
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| 79 | // Return values a and b |
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| 80 | result = Py_BuildValue("i", res); |
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| 81 | return result; |
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| 82 | } |
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| 83 | |
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| 84 | |
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| 85 | PyObject *gradient(PyObject *self, PyObject *args) { |
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| 86 | // |
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| 87 | // a,b = gradient(x0, y0, x1, y1, x2, y2, q0, q1, q2) |
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| 88 | // |
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| 89 | |
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| 90 | double x0, y0, x1, y1, x2, y2, q0, q1, q2, a, b; |
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| 91 | PyObject *result; |
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| 92 | |
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| 93 | // Convert Python arguments to C |
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| 94 | if (!PyArg_ParseTuple(args, "ddddddddd", &x0, &y0, &x1, &y1, &x2, &y2, |
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| 95 | &q0, &q1, &q2)) |
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| 96 | return NULL; |
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| 97 | |
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| 98 | |
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| 99 | // Call underlying routine |
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| 100 | _gradient(x0, y0, x1, y1, x2, y2, |
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| 101 | q0, q1, q2, &a, &b); |
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| 102 | |
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| 103 | // Return values a and b |
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| 104 | result = Py_BuildValue("dd", a, b); |
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| 105 | return result; |
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| 106 | } |
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| 107 | |
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| 108 | |
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| 109 | // Method table for python module |
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| 110 | static struct PyMethodDef MethodTable[] = { |
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| 111 | /* The cast of the function is necessary since PyCFunction values |
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| 112 | * only take two PyObject* parameters, and rotate() takes |
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| 113 | * three. |
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| 114 | */ |
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| 115 | |
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| 116 | //{"rotate", (PyCFunction)rotate, METH_VARARGS | METH_KEYWORDS, "Print out"}, |
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| 117 | {"gradient", gradient, METH_VARARGS, "Print out"}, |
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| 118 | {"point_on_line", point_on_line, METH_VARARGS, "Print out"}, |
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| 119 | {NULL, NULL, 0, NULL} /* sentinel */ |
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| 120 | }; |
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| 121 | |
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| 122 | |
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| 123 | |
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| 124 | // Module initialisation |
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| 125 | void initutil_ext(void){ |
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| 126 | Py_InitModule("util_ext", MethodTable); |
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| 127 | |
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| 128 | import_array(); //Necessary for handling of NumPY structures |
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| 129 | } |
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| 130 | |
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