- added a new math function double_round, useful for rounding a number to a number of decimal places.

- added Mathutils vector method, vec.asTuple(round), since this is tedious in python and fairly common task.

1 files changed, 31 insertions, 0 deletions

diff --git a/source/blender/blenlib/intern/math_base.c b/source/blender/blenlib/intern/math_base.c
index f3fe09c088f..e1a53a09d40 100644
--- a/source/blender/blenlib/intern/math_base.c
+++ b/source/blender/blenlib/intern/math_base.c
@@ -109,3 +109,34 @@ float power_of_2(float val)
 	return (float)pow(2, ceil(log(val) / log(2)));
 }
 
+/* from python 3.1 floatobject.c
+ * ndigits must be between 0 and 21 */
+double double_round(double x, int ndigits) {
+	double pow1, pow2, y, z;
+	if (ndigits >= 0) {
+		pow1 = pow(10.0, (double)ndigits);
+		pow2 = 1.0;
+		y = (x*pow1)*pow2;
+		/* if y overflows, then rounded value is exactly x */
+		if (!finite(y))
+			return x;
+	}
+	else {
+		pow1 = pow(10.0, (double)-ndigits);
+		pow2 = 1.0; /* unused; silences a gcc compiler warning */
+		y = x / pow1;
+	}
+
+	z = round(y);
+	if (fabs(y-z) == 0.5)
+		/* halfway between two integers; use round-half-even */
+		z = 2.0*round(y/2.0);
+
+	if (ndigits >= 0)
+		z = (z / pow2) / pow1;
+	else
+		z *= pow1;
+
+	/* if computation resulted in overflow, raise OverflowError */
+	return z;
+}