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Adding a readonly length_squared property to mathutils.Vector. This is simply vector.dot(vector), so nothing new is really added, but it's nice for writing more intent revealing code. In other words:

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if vec.dot(vec) > some_distance*some_distance:
    do_something()

might not be quite as obvious looking as:

if vec.length_squared > some_distance*some_distance:
    do_something()

As to why you'd want to use length_squared over length is that length uses a square root, which isn't always necessary for simple distance checks (e.g., closest object, checks like the ones above, ect).
This commit is contained in:
Mitchell Stokes
2011-08-11 09:40:14 +00:00
parent 99caa9470e
commit 165e6dbc07
1 changed files with 16 additions and 0 deletions
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16
source/blender/python/mathutils/mathutils_Vector.c
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@@ -1728,6 +1728,21 @@ static int Vector_setLength(VectorObject *self, PyObject *value)
return 0;
}
/* vector.length_squared */
static PyObject *Vector_getLengthSquared(VectorObject *self, void *UNUSED(closure))
{
double dot = 0.0f;
int i;
if(BaseMath_ReadCallback(self) == -1)
return NULL;
for(i = 0; i < self->size; i++){
dot += (double)(self->vec[i] * self->vec[i]);
}
return PyFloat_FromDouble(dot);
}
/* Get a new Vector according to the provided swizzle. This function has little
error checking, as we are in control of the inputs: the closure is set by us
in Vector_createSwizzleGetSeter. */
@@ -1851,6 +1866,7 @@ static PyGetSetDef Vector_getseters[] = {
{(char *)"z", (getter)Vector_getAxis, (setter)Vector_setAxis, (char *)"Vector Z axis (3D Vectors only).\n\n:type: float", (void *)2},
{(char *)"w", (getter)Vector_getAxis, (setter)Vector_setAxis, (char *)"Vector W axis (4D Vectors only).\n\n:type: float", (void *)3},
{(char *)"length", (getter)Vector_getLength, (setter)Vector_setLength, (char *)"Vector Length.\n\n:type: float", NULL},
{(char *)"length_squared", (getter)Vector_getLengthSquared, (setter)NULL, (char *)"Vector length squared (v.dot(v)).\n\n:type: float", NULL},
{(char *)"magnitude", (getter)Vector_getLength, (setter)Vector_setLength, (char *)"Vector Length.\n\n:type: float", NULL},
{(char *)"is_wrapped", (getter)BaseMathObject_getWrapped, (setter)NULL, (char *)BaseMathObject_Wrapped_doc, NULL},
{(char *)"owner", (getter)BaseMathObject_getOwner, (setter)NULL, (char *)BaseMathObject_Owner_doc, NULL},