Hi,
This is patch for todo item: Add overlaps geometric operators that
ignore point overlaps
Issue:
SELECT circle '((0,0), 1)' && circle '((2,0),1) returns True
Expectation: In above case, both figures touch other but do not overlap
(i.e. touching != overlap). Hence, it should return false.
Cause:
Less than or equal check between distance of center and sum of radius
Datum
circle_overlap(PG_FUNCTION_ARGS)
{
CIRCLE *circle1 = PG_GETARG_CIRCLE_P(0);
CIRCLE *circle2 = PG_GETARG_CIRCLE_P(1);
PG_RETURN_BOOL(FPle(point_dt(&circle1->center, &circle2->center),
float8_pl(circle1->radius, circle2->radius)));
}
Possible fix:
# Don't check for <= , just < would suffice.
Datum
circle_overlap(PG_FUNCTION_ARGS)
{
CIRCLE *circle1 = PG_GETARG_CIRCLE_P(0);
CIRCLE *circle2 = PG_GETARG_CIRCLE_P(1);
PG_RETURN_BOOL(FPlt(point_dt(&circle1->center, &circle2->center),
float8_pl(circle1->radius, circle2->radius)));
}
same for boxes as well.
Results:
Before:
select box '((0,0),(1,1))' && box '((0,1), (1,2))';
?column?
----------
t
(1 row)
With patch:
select box '((0,1),(1,1))' && box '((1,1), (1,2))';
?column?
----------
f
(1 row)
Bring box slightly ( > EPSILON) inside the other box
select box '((0,0),(1,1.0001))' && box '((0,1), (1,2))';
?column?
----------
t
(1 row)
similar for circle.
Now, as per as discussion
(https://www.postgresql.org/message-id/20100322175532.GG26428%40fetter.org)
and corresponding change in docs,
https://www.postgresql.org/docs/15/functions-geometry.html, it mentions
`Do these objects overlap? (One point in common makes this true.) `.
Does this means current behavior is correct? Or do we still need the
proposed change (if so, with proper updates in docs)?
If current behavior is correct, this todo item might need some update
(unless I missed anything) otherwise any suggestion is welcomed.
Also, I did some search around this and there is general sense of
differentiation between overlap and touch of geometric figures. I am not
able to find any function which can determine if two geometric figures
touch each
other at a point (and if there is real use case of this).
In any case, patch attached for a reference. Any feedback is welcomed.
--
Regards,
Ankit Kumar Pandey
From 1c180b50493c416d063bca9ed0a1669c2b1b191d Mon Sep 17 00:00:00 2001
From: Ankit Kumar Pandey <itsanki...@gmail.com>
Date: Sun, 1 Jan 2023 00:25:06 +0530
Subject: [PATCH] Ignore point overlap operation
Geometric figure does not overlap if they just
touch each other. This patch removes requirement of point overlap for
overlap condition.
---
doc/src/sgml/func.sgml | 2 +-
src/backend/utils/adt/geo_ops.c | 10 +++++-----
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 3bf8d021c3..d1abd545a4 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -11209,7 +11209,7 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple
<returnvalue>boolean</returnvalue>
</para>
<para>
- Do these objects overlap? (One point in common makes this true.)
+ Do these objects overlap? (One point in common does not count as overlap.)
Available for <type>box</type>, <type>polygon</type>,
<type>circle</type>.
</para>
diff --git a/src/backend/utils/adt/geo_ops.c b/src/backend/utils/adt/geo_ops.c
index 86da025906..6a06abfd2c 100644
--- a/src/backend/utils/adt/geo_ops.c
+++ b/src/backend/utils/adt/geo_ops.c
@@ -570,10 +570,10 @@ box_overlap(PG_FUNCTION_ARGS)
static bool
box_ov(BOX *box1, BOX *box2)
{
- return (FPle(box1->low.x, box2->high.x) &&
- FPle(box2->low.x, box1->high.x) &&
- FPle(box1->low.y, box2->high.y) &&
- FPle(box2->low.y, box1->high.y));
+ return (FPlt(box1->low.x, box2->high.x) &&
+ FPlt(box2->low.x, box1->high.x) &&
+ FPlt(box1->low.y, box2->high.y) &&
+ FPlt(box2->low.y, box1->high.y));
}
/* box_left - is box1 strictly left of box2?
@@ -4765,7 +4765,7 @@ circle_overlap(PG_FUNCTION_ARGS)
CIRCLE *circle1 = PG_GETARG_CIRCLE_P(0);
CIRCLE *circle2 = PG_GETARG_CIRCLE_P(1);
- PG_RETURN_BOOL(FPle(point_dt(&circle1->center, &circle2->center),
+ PG_RETURN_BOOL(FPlt(point_dt(&circle1->center, &circle2->center),
float8_pl(circle1->radius, circle2->radius)));
}
--
2.37.2
