[clutter] actor: Fix transforming stage point when scale is less than 1
- From: Jonas Ådahl <jadahl src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [clutter] actor: Fix transforming stage point when scale is less than 1
- Date: Fri, 11 Sep 2015 02:37:34 +0000 (UTC)
commit 5d83260b19c06f216cfdb21a57f256ebee1affef
Author: Jonas Ådahl <jadahl gmail com>
Date: Thu Sep 10 16:12:51 2015 +0800
actor: Fix transforming stage point when scale is less than 1
The commit 6cd24faaa54de3246ca45d1c7426d8b7a74f71db (actor: Clean up
transform_stage_point()) changed the validation of the transformation
matrix to ignore the fraction part of the determinant. This caused
clutter_actor_transform_stage_point() to fail and return FALSE for
actors which scale was less than 1.
Previously the validation was ('det' being a float):
det = (RQ[0][0] * ST[0][0])
+ (RQ[0][1] * ST[0][1])
+ (RQ[0][2] * ST[0][2]);
if (!det)
return FALSE;
Semantically, the if statement expression '!det' is equivalent to
'det == 0', i.e. 'det == 0.0f'. Post cleanup patches, 'det' was turned
into a double, and the if statement was changed to:
if (CLUTTER_NEARBYINT (det) == 0)
return FALSE;
which, different from before, rounds the determinant to the nearest
integer value, meaning determinant in the range (-0.5, 0.5) would be
considered invalid.
This patch reverts this part to the old behavior, while, because of the
inexact nature of floating point arithmetics, allowing a bit more liberal
meaning of "equals to 0" than '== 0.0'.
https://bugzilla.gnome.org/show_bug.cgi?id=754766
clutter/clutter-actor.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/clutter/clutter-actor.c b/clutter/clutter-actor.c
index 1cbbd5c..ad106c4 100644
--- a/clutter/clutter-actor.c
+++ b/clutter/clutter-actor.c
@@ -15190,8 +15190,8 @@ clutter_actor_transform_stage_point (ClutterActor *self,
dy2 = v[2].y - v[3].y;
det = DET (dx1, dx2, dy1, dy2);
- if (CLUTTER_NEARBYINT (det) == 0)
- return FALSE;
+ if (fabs (det) <= DBL_EPSILON)
+ return FALSE;
RQ[0][2] = DET (px, dx2, py, dy2) / det;
RQ[1][2] = DET (dx1, px, dy1, py) / det;
@@ -15236,7 +15236,7 @@ clutter_actor_transform_stage_point (ClutterActor *self,
det = (RQ[0][0] * ST[0][0])
+ (RQ[0][1] * ST[0][1])
+ (RQ[0][2] * ST[0][2]);
- if (CLUTTER_NEARBYINT (det) == 0)
+ if (fabs (det) <= DBL_EPSILON)
return FALSE;
/*
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