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clutter/pick-stack: Use graphene_box_t for axis-aligned rectangles

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The most common case for Clutter is 2D axis-aligned actors, which
maintain these properties even after projecting to eye coordinates.
In those cases, we can use a simpler hit test by checking against
boxes.

Not only this is simpler, but this maintains an important aspect
of picking that is a requirement for Clutter: watertightness. Even
though the triangles checks do work on x86_64, they do not guarantee
watertightness. This breaks tests on ARM.

Use graphene_box_t to hit-test axis-aligned 2D actors.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1599>
This commit is contained in:
Georges Basile Stavracas Neto 2020-11-23 11:52:34 -03:00
parent aa186193b5
commit d2feaa8d67
1 changed files with 33 additions and 0 deletions
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33
clutter/clutter/clutter-pick-stack.c
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@ -91,6 +91,30 @@ maybe_project_record (Record *rec)
}
}
static inline gboolean
is_axis_aligned_2d_rectangle (const graphene_point3d_t vertices[4])
{
int i;
for (i = 0; i < 4; i++)
{
if (!G_APPROX_VALUE (vertices[i].z,
vertices[(i + 1) % 4].z,
FLT_EPSILON))
return FALSE;
if (!G_APPROX_VALUE (vertices[i].x,
vertices[(i + 1) % 4].x,
FLT_EPSILON) &&
!G_APPROX_VALUE (vertices[i].y,
vertices[(i + 1) % 4].y,
FLT_EPSILON))
return FALSE;
}
return TRUE;
}
static gboolean
ray_intersects_input_region (Record *rec,
const graphene_ray_t *ray,
@ -100,6 +124,15 @@ ray_intersects_input_region (Record *rec,
maybe_project_record (rec);
if (G_LIKELY (is_axis_aligned_2d_rectangle (rec->vertices)))
{
graphene_box_t box;
graphene_box_init_from_points (&box, 4, rec->vertices);
return graphene_box_contains_point (&box, point) ||
graphene_ray_intersects_box (ray, &box);
}
/*
* Degrade the projected quad into the following triangles:
*