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Use graphene_ray_t to pick actors

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This commit introduces a few important changes in order to
acommodate graphene_ray_t. Most of them are positive changes,
so don't panic :)

The first very visible change is that neither the actor box
nor the clip rectangles are projected before being pushed.
This required changing the parameters of the related functions
at both ClutterPickContext, and ClutterPickStack, to receive
boxes instead of vertices. These rectangles are projected on
demand now, so in the best case (first actor picked) only
one projection happens; and in the worst case, it projects
as much as it does now.

The second important change is that there are no more checks
for axis-alignment anymore. That's because picking now happens
in 3D space, using triangles.

Talking about triangles in 3D space, this is what is used now
for picking. We break down each actor rectangle in 2 triangles,
and check if the projected pick point is inside any one of them,
of if the ray intersects any one of them. The same check happens
for the clip rectangles.

Checking the projected pick point is both an optimization for the
2D case, and a workaround to graphene_ray_t problems with float
precision, which is specially visible on edges such as the top
bar.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1509
This commit is contained in:
Georges Basile Stavracas Neto 2020-10-17 11:52:45 -03:00
parent 620f0ad74b
commit 7d25cbe87f
6 changed files with 155 additions and 219 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
clutter/clutter/clutter-actor.c
View File

@ -1243,57 +1243,6 @@ clutter_actor_verify_map_state (ClutterActor *self)
#endif /* CLUTTER_ENABLE_DEBUG */
static gboolean
_clutter_actor_transform_local_box_to_stage (ClutterActor *self,
ClutterStage *stage,
ClutterPickContext *pick_context,
const ClutterActorBox *box,
graphene_point_t vertices[4])
{
ClutterActor *stage_actor = CLUTTER_ACTOR (stage);
ClutterActorPrivate *stage_priv = stage_actor->priv;
graphene_matrix_t modelview, transform_to_stage;
int v;
ensure_valid_actor_transform (stage_actor);
if (!stage_priv->has_inverse_transform)
return FALSE;
clutter_pick_context_get_transform (pick_context, &modelview);
graphene_matrix_multiply (&modelview,
&stage_priv->inverse_transform,
&transform_to_stage);
vertices[0].x = box->x1;
vertices[0].y = box->y1;
vertices[1].x = box->x2;
vertices[1].y = box->y1;
vertices[2].x = box->x2;
vertices[2].y = box->y2;
vertices[3].x = box->x1;
vertices[3].y = box->y2;
for (v = 0; v < 4; v++)
{
float z = 0.f;
float w = 1.f;
cogl_graphene_matrix_project_point (&transform_to_stage,
&vertices[v].x,
&vertices[v].y,
&z,
&w);
clutter_round_to_256ths (&vertices[v].x);
clutter_round_to_256ths (&vertices[v].y);
}
return TRUE;
}
/**
* clutter_actor_pick_box:
* @self: The #ClutterActor being "pick" painted.
@ -1311,38 +1260,13 @@ clutter_actor_pick_box (ClutterActor *self,
ClutterPickContext *pick_context,
const ClutterActorBox *box)
{
ClutterStage *stage;
graphene_point_t vertices[4];
g_return_if_fail (CLUTTER_IS_ACTOR (self));
g_return_if_fail (box != NULL);
if (box->x1 >= box->x2 || box->y1 >= box->y2)
return;
stage = CLUTTER_STAGE (_clutter_actor_get_stage_internal (self));
if (_clutter_actor_transform_local_box_to_stage (self, stage, pick_context,
box, vertices))
clutter_pick_context_log_pick (pick_context, vertices, self);
}
static gboolean
_clutter_actor_push_pick_clip (ClutterActor *self,
ClutterPickContext *pick_context,
const ClutterActorBox *clip)
{
ClutterStage *stage;
graphene_point_t vertices[4];
stage = CLUTTER_STAGE (_clutter_actor_get_stage_internal (self));
if (!_clutter_actor_transform_local_box_to_stage (self, stage, pick_context,
clip, vertices))
return FALSE;
clutter_pick_context_push_clip (pick_context, vertices);
return TRUE;
clutter_pick_context_log_pick (pick_context, box, self);
}
static void
@ -4054,7 +3978,7 @@ clutter_actor_pick (ClutterActor *actor,
}
if (clip_set)
clip_set = _clutter_actor_push_pick_clip (actor, pick_context, &clip);
clutter_pick_context_push_clip (pick_context, &clip);
priv->next_effect_to_paint = NULL;
if (priv->effects)

22
clutter/clutter/clutter-pick-context.c
View File

@ -110,32 +110,32 @@ clutter_pick_context_steal_stack (ClutterPickContext *pick_context)
/**
* clutter_pick_context_log_pick:
* @pick_context: a #ClutterPickContext
* @vertices: (array fixed-size=4): array of #graphene_point_t
* @box: a #ClutterActorBox
* @actor: a #ClutterActor
*
* Logs a pick rectangle into the pick stack.
*/
void
clutter_pick_context_log_pick (ClutterPickContext *pick_context,
const graphene_point_t vertices[4],
ClutterActor *actor)
clutter_pick_context_log_pick (ClutterPickContext *pick_context,
const ClutterActorBox *box,
ClutterActor *actor)
{
clutter_pick_stack_log_pick (pick_context->pick_stack, vertices, actor);
clutter_pick_stack_log_pick (pick_context->pick_stack, box, actor);
}
/**
* clutter_pick_context_push_clip:
* @pick_context: a #ClutterPickContext
* @vertices: (array fixed-size=4): array of #graphene_point_t
* @box: a #ClutterActorBox
*
* Pushes a clip rectangle defined by @vertices into the pick stack.
* Pop with clutter_pick_context_pop_clip() when done.
* Pushes a clip rectangle defined by @box into the pick stack. Pop with
* clutter_pick_context_pop_clip() when done.
*/
void
clutter_pick_context_push_clip (ClutterPickContext *pick_context,
const graphene_point_t vertices[4])
clutter_pick_context_push_clip (ClutterPickContext *pick_context,
const ClutterActorBox *box)
{
clutter_pick_stack_push_clip (pick_context->pick_stack, vertices);
clutter_pick_stack_push_clip (pick_context->pick_stack, box);
}
/**

10
clutter/clutter/clutter-pick-context.h
View File

@ -50,13 +50,13 @@ CLUTTER_EXPORT
ClutterPickMode clutter_pick_context_get_mode (ClutterPickContext *pick_context);
CLUTTER_EXPORT
void clutter_pick_context_log_pick (ClutterPickContext *pick_context,
const graphene_point_t vertices[4],
ClutterActor *actor);
void clutter_pick_context_log_pick (ClutterPickContext *pick_context,
const ClutterActorBox *box,
ClutterActor *actor);
CLUTTER_EXPORT
void clutter_pick_context_push_clip (ClutterPickContext *pick_context,
const graphene_point_t vertices[4]);
void clutter_pick_context_push_clip (ClutterPickContext *pick_context,
const ClutterActorBox *box);
CLUTTER_EXPORT
void clutter_pick_context_pop_clip (ClutterPickContext *pick_context);

17
clutter/clutter/clutter-pick-stack-private.h
View File

@ -39,12 +39,12 @@ void clutter_pick_stack_unref (ClutterPickStack *pick_stack);
void clutter_pick_stack_seal (ClutterPickStack *pick_stack);
void clutter_pick_stack_log_pick (ClutterPickStack *pick_stack,
const graphene_point_t vertices[4],
ClutterActor *actor);
void clutter_pick_stack_log_pick (ClutterPickStack *pick_stack,
const ClutterActorBox *box,
ClutterActor *actor);
void clutter_pick_stack_push_clip (ClutterPickStack *pick_stack,
const graphene_point_t vertices[4]);
void clutter_pick_stack_push_clip (ClutterPickStack *pick_stack,
const ClutterActorBox *box);
void clutter_pick_stack_pop_clip (ClutterPickStack *pick_stack);
@ -56,9 +56,10 @@ void clutter_pick_stack_get_transform (ClutterPickStack *pick_stack,
void clutter_pick_stack_pop_transform (ClutterPickStack *pick_stack);
ClutterActor * clutter_pick_stack_find_actor_at (ClutterPickStack *pick_stack,
float x,
float y);
ClutterActor *
clutter_pick_stack_search_actor (ClutterPickStack *pick_stack,
const graphene_point3d_t *point,
const graphene_ray_t *ray);
G_END_DECLS

208
clutter/clutter/clutter-pick-stack.c
View File

@ -20,17 +20,23 @@
typedef struct
{
graphene_point_t vertices[4];
graphene_point3d_t vertices[4];
CoglMatrixEntry *matrix_entry;
ClutterActorBox rect;
gboolean projected;
} Record;
typedef struct
{
Record base;
ClutterActor *actor;
int clip_index;
CoglMatrixEntry *matrix_entry;
} PickRecord;
typedef struct
{
Record base;
int prev;
graphene_point_t vertices[4];
CoglMatrixEntry *matrix_entry;
} PickClipRecord;
struct _ClutterPickStack
@ -48,133 +54,101 @@ struct _ClutterPickStack
G_DEFINE_BOXED_TYPE (ClutterPickStack, clutter_pick_stack,
clutter_pick_stack_ref, clutter_pick_stack_unref)
static gboolean
is_quadrilateral_axis_aligned_rectangle (const graphene_point_t vertices[4])
static void
project_vertices (CoglMatrixEntry *matrix_entry,
const ClutterActorBox *box,
graphene_point3d_t vertices[4])
{
graphene_matrix_t m;
int i;
for (i = 0; i < 4; i++)
{
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;
}
cogl_matrix_entry_get (matrix_entry, &m);
static gboolean
is_inside_axis_aligned_rectangle (const graphene_point_t *point,
const graphene_point_t vertices[4])
{
float min_x = FLT_MAX;
float max_x = -FLT_MAX;
float min_y = FLT_MAX;
float max_y = -FLT_MAX;
int i;
graphene_point3d_init (&vertices[0], box->x1, box->y1, 0.f);
graphene_point3d_init (&vertices[1], box->x2, box->y1, 0.f);
graphene_point3d_init (&vertices[2], box->x2, box->y2, 0.f);
graphene_point3d_init (&vertices[3], box->x1, box->y2, 0.f);
for (i = 0; i < 4; i++)
{
min_x = MIN (min_x, vertices[i].x);
min_y = MIN (min_y, vertices[i].y);
max_x = MAX (max_x, vertices[i].x);
max_y = MAX (max_y, vertices[i].y);
float w = 1.f;
cogl_graphene_matrix_project_point (&m,
&vertices[i].x,
&vertices[i].y,
&vertices[i].z,
&w);
}
return (point->x >= min_x &&
point->y >= min_y &&
point->x < max_x &&
point->y < max_y);
}
static int
clutter_point_compare_line (const graphene_point_t *p,
const graphene_point_t *a,
const graphene_point_t *b)
static void
maybe_project_record (Record *rec)
{
graphene_vec3_t vec_pa;
graphene_vec3_t vec_pb;
graphene_vec3_t cross;
float cross_z;
graphene_vec3_init (&vec_pa, p->x - a->x, p->y - a->y, 0.f);
graphene_vec3_init (&vec_pb, p->x - b->x, p->y - b->y, 0.f);
graphene_vec3_cross (&vec_pa, &vec_pb, &cross);
cross_z = graphene_vec3_get_z (&cross);
if (cross_z > 0.f)
return 1;
else if (cross_z < 0.f)
return -1;
else
return 0;
}
static gboolean
is_inside_unaligned_rectangle (const graphene_point_t *point,
const graphene_point_t vertices[4])
{
unsigned int i;
int first_side;
first_side = 0;
for (i = 0; i < 4; i++)
if (!rec->projected)
{
int side;
side = clutter_point_compare_line (point,
&vertices[i],
&vertices[(i + 1) % 4]);
if (side)
{
if (first_side == 0)
first_side = side;
else if (side != first_side)
return FALSE;
}
project_vertices (rec->matrix_entry, &rec->rect, rec->vertices);
rec->projected = TRUE;
}
if (first_side == 0)
return FALSE;
return TRUE;
}
static gboolean
is_inside_input_region (const graphene_point_t *point,
const graphene_point_t vertices[4])
ray_intersects_input_region (Record *rec,
const graphene_ray_t *ray,
const graphene_point3d_t *point)
{
graphene_triangle_t t0, t1;
if (is_quadrilateral_axis_aligned_rectangle (vertices))
return is_inside_axis_aligned_rectangle (point, vertices);
else
return is_inside_unaligned_rectangle (point, vertices);
maybe_project_record (rec);
/*
* Degrade the projected quad into the following triangles:
*
* 0 -------------- 1
* | • |
* | • t0 |
* | • |
* | t1 • |
* | • |
* 3 -------------- 2
*/
graphene_triangle_init_from_point3d (&t0,
&rec->vertices[0],
&rec->vertices[1],
&rec->vertices[2]);
graphene_triangle_init_from_point3d (&t1,
&rec->vertices[0],
&rec->vertices[2],
&rec->vertices[3]);
if (graphene_triangle_contains_point (&t0, point) ||
graphene_triangle_contains_point (&t1, point) ||
graphene_ray_intersects_triangle (ray, &t0) ||
graphene_ray_intersects_triangle (ray, &t1))
return TRUE;
return FALSE;
}
static gboolean
pick_record_contains_point (ClutterPickStack *pick_stack,
const PickRecord *rec,
float x,
float y)
ray_intersects_record (ClutterPickStack *pick_stack,
PickRecord *rec,
const graphene_point3d_t *point,
const graphene_ray_t *ray)
{
const graphene_point_t point = GRAPHENE_POINT_INIT (x, y);
int clip_index;
if (!is_inside_input_region (&point, rec->vertices))
if (!ray_intersects_input_region (&rec->base, ray, point))
return FALSE;
clip_index = rec->clip_index;
while (clip_index >= 0)
{
const PickClipRecord *clip =
PickClipRecord *clip =
&g_array_index (pick_stack->clip_stack, PickClipRecord, clip_index);
if (!is_inside_input_region (&point, clip->vertices))
if (!ray_intersects_input_region (&clip->base, ray, point))
return FALSE;
clip_index = clip->prev;
@ -230,14 +204,14 @@ static void
clear_pick_record (gpointer data)
{
PickRecord *rec = data;
g_clear_pointer (&rec->matrix_entry, cogl_matrix_entry_unref);
g_clear_pointer (&rec->base.matrix_entry, cogl_matrix_entry_unref);
}
static void
clear_clip_record (gpointer data)
{
PickClipRecord *clip = data;
g_clear_pointer (&clip->matrix_entry, cogl_matrix_entry_unref);
g_clear_pointer (&clip->base.matrix_entry, cogl_matrix_entry_unref);
}
/**
@ -308,7 +282,7 @@ clutter_pick_stack_seal (ClutterPickStack *pick_stack)
void
clutter_pick_stack_log_pick (ClutterPickStack *pick_stack,
const graphene_point_t vertices[4],
const ClutterActorBox *box,
ClutterActor *actor)
{
PickRecord rec;
@ -317,27 +291,29 @@ clutter_pick_stack_log_pick (ClutterPickStack *pick_stack,
g_assert (!pick_stack->sealed);
memcpy (rec.vertices, vertices, 4 * sizeof (graphene_point_t));
rec.actor = actor;
rec.clip_index = pick_stack->current_clip_stack_top;
rec.matrix_entry = cogl_matrix_stack_get_entry (pick_stack->matrix_stack);
cogl_matrix_entry_ref (rec.matrix_entry);
rec.base.rect = *box;
rec.base.projected = FALSE;
rec.base.matrix_entry = cogl_matrix_stack_get_entry (pick_stack->matrix_stack);
cogl_matrix_entry_ref (rec.base.matrix_entry);
g_array_append_val (pick_stack->vertices_stack, rec);
}
void
clutter_pick_stack_push_clip (ClutterPickStack *pick_stack,
const graphene_point_t vertices[4])
clutter_pick_stack_push_clip (ClutterPickStack *pick_stack,
const ClutterActorBox *box)
{
PickClipRecord clip;
g_assert (!pick_stack->sealed);
clip.prev = pick_stack->current_clip_stack_top;
memcpy (clip.vertices, vertices, 4 * sizeof (graphene_point_t));
clip.matrix_entry = cogl_matrix_stack_get_entry (pick_stack->matrix_stack);
cogl_matrix_entry_ref (clip.matrix_entry);
clip.base.rect = *box;
clip.base.projected = FALSE;
clip.base.matrix_entry = cogl_matrix_stack_get_entry (pick_stack->matrix_stack);
cogl_matrix_entry_ref (clip.base.matrix_entry);
g_array_append_val (pick_stack->clip_stack, clip);
pick_stack->current_clip_stack_top = pick_stack->clip_stack->len - 1;
@ -386,9 +362,9 @@ clutter_pick_stack_pop_transform (ClutterPickStack *pick_stack)
}
ClutterActor *
clutter_pick_stack_find_actor_at (ClutterPickStack *pick_stack,
float x,
float y)
clutter_pick_stack_search_actor (ClutterPickStack *pick_stack,
const graphene_point3d_t *point,
const graphene_ray_t *ray)
{
int i;
@ -398,10 +374,10 @@ clutter_pick_stack_find_actor_at (ClutterPickStack *pick_stack,
*/
for (i = pick_stack->vertices_stack->len - 1; i >= 0; i--)
{
const PickRecord *rec =
PickRecord *rec =
&g_array_index (pick_stack->vertices_stack, PickRecord, i);
if (rec->actor && pick_record_contains_point (pick_stack, rec, x, y))
if (rec->actor && ray_intersects_record (pick_stack, rec, point, ray))
return rec->actor;
}

37
clutter/clutter/clutter-stage.c
View File

@ -1130,6 +1130,37 @@ _clutter_stage_has_full_redraw_queued (ClutterStage *stage)
return is_full_stage_redraw_queued (stage);
}
static void
setup_ray_for_coordinates (ClutterStage *stage,
float x,
float y,
graphene_point3d_t *point,
graphene_ray_t *ray)
{
ClutterStagePrivate *priv = stage->priv;
graphene_point3d_t camera_position;
graphene_point3d_t p;
graphene_vec3_t direction;
graphene_vec3_t cv;
graphene_vec3_t v;
camera_position = GRAPHENE_POINT3D_INIT_ZERO;
graphene_vec3_init (&cv,
camera_position.x,
camera_position.y,
camera_position.z);
p = GRAPHENE_POINT3D_INIT (x, y, 0.f);
graphene_matrix_transform_point3d (&priv->view, &p, &p);
graphene_vec3_init (&v, p.x, p.y, p.z);
graphene_vec3_subtract (&v, &cv, &direction);
graphene_vec3_normalize (&direction, &direction);
graphene_ray_init (ray, &camera_position, &direction);
graphene_point3d_init_from_point (point, &p);
}
static ClutterActor *
_clutter_stage_do_pick_on_view (ClutterStage *stage,
float x,
@ -1138,6 +1169,8 @@ _clutter_stage_do_pick_on_view (ClutterStage *stage,
ClutterStageView *view)
{
ClutterStagePrivate *priv = stage->priv;
graphene_point3d_t p;
graphene_ray_t ray;
ClutterActor *actor;
COGL_TRACE_BEGIN_SCOPED (ClutterStagePickView, "Pick (view)");
@ -1157,7 +1190,9 @@ _clutter_stage_do_pick_on_view (ClutterStage *stage,
clutter_pick_context_destroy (pick_context);
}
actor = clutter_pick_stack_find_actor_at (priv->pick_stack, x, y);
setup_ray_for_coordinates (stage, x, y, &p, &ray);
actor = clutter_pick_stack_search_actor (priv->pick_stack, &p, &ray);
return actor ? actor : CLUTTER_ACTOR (stage);
}