mutter/doc/cookbook/examples/cb-page-fold-effect.c
Elliot Smith 74de3cfdf3 docs: Add effects chapter, with introduction and first recipe
Add an effects chapter which gives a broad overview of
the abstract classes in the effects API, plus a short
example of how to apply one of the stock Clutter
effects (ClutterColorizeEffect).

The recipe explains how to create a custom ClutterDeformEffect
to produce a page fold (code based on ClutterPageTurnEffect).

The example code includes the effect class plus a small
application to apply it to a texture.
2011-02-21 16:44:09 +00:00

251 lines
6.9 KiB
C

#include <math.h>
#include "cb-page-fold-effect.h"
G_DEFINE_TYPE (CbPageFoldEffect, cb_page_fold_effect, CLUTTER_TYPE_DEFORM_EFFECT);
#define CB_PAGE_FOLD_EFFECT_GET_PRIVATE(obj) (G_TYPE_INSTANCE_GET_PRIVATE ((obj), \
CB_TYPE_PAGE_FOLD_EFFECT, \
CbPageFoldEffectPrivate))
struct _CbPageFoldEffectPrivate
{
gdouble angle;
gdouble period;
};
enum {
PROP_0,
PROP_PERIOD,
PROP_ANGLE,
PROP_LAST
};
static GParamSpec *obj_props[PROP_LAST];
/* ClutterDeformEffect implementation */
static void
cb_page_fold_effect_deform_vertex (ClutterDeformEffect *effect,
gfloat width,
gfloat height,
CoglTextureVertex *vertex)
{
CbPageFoldEffectPrivate *priv = CB_PAGE_FOLD_EFFECT (effect)->priv;
gfloat radians = (priv->angle * priv->period) / (180.0f / G_PI);
/* rotate from the center of the actor on the y axis */
gfloat adjusted_x = vertex->x - (width / 2);
/* only rotate vertices to the right of the middle of the actor */
if (adjusted_x >= 0.0)
{
vertex->x = (vertex->z * sin (radians))
+ (adjusted_x * cos (radians))
+ width / 2;
/* NB add 1 to z to prevent "z fighting"; otherwise, when fully-folded
* the image has "stripes" where vertices from the folded part
* of the actor interfere with vertices from the unfolded part
*/
vertex->z = (vertex->z * cos (radians))
+ (adjusted_x * sin (radians))
+ 1;
}
/* adjust depth of all vertices so they fit inside the actor while folding;
* this has the effect of making the image smaller within the texture,
* but does produce a cleaner fold animation
*/
vertex->z -= width / 2;
}
/* GObject implementation */
static void
cb_page_fold_effect_set_property (GObject *gobject,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
CbPageFoldEffect *effect = CB_PAGE_FOLD_EFFECT (gobject);
switch (prop_id)
{
case PROP_PERIOD:
cb_page_fold_effect_set_period (effect, g_value_get_double (value));
break;
case PROP_ANGLE:
cb_page_fold_effect_set_angle (effect, g_value_get_double (value));
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
break;
}
}
static void
cb_page_fold_effect_get_property (GObject *gobject,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
CbPageFoldEffectPrivate *priv = CB_PAGE_FOLD_EFFECT (gobject)->priv;
switch (prop_id)
{
case PROP_PERIOD:
g_value_set_double (value, priv->period);
break;
case PROP_ANGLE:
g_value_set_double (value, priv->angle);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
break;
}
}
/* GObject class and instance init */
static void
cb_page_fold_effect_class_init (CbPageFoldEffectClass *klass)
{
GParamSpec *pspec;
ClutterDeformEffectClass *effect_class = CLUTTER_DEFORM_EFFECT_CLASS (klass);
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
effect_class->deform_vertex = cb_page_fold_effect_deform_vertex;
gobject_class->set_property = cb_page_fold_effect_set_property;
gobject_class->get_property = cb_page_fold_effect_get_property;
g_type_class_add_private (klass, sizeof (CbPageFoldEffectPrivate));
/**
* CbPageFoldEffect:period:
*
* The period of the page fold, between 0.0 (no fold) and
* 1.0 (fully folded)
*/
pspec = g_param_spec_double ("period",
"Period",
"The period of the page fold",
0.0, 1.0,
0.0,
G_PARAM_READWRITE);
obj_props[PROP_PERIOD] = pspec;
g_object_class_install_property (gobject_class, PROP_PERIOD, pspec);
/**
* CbPageFoldEffect:angle:
*
* The angle of the page fold, in degrees, between 0.0 and 180.0
*/
pspec = g_param_spec_double ("angle",
"Angle",
"The angle of the page fold, in degrees",
0.0, 180.0,
0.0,
G_PARAM_READWRITE);
obj_props[PROP_ANGLE] = pspec;
g_object_class_install_property (gobject_class, PROP_ANGLE, pspec);
}
static void
cb_page_fold_effect_init (CbPageFoldEffect *self)
{
CbPageFoldEffectPrivate *priv;
priv = self->priv = CB_PAGE_FOLD_EFFECT_GET_PRIVATE (self);
priv->period = 0.0;
priv->angle = 0.0;
}
/* public API */
ClutterEffect *
cb_page_fold_effect_new (gdouble angle,
gdouble period)
{
return g_object_new (CB_TYPE_PAGE_FOLD_EFFECT,
"angle", angle,
"period", period,
NULL);
}
/**
* cb_page_fold_effect_set_period:
* @effect: a #CbPageFoldEffect
* @period: the period of the page fold, between 0.0 and 1.0
*
* Sets the period of the page fold, between 0.0 (no fold)
* and 1.0 (fully folded)
*/
void
cb_page_fold_effect_set_period (CbPageFoldEffect *effect,
gdouble period)
{
g_return_if_fail (CB_IS_PAGE_FOLD_EFFECT (effect));
g_return_if_fail (period >= 0.0 && period <= 1.0);
effect->priv->period = period;
clutter_deform_effect_invalidate (CLUTTER_DEFORM_EFFECT (effect));
}
/**
* cb_page_fold_effect_get_period:
* @effect: a #CbPageFoldEffect
*
* Retrieves the value set using cb_page_fold_effect_get_period()
*
* Return value: the period of the page fold
*/
gdouble
cb_page_fold_effect_get_period (CbPageFoldEffect *effect)
{
g_return_val_if_fail (CB_IS_PAGE_FOLD_EFFECT (effect), 0.0);
return effect->priv->period;
}
/**
* cb_page_fold_effect_set_angle:
* @effect: #CbPageFoldEffect
* @angle: the angle of the page fold, in degrees
*
* Sets the angle of the page fold, in degrees; must be a value between
* 0.0 and 180.0
*/
void
cb_page_fold_effect_set_angle (CbPageFoldEffect *effect,
gdouble angle)
{
g_return_if_fail (CB_IS_PAGE_FOLD_EFFECT (effect));
g_return_if_fail (angle >= 0.0 && angle <= 180.0);
effect->priv->angle = angle;
clutter_deform_effect_invalidate (CLUTTER_DEFORM_EFFECT (effect));
}
/**
* cb_page_fold_effect_get_angle:
* @effect: a #CbPageFoldEffect:
*
* Retrieves the angle of the page fold, in degrees
*
* Return value: the angle of the page fold
*/
gdouble
cb_page_fold_effect_get_angle (CbPageFoldEffect *effect)
{
g_return_val_if_fail (CB_IS_PAGE_FOLD_EFFECT (effect), 0.0);
return effect->priv->angle;
}