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implemented smoothstep alpha function

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This commit is contained in:
Tomas Frydrych 2007-05-16 11:32:50 +00:00
parent ee928107cb
commit 9dfe31a542
6 changed files with 206 additions and 17 deletions
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10
ChangeLog
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@ -1,3 +1,13 @@
2007-05-16 Tomas Frydrych <tf@openedhand.com>
* clutter/clutter-alpha.h:
* clutter/clutter-alpha.c:
* doc/reference/clutter-sections.txt:
* doc/rererence/clutter.types:
* doc/reference/tmpl/clutter-alpha.sgml:
clutter_smoothstep_func alpha function,
ClutterSmoothstep struct for smoothstep function data.
2007-05-16 Matthew Allum <mallum@openedhand.com>
* clutter/clutter-backend.c:

127
clutter/clutter-alpha.c
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@ -6,8 +6,9 @@
* Authored By Matthew Allum <mallum@openedhand.com>
* Jorn Baayen <jorn@openedhand.com>
* Emmanuele Bassi <ebassi@openedhand.com>
* Tomas Frydrych <tf@openedhand.com>
*
* Copyright (C) 2006 OpenedHand
* Copyright (C) 2006, 2007 OpenedHand
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@ -647,3 +648,127 @@ clutter_square_func (ClutterAlpha *alpha,
return (current_frame_num > (n_frames / 2)) ? CLUTTER_ALPHA_MAX_ALPHA
: 0;
}
/**
* clutter_smoothstep_copy:
* @smoothstep: a #ClutterSmoothstep
*
* Makes an allocated copy of a smoothstep.
*
* Return value: the copied smoothstep.
*
* Since: 0.4
*/
ClutterSmoothstep *
clutter_smoothstep_copy (const ClutterSmoothstep *smoothstep)
{
ClutterSmoothstep *copy;
copy = g_slice_new0 (ClutterSmoothstep);
*copy = *smoothstep;
return copy;
}
/**
* clutter_smoothstep_free:
* @smoothstep: a #ClutterSmoothstep
*
* Frees the memory of an allocated smoothstep.
*
* Since: 0.4
*/
void
clutter_smoothstep_free (ClutterSmoothstep *smoothstep)
{
if (G_LIKELY (smoothstep))
{
g_slice_free (ClutterSmoothstep, smoothstep);
}
}
GType
clutter_smoothstep_get_type (void)
{
static GType our_type = 0;
if (G_UNLIKELY (!our_type))
{
our_type =
g_boxed_type_register_static ("ClutterSmoothstep",
(GBoxedCopyFunc) clutter_smoothstep_copy,
(GBoxedFreeFunc) clutter_smoothstep_free);
}
return our_type;
}
/**
* clutter_smoothstep_func:
* @alpha: a #ClutterAlpha
* @data: pointer to a #ClutterSmoothstep defining the minimum and
* maximum thresholds for the smoothstep as supplied to
* clutter_alpha_set_func().
*
* Convenience alpha function for a smoothstep curve. You can use this
* function as the alpha function for clutter_alpha_set_func().
*
* Return value: an alpha value
*
* Since: 0.4
*/
guint32
clutter_smoothstep_func (ClutterAlpha * alpha,
gpointer * data)
{
ClutterSmoothstep * smoothstep = data;
ClutterTimeline * timeline;
gint frame;
gint n_frames;
gint32 r;
gint32 x;
/*
* The smoothstep function uses f(x) = -2x^3 + 3x^2 where x is from <0,1>,
* and precission is critical -- we use 8.24 fixed format for this operation.
* The earlier operations involve division, which we cannot do in 8.24 for
* numbers in <0,1> we use ClutterFixed.
*/
g_return_val_if_fail (data, 0);
timeline = clutter_alpha_get_timeline (alpha);
frame = clutter_timeline_get_current_frame (timeline);
n_frames = clutter_timeline_get_n_frames (timeline);
r = CFX_DIV (frame, n_frames);
if (r <= smoothstep->min)
return 0;
if (r >= smoothstep->max)
return CLUTTER_ALPHA_MAX_ALPHA;
/*
* Normalize x for the smoothstep polynomal.
*
* Convert result to 8.24 for next step.
*/
x = CFX_DIV ((r - smoothstep->min), (smoothstep->max - smoothstep->min))
<< 8;
/*
* f(x) = -2x^3 + 3x^2
*
* Convert result to ClutterFixed to avoid overflow in next step.
*/
r = ((x >> 12) * (x >> 12) * 3 - (x >> 15) * (x >> 16) * (x >> 16)) >> 8;
g_debug ("Frame %d of %d, x %f, ret %f",
frame, n_frames,
CLUTTER_FIXED_TO_DOUBLE (x >> 8),
CLUTTER_FIXED_TO_DOUBLE (r));
return CFX_INT (r * CLUTTER_ALPHA_MAX_ALPHA);
}

21
clutter/clutter-alpha.h
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@ -6,8 +6,9 @@
* Authored By Matthew Allum <mallum@openedhand.com>
* Jorn Baayen <jorn@openedhand.com>
* Emmanuele Bassi <ebassi@openedhand.com>
* Tomas Frydrych <tf@openedhand.com>
*
* Copyright (C) 2006 OpenedHand
* Copyright (C) 2006, 2007 OpenedHand
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
@ -30,6 +31,7 @@
#include <glib-object.h>
#include <clutter/clutter-timeline.h>
#include <clutter/clutter-fixed.h>
G_BEGIN_DECLS
@ -106,6 +108,21 @@ ClutterTimeline *clutter_alpha_get_timeline (ClutterAlpha *alpha);
#define CLUTTER_ALPHA_SINE clutter_sine_func
/* FIXME add SINE_INC/DEC */
#define CLUTTER_ALPHA_SQUARE clutter_square_func
#define CLUTTER_ALPHA_SMOOTHSTEP clutter_smoothstep_func
#define CLUTTER_TYPE_SMOOTHSTEP (clutter_smoothstep_get_type ())
typedef struct _ClutterSmoothstep ClutterSmoothstep;
struct _ClutterSmoothstep
{
ClutterFixed min;
ClutterFixed max;
};
ClutterSmoothstep * clutter_smoothstep_copy (const ClutterSmoothstep *smoothstep);
void clutter_smoothstep_free (ClutterSmoothstep *smoothstep);
guint32 clutter_ramp_inc_func (ClutterAlpha *alpha,
gpointer dummy);
@ -117,6 +134,8 @@ guint32 clutter_sine_func (ClutterAlpha *alpha,
gpointer dummy);
guint32 clutter_square_func (ClutterAlpha *alpha,
gpointer dummy);
guint32 clutter_smoothstep_func (ClutterAlpha *alpha,
gpointer *data);
G_END_DECLS

5
doc/reference/clutter-sections.txt
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@ -101,6 +101,9 @@ ClutterAlphaFunc
clutter_alpha_set_func
clutter_alpha_set_timeline
clutter_alpha_get_timeline
ClutterSmoothstep
clutter_smoothstep_copy
clutter_smoothstep_free
CLUTTER_ALPHA_RAMP_INC
clutter_ramp_inc_func
CLUTTER_ALPHA_RAMP_DEC
@ -111,6 +114,8 @@ CLUTTER_ALPHA_SINE
clutter_sine_func
CLUTTER_ALPHA_SQUARE
clutter_square_func
CLUTTER_ALPHA_SMOOTHSTEP
clutter_smoothstep_func
<SUBSECTION Standard>
CLUTTER_ALPHA
CLUTTER_IS_ALPHA

1
doc/reference/clutter.types
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@ -11,6 +11,7 @@ clutter_timeline_get_type
clutter_media_get_type
clutter_behaviour_get_type
clutter_alpha_get_type
clutter_smoothstep_get_type
clutter_behaviour_bspline_get_type
clutter_behaviour_ellipse_get_type
clutter_behaviour_opacity_get_type

29
doc/reference/tmpl/clutter-alpha.sgml
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@ -123,6 +123,35 @@ transforming the current position in the timeline.
@Returns:
<!-- ##### STRUCT ClutterSmoothstep ##### -->
<para>
Represents minimum and maximum thresholds for the smoothstep function. The
thresholds are values from &lt;0,1&gt; relative to the frame-length of the behaviour,
i.e., if the behaviour consists of 60 frames, threshold of 0.25 corresponds to
frame 15, and threshold of 1.0 to frame 60.
</para>
@min: lower threshold; a #ClutterFixed value from &lt;0,1&gt;
@max: upper threshold; a #ClutterFixed value from &lt;0,1&gt;
<!-- ##### FUNCTION clutter_smoothstep_copy ##### -->
<para>
</para>
@smoothstep:
@Returns:
<!-- ##### FUNCTION clutter_smoothstep_free ##### -->
<para>
</para>
@smoothstep:
<!-- ##### MACRO CLUTTER_ALPHA_RAMP_INC ##### -->
<para>
Symbolic name for passing clutter_ramp_inc_func().