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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.
770 lines
29 KiB
XML
770 lines
29 KiB
XML
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<chapter id="effects" xmlns:xi="http://www.w3.org/2003/XInclude">
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<title>Effects</title>
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<epigraph>
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<attribution>Roger Zelazny, from <citetitle>Prince of Chaos</citetitle>
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</attribution>
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<para>Don't wake me for the end of the world unless it has very
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good special effects</para>
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</epigraph>
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<section id="effects-introduction">
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<title>Introduction</title>
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<para>Effects modify an actor's appearance, such
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as how it is positioned, colored and textured.</para>
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<para>The Clutter API for effects contains several
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abstract classes you can subclass to create your own effects.
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It also contains several built-in effects you can use to
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modify the visual appearance of actors in a variety of ways.</para>
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<para>The recipes in this section of the cookbook cover how to create
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your own effects as well as how to apply Clutter's effects.</para>
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<section>
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<title>Creating effects using the abstract effect classes</title>
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<tip>
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<para>One of the original design goals of Clutter was to abstract
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the complexity of GL. However, the effects API partially circumvents
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these abstractions, to give you finer-grained access to the
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graphics pipeline. Therefore, if you want to write your own effects,
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some understanding of Cogl, OpenGL, and general graphics programming
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is essential.</para>
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</tip>
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<para>Each abstract effect class is tailored to modifying different
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aspects of an actor, as explained below:</para>
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<itemizedlist>
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<listitem>
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<formalpara>
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<title><type>ClutterEffect</type></title>
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<para>If you're just using the Clutter and Cogl APIs to
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decorate an actor, this is simplest type of effect to
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implement.</para>
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</formalpara>
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<para>Subclassing <type>ClutterEffect</type> enables you to
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"wrap" how an actor is painted, by injecting some code before
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and/or after the actor's own <function>paint()</function>
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implementation.</para>
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<note>
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<para>This is the preferred way to modify how an actor is
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painted, short of creating your own actor subclass.</para>
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</note>
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<para><emphasis>Subclasses of
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<type>ClutterEffect</type></emphasis>:</para>
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<itemizedlist>
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<listitem>
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<formalpara>
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<title><type>ClutterOffscreenEffect</type></title>
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<para>Use this class as a basis if you need GL textures
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for your effect.</para>
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</formalpara>
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<para>GL textures are required for effects which need
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an offscreen framebuffer. The offscreen framebuffer is
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used to store a modified rendering of an actor (e.g.
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with its colors altered or with deformed geometry).
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This buffer is then redirected to a texture in the
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stage window.</para>
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<para>An example is <type>ClutterBlurEffect</type>,
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which uses a GLSL fragment shader to blur an
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actor's appearance in an offscreen framebuffer.</para>
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<para><emphasis>Subclasses of
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<type>ClutterOffscreenEffect</type></emphasis>:</para>
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<itemizedlist>
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<listitem>
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<formalpara>
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<title><type>ClutterDeformEffect</type></title>
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<para>Use this base class if you want to modify
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an actor's geometry, at the level of individual
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vertices.</para>
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</formalpara>
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<para><type>ClutterDeformEffect</type> removes the
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complexity of dealing with vertex-based deformations
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at the OpenGL level, instead enabling you to easily plug
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a deformation callback into the graphics pipeline.</para>
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<para>If you are writing your own deform effects,
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a good example to work from is
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<type>ClutterPageTurnEffect</type>.</para>
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<para>There is also a
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<link linkend="effects-custom-deform">recipe which
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explains how to implement a simple custom deform
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effect</link> (a page fold).</para>
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</listitem>
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<listitem>
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<formalpara>
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<title><type>ClutterShaderEffect</type></title>
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<para>Use this if you want to apply custom
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GLSL vertex or fragment shaders to your actors.</para>
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</formalpara>
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<para>Writing <type>ClutterShaderEffects</type> gives
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you very fine-grained control over the GL pipeline.
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However, this makes them the most complex
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effects to implement.</para>
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<tip>
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<para>If you want to write your own GLSL shaders, the
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<ulink url="http://www.opengl.org/documentation/glsl/">GLSL
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specification</ulink> is a good starting point.</para>
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</tip>
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</listitem>
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</itemizedlist>
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</listitem>
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</itemizedlist>
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</listitem>
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</itemizedlist>
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</section>
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<section id="effects-introduction-using-the-built-in-effects">
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<title>Using the built-in effects</title>
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<para>Clutter comes with a number of built-in effects
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which can easily be applied to your actors. This section
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explains how to do this.</para>
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<para>First, create an actor. For this
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example, we use a texture loaded with an image:</para>
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<informalexample>
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<programlisting>
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/* filename could be set from command line or constant */
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gchar *filename;
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/* create a texture */
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ClutterActor *texture = clutter_texture_new ();
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/* ...set texture size, keep aspect ratio etc... */
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/* NB ignoring missing file errors here for brevity */
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clutter_texture_set_from_file (CLUTTER_TEXTURE (texture),
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filename,
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NULL);
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/* ...add texture to the stage... */
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</programlisting>
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</informalexample>
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<para>Next, create an instance of an effect; here, we're
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creating a <type>ClutterColorizeEffect</type> with a pink tint:</para>
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<informalexample>
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<programlisting>
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ClutterColor *pink = clutter_color_new (230, 187, 210, 255);
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ClutterEffect *effect = clutter_colorize_effect_new (pink);
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</programlisting>
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</informalexample>
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<para>Finally, apply the effect to the actor:</para>
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<informalexample>
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<programlisting>
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clutter_actor_add_effect (texture, effect);
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</programlisting>
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</informalexample>
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<para>The result in this case is an image colorized with
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a pink tint, like this:</para>
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<screenshot>
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<mediaobject>
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<imageobject>
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<imagedata format="PNG"
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fileref="images/effects-built-in.png" />
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</imageobject>
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<alt>
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<para>Applying a <type>ClutterColorizeEffect</type>
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to a texture loaded with an image (drawing by
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Madeleine Smith)</para>
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</alt>
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</mediaobject>
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</screenshot>
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<para>The same set of steps applies for any of the built-in
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Clutter effects. Your own custom effects classes should also
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behave in a similar way: constructors should return
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<type>ClutterEffect</type> instances so your effect can
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be added to an actor through the standard API.</para>
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<para>One further thing worth mentioning is that because an
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effect is a GObject, any properties you expose for your effect
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can be animated via implicit animations,
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<type>ClutterAnimator</type> or <type>ClutterState</type>. For
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example, the <type>ClutterPageTurnEffect</type> can be animated
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by manipulating its <varname>period</varname> property. An example
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of how to do this for your own effect is given in the
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<link linkend="effects-custom-deform">custom deform effect
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recipe</link>.</para>
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<para>The full code for the <type>ClutterColorizeEffect</type>
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example is below.</para>
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<example id="effects-introduction-example-1">
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<title>Applying a <type>ClutterColorizeEffect</type> to
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a texture loaded with an image</title>
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<programlisting>
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<xi:include href="examples/effects-built-in.c" parse="text">
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<xi:fallback>a code sample should be here... but isn't</xi:fallback>
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</xi:include>
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</programlisting>
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</example>
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</section>
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</section>
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<section id="effects-custom-deform">
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<title>Creating and animating a custom <type>ClutterDeformEffect</type></title>
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<section>
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<title>Problem</title>
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<para>You want to deform an actor's geometry: for example,
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to make it appear stretched, twisted or folded.</para>
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<para>This recipe demonstrates how to do this with a simple page
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fold effect, which folds one half of the actor over its other half.</para>
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</section>
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<section id="effects-custom-deform-solution">
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<title>Solution</title>
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<para>Subclass <type>ClutterDeformEffect</type> and
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implement a <function>deform_vertex()</function> function
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to modify the actor's vertices.</para>
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<para>The signature for <function>deform_vertex()</function>
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is:</para>
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<informalexample>
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<programlisting>
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void
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deform_vertex (ClutterDeformEffect *effect,
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gfloat width,
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gfloat height,
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CoglTextureVertex *vertex);
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</programlisting>
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</informalexample>
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<para>The <varname>width</varname> and <varname>height</varname>
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are the width and height of the target material, stored in
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the offscreen buffer. Usually the target material's size will
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match the actor's transformed size; however, if the effect
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implements <function>create_texture()</function>, the target
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material's size may differ from the actor's transformed size.</para>
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<para>The <varname>vertex</varname> contains the position
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and color of a vertex, to be deformed by your effect.
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Your <function>deform_vertex()</function>
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function should modify the member variables of this
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<type>CoglTextureVertex</type> in place. Usually, this will
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mean modifying the <varname>x</varname>, <varname>y</varname>
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and <varname>y</varname> member variables of the vertex,
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which describe its position in 3D space.</para>
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<para>The example function below, taken from
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<link linkend="effects-custom-deform-example-2">the
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full example</link>, applies a transformation to vertices falling
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in the "right-hand" half of the actor (i.e. vertices with an
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<varname>x</varname> value greater than or equal to half the
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width of the actor).</para>
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<informalexample>
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<programlisting>
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static void
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cb_page_fold_effect_deform_vertex (ClutterDeformEffect *effect,
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gfloat width,
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gfloat height,
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CoglTextureVertex *vertex)
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{
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CbPageFoldEffectPrivate *priv = CB_PAGE_FOLD_EFFECT (effect)->priv;
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/* the rotation angle is modified by the percentage progress of the fold,
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* as represented by the period variable
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*/
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gfloat radians = (priv->angle * priv->period) / (180.0f / G_PI);
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/* rotate from the center of the actor on the y axis */
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gfloat adjusted_x = vertex->x - (width / 2);
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/* only rotate vertices to the right of the middle of the actor */
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if (adjusted_x >= 0.0)
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{
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vertex->x = (vertex->z * sin (radians))
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+ (adjusted_x * cos (radians))
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+ width / 2;
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/* NB add 1 to z to prevent "z fighting"; otherwise, when fully-folded
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* the image has "stripes" where vertices from the folded part
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* of the actor interfere with vertices from the unfolded part
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*/
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vertex->z = (vertex->z * cos (radians))
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+ (adjusted_x * sin (radians))
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+ 1;
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}
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/* adjust depth of all vertices so they fit inside the actor while folding;
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* this has the effect of making the image smaller within the texture,
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* but does produce a cleaner fold animation
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*/
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vertex->z -= width / 2;
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}
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</programlisting>
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</informalexample>
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<para>Note that this effect has two properties set in its
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constructor or through setters:</para>
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<orderedlist>
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<listitem>
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<para><varname>angle</varname>, representing the angle of
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the full fold; for the actor to fully fold in half, this
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would be set to 180.0</para>
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</listitem>
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<listitem>
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<para><varname>period</varname>, representing the percentage
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of the fold to apply</para>
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</listitem>
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</orderedlist>
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<para>As well as rotating the vertex, the
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<function>deform_vertex()</function> function also shifts
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the <varname>z</varname> coordinate "up" by 1
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(towards the viewpoint) for vertices on the right-hand side of the
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actor. This is so that the "folded over" vertices
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are above vertices on the left-hand side. Without this small
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shift, the vertices interfere with each other, which can cause striping
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artefacts.</para>
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<para><emphasis>All</emphasis> vertices are also shifted "down",
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so that the the folding part of the actor remains within the texture.
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Otherwise the part which is folding may be clipped to the allocation of
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the actor.</para>
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<para>This effect can now be applied to an actor, using the
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approach
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<link linkend="effects-introduction-using-the-built-in-effects">outlined
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in the introduction</link>. The result looks like this when
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<varname>period</varname> is set to 0.25 and <varname>angle</varname>
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to 180.0 (i.e. the page is folded by 45 degrees):</para>
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<screenshot>
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<mediaobject>
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<imageobject>
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<imagedata format="PNG"
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fileref="images/effects-custom-deform.png" />
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</imageobject>
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<alt>
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<para>Applying a custom <type>ClutterDeformEffect</type>
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to a texture loaded with an image</para>
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</alt>
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</mediaobject>
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</screenshot>
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<para>Because the effect is a GObject which exposes its
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properties, it can easily be animated, as described in
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<link linkend="effects-custom-deform-discussion-animating">the
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discussion section</link>.</para>
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</section>
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<section id="effects-custom-deform-discussion">
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<title>Discussion</title>
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<para>A deform effect processes an actor as follows:</para>
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<itemizedlist>
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<listitem>
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<para>The actor is divided into a series of
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triangular tiles. The number of
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horizontal and vertical tiles is configurable;
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more tiles implies more vertices. See
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<link linkend="effects-custom-deform-discussion-tiles">this
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section</link> for more details about tiles.</para>
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</listitem>
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<listitem>
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<para>The position of each vertex of each
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tile is then modified (or not) by the
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<function>deform_vertex()</function> function. In this
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function, you can change the vertex's position
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(<varname>x</varname>, <varname>y</varname>,
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<varname>z</varname> coordinates). You can also
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modify the color at the vertex if desired.</para>
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<para>The resulting deformed vertices are stored
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in an offscreen buffer.</para>
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</listitem>
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<listitem>
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<para>Once the deformation has been applied to
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all vertices, the content of the offscreen buffer
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is painted at the onscreen position of the actor.</para>
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</listitem>
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</itemizedlist>
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<para>You may find it useful to visualise this process by imagining
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your actor's surface as a net, composed of triangles. (Something
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like a fishing net, not a mathematical one.) At each corner of
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each triangle is a marble; and between each pair of corners
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is an infinitely flexible length of elastic. Moving a marble
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doesn't change the position of its neighbours; it just stretches
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or relaxes the elastic.</para>
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<para>In this analogy, the marbles are the vertices; and the
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surfaces between the marbles, bordered by triangles of
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elastic, are the tiles. More triangles (tiles) means more
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marbles (vertices).</para>
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<para>When you create a <type>ClutterDeformEffect</type>,
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think of it as specifying movements of marbles in the net.
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Changing the position of a vertex corresponds to moving a marble
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up/down (-/+ <varname>y</varname> position), left/right
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(-/+ <varname>x</varname> position) or away/towards
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you (-/+ <varname>z</varname> position) (ignoring color for the
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moment).</para>
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<para>Now imagine that you are asked to fold the whole net of
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marbles; but you can't just grab the edge of the net and pull
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it over: you can only move one marble at a time. However, once moved,
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each marble magically stays where you put it in 3D space.</para>
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<para>To do this, you could project where each marble would be if
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you could fold the whole sheet in one go; then move the
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marbles one by one to their projected positions. Even though
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you'd be moving the marbles one at a time, it would eventually
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look as though you'd folded the whole net with a single movement.</para>
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<para>When you write a <type>ClutterDeformEffect</type>, you have
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to accomplish a similar feat: change the shape of an actor
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by individually modifying the positions of points on its surface. In
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most cases, your <function>deform_vertex()</function> implementation
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can take advantage of an existing geometric transformation
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method to achieve this. (For example, the page fold in this recipe
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is based on equations from p.412 of <citetitle pubwork="book">Computer
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Graphics (C Version), 2nd Edition</citetitle> by Hearn and
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Baker, 1996.)</para>
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<section>
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<title>Customising the back material</title>
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<para>When you set up a deform effect, you
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can optionally specify a material to use for the "back" of
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any actor it is applied to.</para>
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<para>If you think of an actor as a sheet of paper with a
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picture on it, specifying a back is similar to turning the
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sheet of paper over (rotating it around the
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<varname>y</varname> axis) and drawing another picture on
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the other side. If you then folded or twisted the paper,
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you would be able to see parts of the pictures on both the
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front and back of the paper.</para>
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<para>Similarly, during deformation of an actor, if any
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vertices of the actor are deformed such that the actor's surface
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is folded or twisted over itself, parts of its back
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become visible. If you set a back material, you will see parts
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of that where the surface is folded over. If you don't set a back
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material, you will instead see mirror images of parts of the actor's
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front: as if the actor was flexible stained glass, rather than paper.
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You can see this if you watch the animation in
|
|
<link linkend="effects-custom-deform-discussion-animating">this
|
|
section</link>.</para>
|
|
|
|
<para>The back material should be an instance of
|
|
<type>CoglMaterial</type>. You can either create this via
|
|
the Cogl API directly; or indirectly through the Clutter API
|
|
(for example, by getting the material from a
|
|
<type>ClutterTexture</type>). The code below gives an example
|
|
of how to do the latter:</para>
|
|
|
|
<informalexample>
|
|
<programlisting>
|
|
<![CDATA[
|
|
/* create a texture */
|
|
ClutterActor *back = clutter_texture_new ();
|
|
clutter_texture_set_keep_aspect_ratio (CLUTTER_TEXTURE (back), TRUE);
|
|
clutter_actor_set_width (back, 400);
|
|
|
|
/* load image into texture (ignoring errors for brevity) */
|
|
clutter_texture_set_from_file (CLUTTER_TEXTURE (back),
|
|
back_image_file,
|
|
NULL);
|
|
|
|
/* get a handle to the texture's Cogl material */
|
|
CoglHandle material = clutter_texture_get_cogl_material (CLUTTER_TEXTURE (back));
|
|
|
|
/* cast the effect to ClutterDeformEffect and set its back material
|
|
* to the handle
|
|
*/
|
|
clutter_deform_effect_set_back_material (CLUTTER_DEFORM_EFFECT (effect),
|
|
material);
|
|
]]>
|
|
</programlisting>
|
|
</informalexample>
|
|
|
|
<para>See the <type>ClutterDeformEffect</type> API reference
|
|
for more details about back materials.</para>
|
|
|
|
<para>Here's a screenshot of the
|
|
<link linkend="effects-custom-deform-example-3">example</link>
|
|
with the addition of a back material, folded at an angle
|
|
of 60 degrees:</para>
|
|
|
|
<screenshot>
|
|
<mediaobject>
|
|
<imageobject>
|
|
<imagedata format="PNG"
|
|
fileref="images/effects-custom-deform-back-material.png" />
|
|
</imageobject>
|
|
<alt>
|
|
<para>Applying a custom <type>ClutterDeformEffect</type>
|
|
to a texture loaded with an image</para>
|
|
</alt>
|
|
</mediaobject>
|
|
</screenshot>
|
|
|
|
</section>
|
|
|
|
<section id="effects-custom-deform-discussion-animating">
|
|
<title>Animating a custom deform effect</title>
|
|
|
|
<para>Clutter's animation API can animate any GObject which
|
|
exposes its properties. In the case of the page fold effect,
|
|
we can expose the <varname>period</varname> property using
|
|
standard GObject property installation:</para>
|
|
|
|
<informalexample>
|
|
<programlisting>
|
|
/* GObject class init */
|
|
static void
|
|
cb_page_fold_effect_class_init (CbPageFoldEffectClass *klass)
|
|
{
|
|
GParamSpec *pspec;
|
|
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
|
|
|
|
/* ...other class setup code... */
|
|
|
|
/* expose the period as a GObject property */
|
|
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);
|
|
|
|
/* ...install other properties... */
|
|
}
|
|
</programlisting>
|
|
</informalexample>
|
|
|
|
<para>We also add a <function>get_property()</function>
|
|
implementation, as well as a setter (see
|
|
<link linkend="effects-custom-deform-example-2">the full
|
|
GObject implementation</link> for details).</para>
|
|
|
|
<para>Then set up an animation for the property; in this case,
|
|
using a <type>ClutterState</type>:</para>
|
|
|
|
<informalexample>
|
|
<programlisting>
|
|
ClutterEffect *effect = cb_page_fold_effect_new (180.0, 0.0);
|
|
|
|
ClutterState *transitions = clutter_state_new ();
|
|
clutter_state_set_duration (transitions, NULL, NULL, 500);
|
|
|
|
clutter_state_set (transitions, NULL, "unfolded",
|
|
effect, "period", CLUTTER_LINEAR, 0.0,
|
|
NULL);
|
|
|
|
clutter_state_set (transitions, NULL, "folded",
|
|
effect, "period", CLUTTER_LINEAR, 1.0,
|
|
NULL);
|
|
</programlisting>
|
|
</informalexample>
|
|
|
|
<para>To start the animation, warp the <type>ClutterState</type>
|
|
into its <emphasis>"unfolded"</emphasis> state, then set it to
|
|
<emphasis>"folded"</emphasis>:</para>
|
|
|
|
<informalexample>
|
|
<programlisting>
|
|
/* this changes state instantaneously */
|
|
clutter_state_warp_to_state (transitions, "unfolded");
|
|
|
|
/* this starts an animation to the state */
|
|
clutter_state_set_state (transitions, "folded");
|
|
</programlisting>
|
|
</informalexample>
|
|
|
|
<para>Note that the
|
|
<link linkend="effects-custom-deform-example-3">full code
|
|
sample</link> is slightly more complex, as it triggers state
|
|
changes when a mouse button is pressed on the texture. There is
|
|
also a third "partially folded" state (used to create
|
|
the screenshot for the
|
|
<link linkend="effects-custom-deform-solution">previous
|
|
section</link>).</para>
|
|
|
|
<para>Here's what the resulting animation looks like:</para>
|
|
|
|
<inlinemediaobject>
|
|
<videoobject>
|
|
<videodata fileref="videos/effects-custom-deform.ogv"/>
|
|
</videoobject>
|
|
<alt>
|
|
<para>Video showing animation of a custom deform effect
|
|
on a texture</para>
|
|
</alt>
|
|
</inlinemediaobject>
|
|
|
|
</section>
|
|
|
|
<section id="effects-custom-deform-discussion-tiles">
|
|
<title>Tiles</title>
|
|
|
|
<para>A <type>ClutterDeformEffect</type> divides the actor
|
|
being deformed into a number of tiles: the larger the number
|
|
of tiles, the larger the number of vertices to be manipulated
|
|
by the effect. Increasing the number of tiles increases the number of
|
|
vertex computations required, which can slow down animations;
|
|
at the same time, finer-grained tiles can make an effect appear
|
|
smoother, particularly when animated.</para>
|
|
|
|
<para>Most of the time, the default number
|
|
of tiles in the <varname>x</varname> and <varname>y</varname>
|
|
axes should suffice. You can get the current number of
|
|
tiles associated with an effect with:</para>
|
|
|
|
<informalexample>
|
|
<programlisting>
|
|
<![CDATA[
|
|
guint x_tiles;
|
|
guint y_tiles;
|
|
|
|
/* effect must be a subclass of ClutterDeformEffect */
|
|
clutter_deform_effect_get_n_tiles (CLUTTER_DEFORM_EFFECT (effect),
|
|
&x_tiles,
|
|
&y_tiles);
|
|
]]>
|
|
</programlisting>
|
|
</informalexample>
|
|
|
|
<para>However, if an effect produces jerky or fragmented output,
|
|
you want to tweak the number of tiles. Use the
|
|
<function>clutter_deform_effect_set_n_tiles()</function> function
|
|
to do this:</para>
|
|
|
|
<informalexample>
|
|
<programlisting>
|
|
/* 64 tiles in both axes */
|
|
guint x_tiles = 64;
|
|
guint y_tiles = 64;
|
|
|
|
clutter_deform_effect_set_n_tiles (CLUTTER_DEFORM_EFFECT (effect),
|
|
x_tiles,
|
|
y_tiles);
|
|
</programlisting>
|
|
</informalexample>
|
|
|
|
</section>
|
|
|
|
</section>
|
|
|
|
<section>
|
|
<title>Full example</title>
|
|
|
|
<para>This example consists of three files:</para>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para><link linkend="effects-custom-deform-example-1">A header
|
|
file</link> for the <type>CbPageFoldEffect</type> GObject.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><link linkend="effects-custom-deform-example-2">The
|
|
code file</link> implementing <type>CbPageFoldEffect</type>.</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para><link linkend="effects-custom-deform-example-3">A short
|
|
sample application</link> which applies a <type>CbPageFoldEffect</type>
|
|
instance to an actor and animates the fold when the actor is
|
|
clicked.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
|
|
<para>As Clutter effect subclasses are written using GObject,
|
|
you might find <link linkend="actors-composite">this recipe</link>
|
|
(which goes into GObject in more detail) a useful introduction.</para>
|
|
|
|
<example id="effects-custom-deform-example-1">
|
|
<title><filename>cb-page-fold-effect.h</filename> (header file)</title>
|
|
<programlisting>
|
|
<xi:include href="examples/cb-page-fold-effect.h" parse="text">
|
|
<xi:fallback>a code sample should be here... but isn't</xi:fallback>
|
|
</xi:include>
|
|
</programlisting>
|
|
</example>
|
|
|
|
<example id="effects-custom-deform-example-2">
|
|
<title><filename>cb-page-fold-effect.c</filename> (code file)</title>
|
|
<programlisting>
|
|
<xi:include href="examples/cb-page-fold-effect.c" parse="text">
|
|
<xi:fallback>a code sample should be here... but isn't</xi:fallback>
|
|
</xi:include>
|
|
</programlisting>
|
|
</example>
|
|
|
|
<example id="effects-custom-deform-example-3">
|
|
<title>Application which uses <type>CbPageFoldEffect</type>
|
|
to do animated folding of a <type>ClutterTexture</type></title>
|
|
<programlisting>
|
|
<xi:include href="examples/effects-custom-deform.c" parse="text">
|
|
<xi:fallback>a code sample should be here... but isn't</xi:fallback>
|
|
</xi:include>
|
|
</programlisting>
|
|
</example>
|
|
|
|
</section>
|
|
|
|
</section>
|
|
|
|
</chapter>
|