Merge "Doc change: fixing renderscript samples" into honeycomb

		            resources/samples/NotePad "Note Pad" \

		-samplecode $(sample_dir)/SampleSyncAdapter \

		            resources/samples/SampleSyncAdapter "Sample Sync Adapter" \

		-samplecode frameworks/base/libs/rs/java \

		            resources/samples/Renderscript "Renderscript" \

		-samplecode $(sample_dir)/SearchableDictionary \

		            resources/samples/SearchableDictionary "Searchable Dictionary v2" \

		-samplecode $(sample_dir)/SipDemo \

          <ol>

            <li><a href="#native-api">Native Renderscript APIs</a></li>

            <li><a href="#reflective-api">Reflective layer APIs</a></li>

            <li><a href="#reflective-api">Reflected layer APIs</a></li>

            <li><a href="#graphics-api">Graphics APIs</a></li>

          </ol>

          </ol>

        </li>

      </ol>

      <h2>Related Samples</h2>

      <ol>

            <li><a href="{@docRoot}resources/samples/Renderscript/Balls/index.html">Balls</a></li>

            <li><a href="{@docRoot}resources/samples/Renderscript/Fountain/index.html">Fountain</a></li>

            <li><a href="{@docRoot}resources/samples/Renderscript/HelloCompute/index.html">Hello Compute</a></li>

            <li><a href="{@docRoot}resources/samples/Renderscript/HelloWorld/index.html">Hello World</a></li>

            <li><a href="{@docRoot}resources/samples/Renderscript/Samples/index.html">Samples</a></li>

          </ol>

    </div>

  </div>

  <p>The Renderscript system offers high performance 3D rendering and mathematical computations at

  <p>The Renderscript system offers high performance 3D rendering and mathematical computation at

  the native level. The Renderscript APIs are intended for developers who are comfortable with

  developing in C (C99 standard) and want to maximize performance in their applications. The

  Renderscript system improves performance by running as native code on the device, but it also

  intermediate code.</p>

  <p>The disadvantage of the Renderscript system is that it adds complexity to the development and

  debugging processes and is not a substitute for the Android system APIs. It is a portable native

  language with pointers and explicit resource management. The target use is for performance

  critical code where the existing Android APIs are not sufficient. If what you are rendering or

  computing is very simple and does not require much processing power, you should still use the

  Android APIs for ease of development. Debugging visibility can be limited, because the

  debugging processes. Debugging visibility can be limited, because the

  Renderscript system can execute on processors other than the main CPU (such as the GPU), so if

  this occurs, debugging becomes more difficult. Remember the tradeoffs between development and

  this occurs, debugging becomes more difficult. The target use is for performance

  critical code where the traditional framework APIs (such as using {@link android.opengl}) are not sufficient.

  If what you are rendering or computing is very simple and does not require much processing power, you should still use the

  traditional framework APIs for ease of development. Remember the tradeoffs between development and

  debugging complexity versus performance when deciding to use Renderscript. </p>

  <p>For an example of Renderscript in action, see the 3D carousel view in the Android 3.0 versions

  of Google Books and YouTube or install the Renderscript sample applications that are shipped with

  the SDK in <code>&lt;sdk_root&gt;/platforms/android-3.0/samples</code>.</p>

  the SDK in <code>&lt;sdk_root&gt;/samples/android-11/Renderscript</code>.</p>

  <h2 id="overview">Renderscript System Overview</h2>

  <p>The Renderscript system adopts a control and slave architecture where the low-level native

  code is controlled by the higher level Android system that runs in the virtual machine (VM). When

  you use the Renderscript system, there are three layers of APIs that exist:</p>

  you use the Renderscript system, there are three layers that exist:</p>

  <ul>

    <li>The native Renderscript layer consists of the native Renderscript <code>.rs</code> files

    that you write to compute mathematical operations, render graphics, or both. This layer does

    the intensive computation or graphics rendering and returns the result back to the Android VM

    through the reflected layer.</li>

    <li>The native Renderscript layer consists of native libraries that are packaged with the SDK.

    The native Renderscript <code>.rs</code> files compute mathematical operations, render graphics,

    or both. This layer does the intensive computation or graphics rendering and returns the result

    back to the Android VM through the reflected layer.</li>

    <li>The reflected layer is a set of generated Android system classes (through reflection) based

    on the native layer interface that you define. This layer acts as a bridge between the native

    <li>The reflected layer is a set of generated Android framework classes reflected from

    the native Renderscript code that you wrote. This layer acts as a bridge between the native

    Renderscript layer and the Android system layer. The Android build tools automatically generate

    the APIs for this layer during the build process.</li>

    the classes for this layer during the build process. This layer also includes a set of Android

    framework APIs that provide the memory and resource allocation classes to support this layer.</li>

    <li>The Android system layer consists of your normal Android APIs along with the Renderscript

    <li>The Android system layer consists of the traditional framework APIs, which include the Renderscript

    APIs in {@link android.renderscript}. This layer handles things such as the Activity lifecycle

    management of your application and calls the native Renderscript layer through the reflected

    layer.</li>

    management of your application and calls the reflected layer to communicate with the native Renderscript code.</li>

  </ul>

  <p>To fully understand how the Renderscript system works, you must understand how the reflected

  layer is generated and how it interacts with the native Renderscript layer and Android system

  layer. The reflected layer provides the entry points into the native code, enabling the Android

  system code to give high level commands like, "rotate the view" or "filter the bitmap." It

  delegates all the heavy lifting to the native layer. To accomplish this, you need to create logic

  system to give high level commands like, "rotate the view" or "filter the bitmap" to the

  native layer, which does the heavy lifting. To accomplish this, you need to create logic

  to hook together all of these layers so that they can correctly communicate.</p>

  <p>At the root of everything is your Renderscript, which is the actual C code that you write and

  and graphics. A compute Renderscript does not do any graphics rendering while a graphics

  Renderscript does.</p>

  <p>When you create a Renderscript <code>.rs</code> file, an equivalent, reflective layer class,

  {@link android.renderscript.ScriptC}, is generated by the build tools and exposes the native

  functions to the Android system. This class is named

  <code><em>ScriptC_renderscript_filename</em></code>. The following list describes the major

  components of your native Renderscript code that is reflected:</p>

  <p>When you create Renderscript <code>.rs</code> files, equivalent, reflected classes

  are generated by the build tools and expose the native functions and data types and structures

  to the Android system. The following list describes the major components of your native Renderscript

  code that is reflected:</p>

  <ul>

    <li>The non-static functions in your Renderscript (<code>.rs</code> file) are reflected into

    <li>Any non-static, global Renderscript variables are reflected into

    <code><em>ScriptC_renderscript_filename</em></code>.

    Accessor methods are generated, so the Android system layer can access the values.

    The <code>get()</code> method comes with a one-way communication restriction. 

    The Android system layer always caches the last value that is set and returns that during a call to get.

    If the native Renderscript code has changed the value, the change does propagate back to the Android system layer

    for efficiency. If the global variables are initialized in the native Renderscript code, those values are used

    to initialize the Android system versions. If global variables are marked as <code>const</code>,

    then a <code>set()</code> method is not generated.

    The <code>get</code> method comes with a one-way communication restriction. 

    The Android system layer always caches the last value that is set and returns that during a call to a <code>get<code> method.

    If the native Renderscript code changes the value, the change does not propagate back to the Android system layer.

    If the global variables are initialized in the native Renderscript code, those values are used

    to initialize the corresponding values in the Android system. If global variables are marked as <code>const</code>,

    then a <code>set</code> method is not generated.

    </li>

    <li>Structs are reflected into their own classes, one for each struct, into a class named

    Renderscripts should not directly set the exported global pointers.</li>

     </ul>

  <p>The Android system also has a corresponding Renderscript context object, {@link

  <p>The Android framework API also has a corresponding Renderscript context object, {@link

  android.renderscript.RenderScript} (for a compute Renderscript) or {@link

  android.renderscript.RenderScriptGL} (for a graphics Renderscript). This context object allows

  you to bind to the reflected Renderscript class, so that the Renderscript context knows what its

  corresponding native Renderscript is. If you have a graphics Renderscript context, you can also

  specify a variety of Programs (stages in the graphics pipeline) to tweek how your graphics are

  rendered. A graphics Renderscript context also needs a surface to render on, {@link

  android.renderscript.RSSurfaceView}, which gets passed into its constructor. When all three of

  the layers are connected, the Renderscript system can compute or render graphics.</p>

  android.renderscript.RSSurfaceView}, which gets passed into its constructor.</p>

  <h2 id="api">API overview</h2>

  because these functions are assumed to be running on a standard CPU. The Renderscript runtime

  chooses the best processor to execute the code, which may not be the CPU, so it cannot guarantee

  support for standard C libraries. What Renderscript does offer is an API that supports intensive

  computation with an extensive collection of math APIs. Some key features of the Renderscript APIs

  are:</p>

  computation with an extensive collection of math APIs. The following sections group the APIs

  into three distinct categories.</p>

  <h3 id="native-api">Native Renderscript APIs</h3>

  <p>The Renderscript headers are located in the <code>include</code> and

  <code>clang-include</code> directories in the

  <code>&lt;sdk_root&gt;/platforms/android-3.0/renderscript</code> directory of the Android SDK.

  <code>&lt;sdk_root&gt;/platforms/android-11/renderscript</code> directory of the Android SDK.

  The headers are automatically included for you, except for the graphics specific header,

  which you can define as follows:</p>

    <li>Graphics rendering functions</li>

    <li>Memory allocation request features</li>

    <li>Data types and structures to support the Renderscript system such as

    Vector types for defining two-, three-, or four-vectors.</li></li>

  </ul>

    Vector types for defining two-, three-, or four-vectors.</li>

  </ul>

  <h3 id="reflective-api">Reflective layer APIs</h3>

  <h3 id="reflective-api">Reflected layer APIs</h3>

  <p>These classes are not generated by the reflection process, and are actually part of the

  Android system APIs, but they are mainly used by the reflective layer classes to handle memory

  allocation and management for your Renderscript. You normally do not need to be call these classes

  directly.</p> 

  <p>These classes are mainly used by the reflected classes that are generated from your native Renderscript

  code. They allocate and manage memory for your Renderscript on the Android system side. 

  You normally do not need to call these classes directly.</p> 

  <p>Because of the constraints of the Renderscript native layer, you cannot do any dynamic

  memory allocation in your Renderscript <code>.rs</code> file.

  The Android system object, which at this point is just an empty shell, is eventually garbage collected.

  </p>

  <p>The following classes are mainly used by the reflective layer classes:</p>

  <p>The following classes are mainly used by the reflected layer classes:</p>

  <table>

    <tr>

      <td>

        An {@link android.renderscript.Element} is the most basic element of a memory type. An

        element represents one cell of a memory allocation. An element can have two forms: Basic or

        Complex. They are typically created from C structures that are used within Renderscript

        code and cannot contain pointers or nested arrays. The other common source of elements is

        bitmap formats.

        Complex. They are typically created from C structures in your Renderscript

        code during the reflection process. Elements cannot contain pointers or nested arrays. 

        The other common source of elements is bitmap formats.

        <p>A basic element contains a single component of data of any valid Renderscript data type.

        Examples of basic element data types include a single float value, a float4 vector, or a

      <td>rs_allocation</td>

      <td>

        An {@link android.renderscript.Allocation} provides the memory for applications. An {@link

        <p>An {@link android.renderscript.Allocation} provides the memory for applications. An {@link

        android.renderscript.Allocation} allocates memory based on a description of the memory that

        is represented by a {@link android.renderscript.Type}. The {@link

        android.renderscript.Type} describes an array of {@link android.renderscript.Element}s that

        is represented by a {@link android.renderscript.Type}. The type describes an array of elements that

        represent the memory to be allocated. Allocations are the primary way data moves into and

        out of scripts.

        out of scripts.</p>

        <p>Memory is user-synchronized and it's possible for allocations to exist in multiple

        memory spaces concurrently. For example, if you make a call to the graphics card to load a

        <p>Allocation data is uploaded in one of two primary ways: type checked and type unchecked.

        For simple arrays there are <code>copyFrom()</code> functions that take an array from the

        Android system code and copy it to the native layer memory store. Both type checked and

        Android system and copy it to the native layer memory store. Both type checked and

        unchecked copies are provided. The unchecked variants allow the Android system to copy over

        arrays of structures because it not support inherently support structures. For example, if

        arrays of structures because it does not support structures. For example, if

        there is an allocation that is an array n floats, you can copy the data contained in a

        float[n] array or a byte[n*4] array.</p>

      </td>

  state is taken from the bind points as set in the {@link android.renderscript.RenderScriptGL}

  bind methods in the control environment (VM environment).</p>

  <p>For example, you can define this at the top of your native Renderscript code:</p>

  <p>For example, you can define this at the top of your native graphics Renderscript code:</p>

  <pre>

#pragma stateVertex(parent)

#pragma stateStore(parent)

      <td>rs_program_vertex</td>

      <td>

        The Renderscript vertex program, also known as a vertex shader, describes the stage in the

        <p>The Renderscript vertex program, also known as a vertex shader, describes the stage in the

        graphics pipeline responsible for manipulating geometric data in a user-defined way. The

        object is constructed by providing Renderscript with the following data:

        object is constructed by providing Renderscript with the following data:</p>

        <ul>

          <li>An Element describing its varying inputs or attributes</li>

          inputs</li>

        </ul>

        <p>Once the program is created, bind it to the graphics context. It is then used for all

        <p>Once the program is created, bind it to the {@link android.renderscript.RenderScriptGL} 

        graphics context by calling 

        {@link android.renderscript.RenderScriptGL#bindProgramVertex bindProgramVertex()}. It is then used for all

        subsequent draw calls until you bind a new program. If the program has constant inputs, the

        user needs to bind an allocation containing those inputs. The allocation’s type must match

        the one provided during creation. The Renderscript library then does all the necessary

      <td>rs_program_fragment</td>

      <td>The Renderscript fragment program, also known as the fragment shader, is responsible for

      <td><p>The Renderscript fragment program, also known as the fragment shader, is responsible for

      manipulating pixel data in a user-defined way. It’s constructed from a GLSL shader string

      containing the program body, textures inputs, and a Type object describing the constants used

      by the program. Like the vertex programs, when an allocation with constant input values is

      rsgAllocationSyncAll so it could send the new values to hardware. Communication between the

      vertex and fragment programs is handled internally in the GLSL code. For example, if the

      fragment program is expecting a varying input called varTex0, the GLSL code inside the

      program vertex must provide it.

      program vertex must provide it.</p>

      <p>  To bind shader constructs to the this Program, declare a struct containing the necessary shader constants in your native Renderscript code.

  This struct is generated into a reflected class that you can use as a constant input element

  during the Program's creation. It is an easy way to create an instance of this struct as an allocation.

      <td>rs_program_store</td>

      <td>The Renderscript ProgramStore contains a set of parameters that control how the graphics

      hardware writes to the framebuffer. It could be used to enable/disable depth writes and

      hardware writes to the framebuffer. It could be used to enable and disable depth writes and

      testing, setup various blending modes for effects like transparency and define write masks

      for color components.</td>

    </tr>

  <ol>

    <li>Analyze your application's requirements and figure out what you want to develop with

    Renderscript. To take full advantage of Renderscript, you want to use it when the computation

    or graphics performance you're getting with the normal Android system APIs is

    Renderscript. To take full advantage of the Renderscript system, you want to use it when the computation

    or graphics performance you're getting with the traditional framework APIs is

    insufficient.</li>

    <li>Design the interface of your Renderscript code and implement it using the native

    Renderscript APIs that are included in the Android SDK in

    <code>&lt;sdk_root&gt;/platforms/android-3.0/renderscript</code>.</li>

    <code>&lt;sdk_root&gt;/platforms/android-11/renderscript</code>.</li>

    <li>Create an Android project as you would normally, in Eclipse or with the

    <code>android</code> tool.</li>

    <li>Place your Renderscript files in <code>src</code> folder of the Android project so that the

    build tools can generate the reflective layer classes.</li>

    build tools can generate the reflected layer classes.</li>

    <li>Create your application, calling the Renderscript through the reflected class layer when

    you need to.</li>

    <li>Build, install, and run your application as you would normally.</li>

  </ol>

  <p>To see how a simple Renderscript application is put together, see <a href="#hello-world">The

  Hello World Renderscript Graphics Application</a>. The SDK also ships with many Renderscript

  samples in the<code>&lt;sdk_root&gt;/samples/android-3.0/</code> directory.</p>

  <p>To see how a simple Renderscript application is put together, see the 

  <a href="{@docRoot}resources/samples/Renderscript/index.html">Renderscript samples</a>

  and <a href="#hello-graphics">The Hello Graphics Application</a> section of the documentation.</p>

  <h3 id="hello-graphics">The Hello Graphics Application</h3>

  <p>This small application demonstrates the structure of a simple Renderscript application. You

  can model your Renderscript application after the basic structure of this application. You can

  find the complete source in the SDK in the

  <code>&lt;android-sdk&gt;/platforms/android-3.0/samples/HelloWorldRS directory</code>. The

  <code>&lt;android-sdk&gt;/samples/android-11/HelloWorldRS directory</code>. The

  application uses Renderscript to draw the string, "Hello World!" to the screen and redraws the

  text whenever the user touches the screen at the location of the touch. This application is only

  a demonstration and you should not use the Renderscript system to do something this trivial. The

    screen.</li>

    <li>

      <p>The <code>&lt;project_root&gt;/gen</code> directory contains the reflective layer classes

      <p>The <code>&lt;project_root&gt;/gen</code> directory contains the reflected layer classes

      that are generated by the Android build tools. You will notice a

      <code>ScriptC_helloworld</code> class, which is the reflective version of the Renderscript

      and contains the entry points into the <code>helloworld.rs</code> native code. This file does

    </li>

  </ul>

  <p>Each file has its own distinct use. The following section demonstrates in detail how the

  sample works:</p>

  <p>Each file has its own distinct use. The following files comprise the main parts of the sample and

  demonstrate in detail how the sample works:</p>

  <dl>

    <dt><code>helloworld.rs</code></dt>

    <dd>This class is generated by the Android build tools and is the reflected version of the

    <code>helloworld.rs</code> Renderscript. It provides a a high level entry point into the

    <code>helloworld.rs</code> native code by defining the corresponding methods that you can call

    from Android system APIs.</dd>

    from the traditional framework APIs.</dd>

    <dt><code>helloworld.bc</code> bytecode</dt>

      en: 'An application for saving notes. Similar (but not identical) to the <a href="/resources/tutorials/notepad/index.html">Notepad tutorial</a>.'

    }

  },

  {

    tags: ['sample', 'new'],

    path: 'samples/Renderscript/index.html',

    title: {

      en: 'Renderscript'

    },

    description: {

      en: 'A set of samples that demonstrate how to use various features of the Renderscript APIs.'

    }

  },

  {

    tags: ['sample', 'accountsync'],

    path: 'samples/SampleSyncAdapter/index.html',

<p>A brute force physics simulation that renders many balls onto the screen and moves them according to user touch and gravity.</p>

 No newline at end of file

<p>An example that renders many dots on the screen that follow a user's touch. The dots fall 

to the bottom of the screen when the user releases the finger.</p>