am 8b93ba78: am cd76edb9: Merge "docs: OpenGL ES 3.0 dev guide update" into jb-mr2-dev

            <span class="en">Canvas and Drawables</span>

          </a></li>

        <li><a href="<?cs var:toroot ?>guide/topics/graphics/opengl.html">

            <span class="en">OpenGL</span>

            <span class="en">OpenGL ES</span>

          </a></li>

        <li><a href="<?cs var:toroot ?>guide/topics/graphics/hardware-accel.html">

            <span class="en">Hardware Acceleration</span>

page.title=OpenGL

page.title=OpenGL ES

page.tags="games"

@jd:body

    <ol>

      <li><a href="#basics">The Basics</a>

        <ol>

           <li><a href="#packages">OpenGL packages</a></li>

          <li><a href="#packages">OpenGL ES packages</a></li>

        </ol>

      <li><a href="#manifest">Declaring OpenGL Requirements</a></li>

      </li>

      <li><a href="#coordinate-mapping">Mapping Coordinates for Drawn Objects</a>

        <ol>

          <li><a href="#proj-es1">Projection and camera in ES 1.0</a></li>

          <li><a href="#proj-es1">Projection and camera in ES 2.0</a></li>

          <li><a href="#proj-es2">Projection and camera in ES 2.0 and higher</a></li>

        </ol>

      </li>

      <li><a href="#faces-winding">Shape Faces and Winding</li>

      <li><a href="#faces-winding">Shape Faces and Winding</a></li>

      <li><a href="#compatibility">OpenGL Versions and Device Compatibility</a>

        <ol>

          <li><a href="#textures">Texture compression support</a></li>

          <li><a href="#gl-extension-query">Determining OpenGL Extensions</a></li>

          <li><a href="#gl-extension-query">Determining OpenGL extensions</a></li>

          <li><a href="#version-check">Checking OpenGL ES Version</a></li>

        </ol>

      </li>

      <li><a href="#choosing-version">Choosing an OpenGL API Version</a></li>

      <li><a href="http://www.khronos.org/opengles/">OpenGL ES</a></li>

      <li><a href="http://www.khronos.org/opengles/1_X/">OpenGL ES 1.x Specification</a></li>

      <li><a href="http://www.khronos.org/opengles/2_X/">OpenGL ES 2.x specification</a></li>

      <li><a href="http://www.khronos.org/opengles/3_X/">OpenGL ES 3.x specification</a></li>

    </ol>

  </div>

</div>

<p>Android includes support for high performance 2D and 3D graphics with the Open Graphics Library

(OpenGL), specifically, the OpenGL ES API. OpenGL is a cross-platform graphics API that specifies a

(OpenGL®), specifically, the OpenGL ES API. OpenGL is a cross-platform graphics API that specifies a

standard software interface for 3D graphics processing hardware. OpenGL ES is a flavor of the OpenGL

specification intended for embedded devices. The OpenGL ES 1.0 and 1.1 API specifications have been

supported since Android 1.0. Beginning with Android 2.2 (API Level 8), the framework supports the

OpenGL ES 2.0 API specification.</p>

specification intended for embedded devices. Android supports several versions of the OpenGL ES

API:</p>

<ul>

  <li>OpenGL ES 1.0 and 1.1 - This API specification is supported by Android 1.0 and higher.</li>

  <li>OpenGL ES 2.0 - This API specification is supported by Android 2.2 (API level 8) and higher.

    </li>

  <li>OpenGL ES 3.0 - This API specification is supported by Android 4.3 (API level 18) and higher.

    </li>

</ul>

<p class="caution"><strong>Caution:</strong>

  Support of the OpenGL ES 3.0 API on a device requires an implementation of this graphics

  pipeline provided by the device manufacturer. A device running Android 4.3 or higher <em>may

  not support</em> the OpenGL ES 3.0 API. For information on checking what version of OpenGL ES

  is supported at run time, see <a href="#version-check">Checking OpenGL ES Version</a>.

</p>

<p class="note"><strong>Note:</strong>

  The specific API provided by the Android framework is similar to the J2ME JSR239 OpenGL ES API,

  but is not identical. If you are familiar with J2ME JSR239 specification, be alert for

  variations.</p>

<p class="note"><b>Note:</b> The specific API provided by the Android framework is similar to the

  J2ME JSR239 OpenGL ES  API, but is not identical. If you are familiar with J2ME JSR239

  specification, be alert for variations.</p>

<h2 id="basics">The Basics</h2>

    <a href="{@docRoot}training/graphics/opengl/touch.html">Responding to Touch Events</a>.</dd>

  <dt><strong>{@link android.opengl.GLSurfaceView.Renderer}</strong></dt>

  <dd>This interface defines the methods required for drawing graphics in an OpenGL {@link

  <dd>This interface defines the methods required for drawing graphics in a {@link

    android.opengl.GLSurfaceView}. You must provide an implementation of this interface as a

    separate class and attach it to your {@link android.opengl.GLSurfaceView} instance using

    {@link android.opengl.GLSurfaceView#setRenderer(android.opengl.GLSurfaceView.Renderer)

    </dd>

</dl>

<h3 id="packages">OpenGL packages</h3>

<p>Once you have established a container view for OpenGL using {@link

<h3 id="packages">OpenGL ES packages</h3>

<p>Once you have established a container view for OpenGL ES using {@link

android.opengl.GLSurfaceView} and {@link android.opengl.GLSurfaceView.Renderer}, you can begin

calling OpenGL APIs using the following classes:</p>

  <li>OpenGL ES 1.0/1.1 API Packages

    <ul>

      <li>{@link android.opengl} - This package provides a static interface to the OpenGL ES

1.0/1.1 classes and better performance than the javax.microedition.khronos package interfaces.

        1.0/1.1 classes and better performance than the {@code javax.microedition.khronos} package

        interfaces.

        <ul>

          <li>{@link android.opengl.GLES10}</li>

          <li>{@link android.opengl.GLES10Ext}</li>

  <li>OpenGL ES 2.0 API Class

    <ul>

      <li>{@link android.opengl.GLES20 android.opengl.GLES20} - This package provides the

interface to OpenGL ES 2.0 and is available starting with Android 2.2 (API Level 8).</li>

        interface to OpenGL ES 2.0 and is available starting with Android 2.2 (API level 8).</li>

    </ul>

  </li>

  <li>OpenGL ES 3.0 API Class

    <ul>

      <li>{@link android.opengl.GLES30 android.opengl.GLES30} - This package provides the

        interface to OpenGL ES 3.0 and is available starting with Android 4.3 (API level 18).</li>

    </ul>

  </li>

</ul>

<p>If you'd like to start building an app with OpenGL right away, follow the

<a href="{@docRoot}training/graphics/opengl/index.html">Displaying Graphics with OpenGL ES</a> class.

<p>If you want to start building an app with OpenGL ES right away, follow the

<a href="{@docRoot}training/graphics/opengl/index.html">Displaying Graphics with OpenGL ES</a>

class.

</p>

<h2 id="manifest">Declaring OpenGL Requirements</h2>

<p>If your application uses OpenGL features that are not available on all devices, you must include

these requirements in your <a

href="{@docRoot}guide/topics/manifest/manifest-intro.html">AndroidManifest.xml</a></code> file.

href="{@docRoot}guide/topics/manifest/manifest-intro.html">AndroidManifest.xml</a> file.

Here are the most common OpenGL manifest declarations:</p>

<ul>

</pre>

    <p>Adding this declaration causes Google Play to restrict your application from being

  installed on devices that do not support OpenGL ES 2.0.</p>

    installed on devices that do not support OpenGL ES 2.0. If your application is exclusively for

    devices that support OpenGL ES 3.0, you can also specify this in your manifest:</p>

<pre>

<!-- Tell the system this app requires OpenGL ES 3.0. -->

<uses-feature android:glEsVersion="0x00030000" android:required="true" />

</pre>

    <p class="note"><strong>Note:</strong>

      The OpenGL ES 3.0 API is backwards-compatible with the 2.0 API, which means you can be more

      flexible with your implementation of OpenGL ES in your application. By declaring the OpenGL

      ES 2.0 API as a requirement in your manifest, you can use that API version as a default, check

      for the availability of the 3.0 API at run time and then use OpenGL ES 3.0 features if the

      device supports it. For more information about checking the OpenGL ES version supported by a

      device, see <a href="#version-check">Checking OpenGL ES Version</a>.

    </p>

  </li>

  <li><strong>Texture compression requirements</strong> - If your application uses texture

compression formats, you must declare the formats your application supports in your manifest file

coordinates of your graphics so that they map correctly to Android device screens. The camera view

matrix creates a transformation that renders objects from a specific eye position.</p>

<h3 id="proj-es1">Projection and camera view in OpenGL ES 1.0</h3>

<p>In the ES 1.0 API, you apply projection and camera view by creating each matrix and then

adding them to the OpenGL environment.</p>

</ol>

<h3 id="proj-es2">Projection and camera view in OpenGL ES 2.0</h3>

<p>In the ES 2.0 API, you apply projection and camera view by first adding a matrix member to

the vertex shaders of your graphics objects. With this matrix member added, you can then

<h3 id="proj-es2">Projection and camera view in OpenGL ES 2.0 and higher</h3>

<p>In the ES 2.0 and 3.0 APIs, you apply projection and camera view by first adding a matrix member

to the vertex shaders of your graphics objects. With this matrix member added, you can then

generate and apply projection and camera viewing matrices to your objects.</p>

<ol>

</li>

<li><strong>Create projection and camera viewing matrices</strong> - Generate the projection and

viewing matrices to be applied the graphic objects. The following example code shows how to modify

the {@link

android.opengl.GLSurfaceView.Renderer#onSurfaceCreated(javax.microedition.khronos.opengles.GL10,

javax.microedition.khronos.egl.EGLConfig) onSurfaceCreated()} and {@link

android.opengl.GLSurfaceView.Renderer#onSurfaceChanged(javax.microedition.khronos.opengles.GL10,

int, int) onSurfaceChanged()} methods of a {@link android.opengl.GLSurfaceView.Renderer}

implementation to create camera view matrix and a projection matrix based on the screen aspect ratio

of the device.

the {@link android.opengl.GLSurfaceView.Renderer#onSurfaceCreated onSurfaceCreated()} and

{@link android.opengl.GLSurfaceView.Renderer#onSurfaceChanged onSurfaceChanged()} methods of a

{@link android.opengl.GLSurfaceView.Renderer} implementation to create camera view matrix and a

projection matrix based on the screen aspect ratio of the device.

<pre>

public void onSurfaceCreated(GL10 unused, EGLConfig config) {

<p>For a complete example of how to apply projection and camera view with OpenGL ES 2.0, see the <a

href="{@docRoot}training/graphics/opengl/index.html">Displaying Graphics with OpenGL ES</a> class.</p>

<h2 id="faces-winding">Shape Faces and Winding</h2>

<p>In OpenGL, the face of a shape is a surface defined by three or more points in three-dimensional

clockwise face as the front face, but doing so requires more code and is likely to confuse

experienced OpenGL developers when you ask them for help. So don’t do that.</p>

<h2 id="compatibility">OpenGL Versions and Device Compatibility</h2>

<p>The OpenGL ES 1.0 and 1.1 API specifications have been supported since Android 1.0.

Beginning with Android 2.2 (API Level 8), the framework supports the OpenGL ES 2.0 API

Beginning with Android 2.2 (API level 8), the framework supports the OpenGL ES 2.0 API

specification. OpenGL ES 2.0 is supported by most Android devices and is recommended for new

applications being developed with OpenGL. For information about the relative number of

Android-powered devices that support a given version of OpenGL ES, see the <a

href="{@docRoot}resources/dashboard/opengl.html">OpenGL ES Versions Dashboard</a>.</p>

applications being developed with OpenGL. OpenGL ES 3.0 is supported with Android 4.3

(API level 18) and higher, on devices that provide an implementation of the OpenGL ES 3.0 API.

For information about the relative number of Android-powered devices

that support a given version of OpenGL ES, see the

<a href="{@docRoot}about/dashboards/index.html#OpenGL">OpenGL ES Version Dashboard</a>.</p>

<p>Graphics programming with OpenGL ES 1.0/1.1 API is significantly different than using the 2.0

and higher versions. The 1.x version of the API has more convenience methods and a fixed graphics

pipeline, while the OpenGL ES 2.0 and 3.0 APIs provide more direct control of the pipeline through

use of OpenGL shaders. You should carefully consider the graphics requirements and choose the API

version that works best for your application. For more information, see

<a href="#choosing-version">Choosing an OpenGL API Version</a>.</p>

<p>The OpenGL ES 3.0 API provides additional features and better performance than the 2.0 API and is

also backward compatible. This means that you can potentially write your application targeting

OpenGL ES 2.0 and conditionally include OpenGL ES 3.0 graphics features if they are available. For

more information on checking for availability of the 3.0 API, see

<a href="#version-check">Checking OpenGL ES Version</a></p>

<h3 id="textures">Texture compression support</h3>

<p>Texture compression can significantly increase the performance of your OpenGL application by

reducing memory requirements and making more efficient use of memory bandwidth. The Android

framework provides support for the ETC1 compression format as a standard feature, including a {@link

android.opengl.ETC1Util} utility class and the {@code etc1tool} compression tool (located in the

Android SDK at {@code <sdk>/tools/}). For an example of an Android application that uses

texture compression, see the <a

href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/graphics/CompressedTextureActivity.html"

>CompressedTextureActivity</a> code sample.</p>

texture compression, see the {@code CompressedTextureActivity} code sample in Android SDK

({@code &lt;sdk&gt;/samples/&lt;version&gt;/ApiDemos/src/com/example/android/apis/graphics/}).</p>

<p>The ETC format is supported by most Android devices, but it not guarranteed to be available. To

check if the ETC1 format is supported on a device, call the {@link

android.opengl.ETC1Util#isETC1Supported() ETC1Util.isETC1Supported()} method.</p>

<p class="caution"><strong>Caution:</strong> The ETC1 format is supported by most Android devices,

but it not guaranteed to be available. To check if the ETC1 format is supported on a device, call

the {@link android.opengl.ETC1Util#isETC1Supported() ETC1Util.isETC1Supported()} method.</p>

<p class="note"><b>Note:</b> The ETC1 texture compression format does not support textures with an

alpha channel. If your application requires textures with an alpha channel, you should

transparency (alpha channel). If your application requires textures with transparency, you should

investigate other texture compression formats available on your target devices.</p>

<p>Beyond the ETC1 format, Android devices have varied support for texture compression based on

<p>The ETC2/EAC texture compression formats are guaranteed to be available when using the OpenGL ES

3.0 API. This texture format offers excellent compression ratios with high visual quality and the

format also supports transparency (alpha channel).</p>

<p>Beyond the ETC formats, Android devices have varied support for texture compression based on

their GPU chipsets and OpenGL implementations. You should investigate texture compression support on

the devices you are are targeting to determine what compression types your application should

support. In order to determine what texture formats are supported on a given device, you must <a

    </ul>

  </li>

  <li><strong>3DC</strong> - 3DC texture compression (3DC) is a less widely available format that

supports RGB textures with an an alpha channel. This format is represented by the following OpenGL

extension name:</li>

supports RGB textures with an alpha channel. This format is represented by the following OpenGL

extension name:

    <ul>

      <li>{@code GL_AMD_compressed_3DC_texture}</li>

    </ul>

  </li>

</ul>

<p class="warning"><strong>Warning:</strong> These texture compression formats are <em>not

<a

href="{@docRoot}guide/topics/graphics/opengl.html#manifest">OpenGL manifest declarations</a>.</p>

<h3 id="gl-extension-query">Determining OpenGL extensions</h3>

<p>Implementations of OpenGL vary by Android device in terms of the extensions to the OpenGL ES API

that are supported. These extensions include texture compressions, but typically also include other

  <li>Run the following code on your target devices to determine what texture compression

formats are supported:

<pre>

  String extensions = javax.microedition.khronos.opengles.GL10.glGetString(GL10.GL_EXTENSIONS);

String extensions = javax.microedition.khronos.opengles.GL10.glGetString(

        GL10.GL_EXTENSIONS);

</pre>

  <p class="warning"><b>Warning:</b> The results of this call <em>vary by device!</em> You

  <p class="warning"><b>Warning:</b> The results of this call <em>vary by device model!</em> You

must run this call on several target devices to determine what compression types are commonly

supported.</p>

  </li>

</ol>

<h3 id="version-check">Checking OpenGL ES Version</h3>

<p>There are several versions of the OpenGL ES available on Android devices. You can specify the

minimum version of the API your application requires in your <a href="#manifest">manifest</a>, but

you may also want to take advantage of features in a newer API at the same time. For example,

the OpenGL ES 3.0 API is backward-compatible with the 2.0 version of the API, so you may want to

write your application so that it uses OpenGL ES 3.0 features, but falls back to the 2.0 API if the

3.0 API is not available.</p>

<p>Before using OpenGL ES features from a version higher than the minimum required in your

application manifest, your application should check the version of the API available on the device.

You can do this in one of two ways:</p>

<ol>

  <li>Attempt create the higher-level OpenGL ES context ({@link android.opengl.EGLContext}) and

    check the result.</li>

  <li>Create a minimum-supported OpenGL ES context and check the version value.</li>

</ol>

<p>The following example code demonstrates how to check the available OpenGL ES version by creating

an {@link android.opengl.EGLContext} and checking the result. This example shows how to check for

OpenGL ES 3.0 version:</p>

<pre>

private static double glVersion = 3.0;

private static class ContextFactory implements GLSurfaceView.EGLContextFactory {

  private static int EGL_CONTEXT_CLIENT_VERSION = 0x3098;

  public EGLContext createContext(

          EGL10 egl, EGLDisplay display, EGLConfig eglConfig) {

      Log.w(TAG, "creating OpenGL ES " + glVersion + " context");

      int[] attrib_list = {EGL_CONTEXT_CLIENT_VERSION, (int) glVersion,

              EGL10.EGL_NONE };

      // attempt to create a OpenGL ES 3.0 context

      EGLContext context = egl.eglCreateContext(

              display, eglConfig, EGL10.EGL_NO_CONTEXT, attrib_list);

      return context; // returns null if 3.0 is not supported;

  }

}

</pre>

<p>If the {@code createContext()} method show above returns null, your code should create a OpenGL

ES 2.0 context instead and fall back to using only that API.</p>

<p>The following code example demonstrates how to check the OpenGL ES version by creating a minimum

supported context first, and then checking the version string:</p>

<pre>

// Create a minimum supported OpenGL ES context, then check:

String version = javax.microedition.khronos.opengles.GL10.glGetString(

        GL10.GL_VERSION);

Log.w(TAG, "Version: " + version );

// The version format is displayed as: "OpenGL ES <major>.<minor>"

// followed by optional content provided by the implementation.

</pre>

<p>With this approach, if you discover that the device supports a higher-level API version, you

must destroy the minimum OpenGL ES context and create a new context with the higher

available API version.</p>

<h2 id="choosing-version">Choosing an OpenGL API Version</h2>

<p>OpenGL ES API version 1.0 (and the 1.1 extensions) and version 2.0 both provide high

<p>OpenGL ES 1.0 API version (and the 1.1 extensions), version 2.0, and version 3.0 all provide high

performance graphics interfaces for creating 3D games, visualizations and user interfaces. Graphics

programming for the OpenGL ES 1.0/1.1 API versus ES 2.0 differs significantly, and so developers

should carefully consider the following factors before starting development with either API:</p>

progamming for OpenGL ES 2.0 and 3.0 is largely similar, with version 3.0 representing a superset

of the 2.0 API with additional features. Programming for the OpenGL ES 1.0/1.1 API versus OpenGL ES

2.0 and 3.0 differs significantly, and so developers should carefully consider the following

factors before starting development with these APIs:</p>

<ul>

  <li><strong>Performance</strong> - In general, OpenGL ES 2.0 provides faster graphics performance

than the ES 1.0/1.1 APIs. However, the performance difference can vary depending on the Android

device your OpenGL application is running on, due to differences in the implementation of the OpenGL

graphics pipeline.</li>

  <li><strong>Performance</strong> - In general, OpenGL ES 2.0 and 3.0 provide faster graphics

    performance than the ES 1.0/1.1 APIs. However, the performance difference can vary depending on

    the Android device your OpenGL application is running on, due to differences in hardware

    manufacturer's implementation of the OpenGL ES graphics pipeline.</li>

  <li><strong>Device Compatibility</strong> - Developers should consider the types of devices,

    Android versions and the OpenGL ES versions available to their customers. For more information

on OpenGL compatibility across devices, see the <a href="#compatibility">OpenGL Versions and Device

Compatibility</a> section.</li>

    on OpenGL compatibility across devices, see the <a href="#compatibility">OpenGL Versions and

    Device Compatibility</a> section.</li>

  <li><strong>Coding Convenience</strong> - The OpenGL ES 1.0/1.1 API provides a fixed function

pipeline and convenience functions which are not available in the ES 2.0 API. Developers who are new

to OpenGL may find coding for OpenGL ES 1.0/1.1 faster and more convenient.</li>

  <li><strong>Graphics Control</strong> - The OpenGL ES 2.0 API provides a higher degree

    pipeline and convenience functions which are not available in the OpenGL ES 2.0 or 3.0 APIs.

    Developers who are new to OpenGL ES may find coding for version 1.0/1.1 faster and more

    convenient.</li>

  <li><strong>Graphics Control</strong> - The OpenGL ES 2.0 and 3.0 APIs provide a higher degree

    of control by providing a fully programmable pipeline through the use of shaders. With more

    direct control of the graphics processing pipeline, developers can create effects that would be

    very difficult to generate using the 1.0/1.1 API.</li>

  <li><strong>Texture Support</strong> - The OpenGL ES 3.0 API has the best support for texture

    compression because it guarantees availability of the ETC2 compression format, which supports

    transparency. The 1.x and 2.0 API implementations usually include support for ETC1, however

    this texture format does not support transparency and so you must typically provide resources

    in other compression formats supported by the devices you are targeting. For more information,

    see <a href="#textures">Texture compression support</a>.</li>

</ul>

<p>While performance, compatibility, convenience, control and other factors may influence your

decision, you should pick an OpenGL API version based on what you think provides the best experience

for your users.</p>