From a638474a479d04ddb164d8e2751d8379628c3e2c Mon Sep 17 00:00:00 2001 From: Joe Fernandez Date: Thu, 7 Jul 2011 15:22:09 -0700 Subject: Revert "docs: OpenGL Tutorials" This reverts commit 4cd8360943a167505c929a309cccd7cb56eb4138 --- docs/html/images/opengl/coordinates.png | Bin 14019 -> 0 bytes docs/html/images/opengl/helloopengl-es10-1.png | Bin 24165 -> 0 bytes docs/html/images/opengl/helloopengl-es10-2.png | Bin 21871 -> 0 bytes docs/html/images/opengl/helloopengl-es20-1.png | Bin 20134 -> 0 bytes docs/html/images/opengl/helloopengl-es20-2.png | Bin 20072 -> 0 bytes docs/html/resources/resources-data.js | 20 - .../html/resources/tutorials/opengl/opengl-es10.jd | 409 ---------------- .../html/resources/tutorials/opengl/opengl-es20.jd | 514 --------------------- 8 files changed, 943 deletions(-) delete mode 100644 docs/html/images/opengl/coordinates.png delete mode 100644 docs/html/images/opengl/helloopengl-es10-1.png delete mode 100644 docs/html/images/opengl/helloopengl-es10-2.png delete mode 100644 docs/html/images/opengl/helloopengl-es20-1.png delete mode 100644 docs/html/images/opengl/helloopengl-es20-2.png delete mode 100644 docs/html/resources/tutorials/opengl/opengl-es10.jd delete mode 100644 docs/html/resources/tutorials/opengl/opengl-es20.jd diff --git a/docs/html/images/opengl/coordinates.png b/docs/html/images/opengl/coordinates.png deleted file mode 100644 index 7180cd5..0000000 Binary files a/docs/html/images/opengl/coordinates.png and /dev/null differ diff --git a/docs/html/images/opengl/helloopengl-es10-1.png b/docs/html/images/opengl/helloopengl-es10-1.png deleted file mode 100644 index bdfbcdb..0000000 Binary files a/docs/html/images/opengl/helloopengl-es10-1.png and /dev/null differ diff --git a/docs/html/images/opengl/helloopengl-es10-2.png b/docs/html/images/opengl/helloopengl-es10-2.png deleted file mode 100644 index c07dabb..0000000 Binary files a/docs/html/images/opengl/helloopengl-es10-2.png and /dev/null differ diff --git a/docs/html/images/opengl/helloopengl-es20-1.png b/docs/html/images/opengl/helloopengl-es20-1.png deleted file mode 100644 index 44abe77..0000000 Binary files a/docs/html/images/opengl/helloopengl-es20-1.png and /dev/null differ diff --git a/docs/html/images/opengl/helloopengl-es20-2.png b/docs/html/images/opengl/helloopengl-es20-2.png deleted file mode 100644 index 22fa52c..0000000 Binary files a/docs/html/images/opengl/helloopengl-es20-2.png and /dev/null differ diff --git a/docs/html/resources/resources-data.js b/docs/html/resources/resources-data.js index f71307e..097d004 100644 --- a/docs/html/resources/resources-data.js +++ b/docs/html/resources/resources-data.js @@ -762,26 +762,6 @@ var ANDROID_RESOURCES = [ } }, { - tags: ['tutorial', 'gl', 'new'], - path: 'tutorials/opengl/opengl-es10.html', - title: { - en: 'Hello OpenGL ES 1.0' - }, - description: { - en: 'The basics of implementing an application using the OpenGL ES 1.0 APIs.' - } - }, - { - tags: ['tutorial', 'gl', 'new'], - path: 'tutorials/opengl/opengl-es20.html', - title: { - en: 'Hello OpenGL ES 2.0' - }, - description: { - en: 'The basics of implementing an application using the OpenGL ES 2.0 APIs.' - } - }, - { tags: ['tutorial', 'testing'], path: 'tutorials/testing/helloandroid_test.html', title: { diff --git a/docs/html/resources/tutorials/opengl/opengl-es10.jd b/docs/html/resources/tutorials/opengl/opengl-es10.jd deleted file mode 100644 index d18a547..0000000 --- a/docs/html/resources/tutorials/opengl/opengl-es10.jd +++ /dev/null @@ -1,409 +0,0 @@ -page.title=Hello OpenGL ES 1.0 -parent.title=Tutorials -parent.link=../../browser.html?tag=tutorial -@jd:body - - -
- -
- -

This tutorial shows you how to create a simple Android application that uses OpenGL ES 1.0 and -perform some basic operations using the OpenGL ES 1.0 API, including:

- - - -

This tutorial demonstrates use of the OpenGL ES 1.0 API. Both the OpenGL ES 1.0 and the ES 1.1 -API are supported by the Android framework since release 1.0 (API Level 1). The OpenGL ES 1.1 API -is an extention of the 1.0 API, and it's capabilities are beyond the scope of this tutorial.

- -

Beginning with Android 2.2 (API Level 8), the framework supports OpenGL ES 2.0. For more -information about compatibility for OpenGL versions and Android devices, see the 3D with OpenGL document.

- - -

Creating an OpenGL ES 1.0 Application

- -

OpenGL applications for Android have the same basic structure as other applications, however -OpenGL applications use {@link android.opengl.GLSurfaceView} where other, non-OpenGL -applications use the {@link android.view.View} or {@link android.view.SurfaceView} class.

- -

To get started using OpenGL in your Android application, you must implement both a {@link -android.opengl.GLSurfaceView} and a {@link android.opengl.GLSurfaceView.Renderer}. The {@link -android.opengl.GLSurfaceView} is the main view type for the OpenGL applications and the {@link -android.opengl.GLSurfaceView.Renderer} controls what is drawn within that view. For more -information about these classes, see the 3D -with OpenGL document.

- -

To create an application that uses OpenGL ES 1.0:

- -
    -
  1. Start a new Android project with an Activity called HelloOpenGLES10. - -

    Note: If you have not created a basic Android application yet, follow the - Hello World Tutorial instructions - to familiarize yourself with the process.

    -
    2. - -
  2. Modify the HelloOpenGLES10 class as follows: -
    -package com.example.android.apis.graphics;
-
-import android.app.Activity;
-import android.content.Context;
-import android.opengl.GLSurfaceView;
-import android.os.Bundle;
-
-public class HelloOpenGLES10 extends Activity {
-  
-    private GLSurfaceView mGLView;    
-  
-    @Override
-    public void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        
-        mGLView = new HelloOpenGLSurfaceView(this);
-        setContentView(mGLView);
-    }
-    
-    @Override
-    protected void onPause() {
-        super.onPause();
-        mGLView.onPause();
-    }
-    
-    @Override
-    protected void onResume() {
-        super.onResume();
-        mGLView.onResume();
-    }
-    
-}
-  
-class HelloOpenGLES10SurfaceView extends GLSurfaceView {
-
-    public HelloOpenGLES10SurfaceView(Context context){
-        super(context);
-        setRenderer(new HelloOpenGLES10Renderer());
-    }
-
-}
-
    -

    This Activity class creates a basic container for a {@link android.opengl.GLSurfaceView}.

    -
    3. - -
  3. Create the following class HelloOpenGLES10Renderer, which implements the - {@link android.opengl.GLSurfaceView.Renderer} interface: - -
    -package com.example.android.apis.graphics;
-
-import javax.microedition.khronos.egl.EGLConfig;
-import javax.microedition.khronos.opengles.GL10;
-
-import android.opengl.GLSurfaceView;
-
-public class HelloOpenGLES10Renderer implements GLSurfaceView.Renderer {
-
-    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
-        // Set the background frame color
-        gl.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
-    }
-    
-    public void onDrawFrame(GL10 gl) {
-        // Redraw background color
-        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
-    }
-    
-    public void onSurfaceChanged(GL10 gl, int width, int height) {
-        gl.glViewport(0, 0, width, height);
-    }
-  
-}
-
    -
    4. -
- -

These classes create a simple Android application which displays a grey screen using OpenGL -ES 1.0 calls. While this application does not do anything very interesting, by creating these two -classes, you have layed the foundation needed to start drawing graphic elements with OpenGL ES -1.0.

- -

If you are familiar with the OpenGL ES APIs, these two classes should give you enough information -to start using the OpenGL ES 1.0 API and creating graphics. However, if you need a bit more help -getting started with OpenGL, head on to the next sections for a few more tips.

- -

Drawing Graphic Elements

- -

Once you have implemented a {@link android.opengl.GLSurfaceView.Renderer}, the next step is to -draw something on it. This section shows you how to define and draw a basic triangle shape with the -Android OpenGL ES 1.0 API.

- -

Note: The following instructions build on the previous section, so if you -have not been following along, go back to the previous section and catch -up.

- -

Defining a Triangle

- -

OpenGL allows you to define objects using coordinates in three-dimensional space. So, before you - can draw a triangle, you must define its coordinates. In OpenGL, the typical way to do this is to - define a vertex array for the coordinates.

- -

By default, OpenGL ES assumes a coordinate system where 0,0,0 (X,Y,Z) specifies the center of - the {@link android.opengl.GLSurfaceView} frame, 1,1,0 is the top right corner of the frame and --1,-1,0 is bottom left corner of the frame.

- -

To define a vertex array for a triangle:

- -
    -
  1. In your HelloOpenGLES10Renderer class, add new member variable to contain the -vertices of a triangle shape: -
    -    private FloatBuffer triangleVB;
-
    -
    2. - -
  2. Create a method, initShapes() which populates this member variable: -
    -    private void initShapes(){
-    
-        float triangleCoords[] = {
-            // X, Y, Z
-            -0.5f, -0.25f, 0,
-             0.5f, -0.25f, 0,
-             0.0f,  0.559016994f, 0
-        }; 
-        
-        // initialize vertex Buffer for triangle  
-        ByteBuffer vbb = ByteBuffer.allocateDirect(
-                // (# of coordinate values * 4 bytes per float)
-                triangleCoords.length * 4); 
-        vbb.order(ByteOrder.nativeOrder());
-        triangleVB = vbb.asFloatBuffer();
-        triangleVB.put(triangleCoords);
-        triangleVB.position(0);
-    
-    }
-
    -

    This method defines a two-dimensional triangle shape with three equal sides.

    -
    3. -
  3. Modify your onSurfaceCreated() method to initialize your triangle: - 
    -    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
-    
-        // Set the background frame color
-        gl.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
-        
-        // initialize the triangle vertex array
-        initShapes();
-    }
-
    -

    Warning: Shapes and other static objects should be initialized - once in your onSurfaceCreated() method for best performance. Avoid initializing the - new objects in onDrawFrame(), as this causes the system to re-create the objects - for every frame redraw and slows down your application. -

    -
    4. - -
- -

Draw the Triangle

- -

Now that you have defined a shape to draw, you can use the OpenGL APIs to draw the -object.

- -

To draw the triangle with OpenGL:

- -
    -
  1. Before you can draw your triangle, you must tell OpenGL that you are using vertex arrays. - Modify your onSurfaceCreated() method to enable vertex arrays. -
    -    public void onSurfaceCreated(GL10 gl, EGLConfig config) {
-    
-        // Set the background frame color
-        gl.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
-        
-        // initialize the triangle vertex array
-        initShapes();
-        
-        // Enable use of vertex arrays
-        gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
-    }
-
    -

    At this point, you are ready to draw the triangle object in the OpenGL frame.

    -
    2. - -
  2. Modify your onDrawFrame() method to draw the triangle. -
    -    public void onDrawFrame(GL10 gl) {
-        // Redraw background color
-        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
-    
-        // Draw the triangle
-        gl.glColor4f(0.63671875f, 0.76953125f, 0.22265625f, 0.0f);
-        gl.glVertexPointer(3, GL10.GL_FLOAT, 0, triangleVB);
-        gl.glDrawArrays(GL10.GL_TRIANGLES, 0, 3);
-    }
-
    -

    Note: Since the triangle is stationary at this point, the system is redrawing the - object repeatedly in exactly the same place and so is not the most efficient use of the OpenGL - graphics pipeline. In a later section, we add motion to the object to - justify this use of processing power.

    -
    3. -
- -

Try running this example application on your emulator or test device and -you should see something like this:

- - - -

There are a few problems with this example. First of all, it's not going to impress your -friends. Secondly, the triangle is a bit squashed and changes shape when you change the screen -orientation of the test device. The reason the shape is skewed is due to the fact that the object is -being rendered in a frame which is not perfectly square. We fix that problem in the -next section.

- -

Using Projection and Views

- -

OpenGL Projection and Views provide a way to calculate the coordinates of graphic objects in -realistic proportions on graphics displays of any size. One of the basic problems in displaying -graphics is that Android device displays are typically not square and—by default—OpenGL -happily maps a perfectly square, uniform coordinate system onto your typically non-square -screen.

- - - -

The illustration above shows the uniform coordinate system assumed for an OpenGL frame on the - left, and how these coordinates actually map to a typical device screen in landscape orientation - on the right. To solve this problem, you can apply OpenGL projection modes and views to transform - object coordinates so your graphic objects have the correct proportions on any display.

- -

To use a projection transformation on your triangle:

-
    -
  1. Modify your onSurfaceChanged() method to enable {@link - javax.microedition.khronos.opengles.GL10#GL_PROJECTION GL10.GL_PROJECTION} mode, calculate the - screen ratio and apply the ratio as a transformation of the object coordinates. -
    -  public void onSurfaceChanged(GL10 gl, int width, int height) {
-      gl.glViewport(0, 0, width, height);
-      
-      // make adjustments for screen ratio
-      float ratio = (float) width / height;
-      gl.glMatrixMode(GL10.GL_PROJECTION);
-      gl.glLoadIdentity();
-      gl.glFrustumf(-ratio, ratio, -1, 1, 3, 7);
-  }  
-
    -
    2. - -
  2. Next, modify your onDrawFrame() method to apply the {@link -javax.microedition.khronos.opengles.GL10#GL_MODELVIEW GL_MODELVIEW} mode and set -a view point for the display using {@link -android.opengl.GLU#gluLookAt(javax.microedition.khronos.opengles.GL10, float, float, float, float, -float, float, float, float, float) GLU#gluLookAt()}. -
    -    public void onDrawFrame(GL10 gl) {
-        // Redraw background color
-        gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
-        
-        // Set GL_MODELVIEW transformation mode
-        gl.glMatrixMode(GL10.GL_MODELVIEW);
-        gl.glLoadIdentity();
-        
-        // When using GL_MODELVIEW, you must set the view point
-        GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);        
-        
-        // Draw the triangle
-        ...
-    }
-
    -
    3. -
- -

Try running this updated application on your emulator or test device and you should see something -like this:

- - - -

Now that you have applied this transformation, the triangle has three equal sides, instead of the -squashed display in the earlier version.

- -

Adding Motion

- -

While it may be interesting exercise to create static graphic objects with OpenGL ES, chances -are you want at least some of your objects to move. In this section, we add motion to to our -triangle by rotating it.

- -

To add rotation to your triangle:

- - -

Run the application with this code and your triangle should rotate around its center.

- - - -

Additional Resources

- -

Be sure to check out the OpenGL ES code samples are available in the -API -Demos sample application and listed in Related Samples -sidebar above. -

diff --git a/docs/html/resources/tutorials/opengl/opengl-es20.jd b/docs/html/resources/tutorials/opengl/opengl-es20.jd deleted file mode 100644 index 5cdc343..0000000 --- a/docs/html/resources/tutorials/opengl/opengl-es20.jd +++ /dev/null @@ -1,514 +0,0 @@ -page.title=Hello OpenGL ES 1.0 -parent.title=Tutorials -parent.link=../../browser.html?tag=tutorial -@jd:body - - -
- -
- -

This tutorial shows you how to create a simple Android application that uses OpenGL ES 2.0 and -perform some basic operations using the OpenGL ES 2.0 API, including:

- - - -

This tutorial demonstrates use of the OpenGL ES 2.0 API. Beginning with Android 2.2 (API Level -8), the framework supports OpenGL ES 2.0.

- -

Both the OpenGL ES 1.0 and the ES 1.1 API are supported by the Android framework since release -1.0 (API Level 1).For more information about compatibility for OpenGL versions and Android devices, -see the 3D with OpenGL -document.

- - -

Creating an OpenGL ES 1.0 Application

- -

OpenGL applications for Android have the same basic structure as other applications, however -OpenGL applications use {@link android.opengl.GLSurfaceView} where other, non-OpenGL -applications use the {@link android.view.View} or {@link android.view.SurfaceView} class.

- -

To get started using OpenGL in your Android application, you must implement both a {@link -android.opengl.GLSurfaceView} and a {@link android.opengl.GLSurfaceView.Renderer}. The {@link -android.opengl.GLSurfaceView} is the main view type for the OpenGL applications and the {@link -android.opengl.GLSurfaceView.Renderer} controls what is drawn within that view. For more -information about these classes, see the 3D -with OpenGL document.

- -

To create an application that uses OpenGL ES 2.0:

- -
    -
  1. Start a new Android project with an Activity called HelloOpenGLES20. - -

    Note: If you have not created a basic Android application yet, follow the - Hello World Tutorial instructions - to familiarize yourself with the process.

    -
    2. - -
  2. Modify the HelloOpenGLES20 class as follows: -
    -package com.example.android.apis.graphics;
-
-import android.app.Activity;
-import android.content.Context;
-import android.opengl.GLSurfaceView;
-import android.os.Bundle;
-
-public class HelloOpenGLES20 extends Activity {
-  
-    private GLSurfaceView mGLView;    
-  
-    @Override
-    public void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        
-        mGLView = new HelloOpenGLES20SurfaceView(this);
-        setContentView(mGLView);
-    }
-    
-    @Override
-    protected void onPause() {
-        super.onPause();
-        mGLView.onPause();
-    }
-    
-    @Override
-    protected void onResume() {
-        super.onResume();
-        mGLView.onResume();
-    }
-}
-  
-class HelloOpenGLES20SurfaceView extends GLSurfaceView {
-
-    public HelloOpenGLES20SurfaceView(Context context){
-        super(context);
-        
-        // Create an OpenGL ES 2.0 context.
-        setEGLContextClientVersion(2);
-
-        setRenderer(new HelloOpenGLES20Renderer());
-    }
-}
-
    -

    This Activity class creates a basic container for a {@link android.opengl.GLSurfaceView}.

    -
    3. - -
  3. Create the following class HelloOpenGLES20Renderer, which implements the - {@link android.opengl.GLSurfaceView.Renderer} interface: - -
    -package com.example.android.apis.graphics;
-
-import javax.microedition.khronos.egl.EGLConfig;
-import javax.microedition.khronos.opengles.GL10;
-
-import android.opengl.GLES20;
-import android.opengl.GLSurfaceView;
-
-public class HelloOpenGLES20Renderer implements GLSurfaceView.Renderer {
-  
-    public void onSurfaceCreated(GL10 unused, EGLConfig config) {
-    
-        // Set the background frame color
-        GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
-    }
-    
-    public void onDrawFrame(GL10 unused) {
-    
-        // Redraw background color
-        GLES20.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
-    }
-    
-    public void onSurfaceChanged(GL10 unused, int width, int height) {
-        GLES20.glViewport(0, 0, width, height);
-    }
-  
-}
-
    -
    4. -
- -

These classes create a simple Android application which displays a grey screen using OpenGL -ES 2.0 calls. While this application does not do anything very interesting, by creating these two -classes, you have layed the foundation needed to start drawing graphic elements with OpenGL ES -2.0.

- -

If your application only supports OpenGL ES 2.0, then you should declare that your application - requires OpenGL ES 2.0 by adding the following settings to your AndroidManifest.xml file as -shown below.

- -
-...
-    </application>
-    
-    <!-- Tell the system that you need ES 2.0. -->
-    <uses-feature android:glEsVersion="0x00020000" android:required="true" />
-
-</manifest>
-
- -

Adding this declaration hides your application from devices that do not support OpenGL ES 2.0 -in the Android Market.

- -

If you are familiar with the OpenGL ES APIs, these preceding classes and the AndroidManifest.xml -declaration should give you enough information to start using the OpenGL ES API and creating -graphics. However, if you need a bit more help getting started with OpenGL, head on to the next -sections for a few more tips.

- - -

Drawing Graphic Elements

- -

Once you have implemented a {@link android.opengl.GLSurfaceView.Renderer}, the next step is to -draw something on it. This section shows you how to define and draw a basic triangle shape with the -OpenGL ES 2.0 API.

- -

Note: The following instructions build on the previous section, so if you -have not been following along, go back to the previous section and catch -up.

- -

Defining a Triangle

- -

OpenGL allows you to define objects using coordinates in three-dimensional space. So, before you - can draw a triangle, you must define its coordinates. In OpenGL, the typical way to do this is to - define a vertex array for the coordinates.

- -

By default, OpenGL ES assumes a coordinate system where 0,0,0 (X,Y,Z) specifies the center of - the {@link android.opengl.GLSurfaceView} frame, 1,1,0 is the top right corner of the frame and --1,-1,0 is bottom left corner of the frame.

- -

To define a vertex array for a triangle:

- -
    -
  1. In your HelloOpenGLES20Renderer class, add new member variable to contain the -vertices of a triangle shape: -
    -    private FloatBuffer triangleVB;
-
    -
    2. - -
  2. Create a method, initShapes() which populates this member variable: -
    -    private void initShapes(){
-    
-        float triangleCoords[] = {
-            // X, Y, Z
-            -0.5f, -0.25f, 0,
-             0.5f, -0.25f, 0,
-             0.0f,  0.559016994f, 0
-        }; 
-        
-        // initialize vertex Buffer for triangle  
-        ByteBuffer vbb = ByteBuffer.allocateDirect(
-                // (# of coordinate values * 4 bytes per float)
-                triangleCoords.length * 4); 
-        vbb.order(ByteOrder.nativeOrder());
-        triangleVB = vbb.asFloatBuffer();
-        triangleVB.put(triangleCoords);
-        triangleVB.position(0);
-    
-    }
-
    -

    This method defines a two-dimensional triangle shape with three equal sides.

    -
    3. -
  3. Modify your onSurfaceCreated() method to initialize your triangle: -
    -    public void onSurfaceCreated(GL10 unused, EGLConfig config) {
-    
-        // Set the background frame color
-        GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
-        
-        // initialize the triangle vertex array
-        initShapes();
-    }
-
    -

    Warning: Shapes and other static objects should be initialized - once in your onSurfaceCreated() method for best performance. Avoid initializing the - new objects in onDrawFrame(), as this causes the system to re-create the objects - for every frame redraw and slows down your application. -

    -
    4. - -
- -

Draw the Triangle

- -

Now that you have defined a shape to draw, you can now use the OpenGL APIs to draw the - object. In order to do this with OpenGL ES 2.0, you must define a vertex shader and a -fragment shader to describe how to draw your shape.

- -

To draw the triangle with OpenGL:

- -
    -
  1. In your HelloOpenGLES20Renderer class, define a vertex shader and a fragment -shader. -
    -    private final String vertexShaderCode = 
-        "attribute vec4 vPosition;    \n" +
-        "void main(){         \n" +
-        " gl_Position = vPosition;  \n" +
-        "}                \n";
-    
-    private final String fragmentShaderCode = 
-        "precision mediump float; \n" +
-        "void main(){       \n" +
-        " gl_FragColor = vec4 (0.63671875, 0.76953125, 0.22265625, 1.0); \n" +
-        "} \n";
-
    -
    2. -
  2. In your HelloOpenGLES20Renderer class, create a method for loading the shaders. -
    -    private int loadShader(int type, String shaderCode){
-    
-        int shader = GLES20.glCreateShader(type);
-        
-        GLES20.glShaderSource(shader, shaderCode);
-        GLES20.glCompileShader(shader);
-        
-        return shader;
-    }
-
    -
    3. - -
  3. Add the following members to your HelloOpenGLES20Renderer class for an OpenGL -Program. -
    -    private int mProgram;
-    private int maPositionHandle;
-
    -
    4. - -
  4. Modify your onSurfaceCreated() method to load the shaders and attach them to a -OpenGL Program. -
    -    public void onSurfaceCreated(GL10 unused, EGLConfig config) {
-    
-        // Set the background frame color
-        GLES20.glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
-        
-        // initialize the triangle vertex array
-        initShapes();
-        
-        // Create shaders for shape and attach to program
-        int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode);
-        int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode);
-        
-        mProgram = GLES20.glCreateProgram();
-        GLES20.glAttachShader(mProgram, vertexShader);
-        GLES20.glAttachShader(mProgram, fragmentShader);
-        GLES20.glLinkProgram(mProgram);
-        
-        maPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
-    }
-
    -

    At this point, you are ready to draw the triangle object in the OpenGL frame.

    -
    5. - -
  5. Modify your onDrawFrame() method to draw the triangle. -
    -    public void onDrawFrame(GL10 unused) {
-        
-        // Redraw background color
-        GLES20.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
-    
-        // Specify a program with shaders
-        GLES20.glUseProgram(mProgram);
-        
-        // Prepare the triangle data
-        GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, 12, triangleVB);
-        GLES20.glEnableVertexAttribArray(maPositionHandle);
-        
-        // Draw the triangle
-        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);
-    }
-
    -

    Note: Since the triangle is stationary at this point, the system is redrawing the - object repeatedly in exactly the same place and so is not the most efficient use of the OpenGL - graphics pipeline. In a later section, we add motion to the object to - justify this use of processing power.

    -
    6. -
- -

Try running this example application on your emulator or test device and -you should see something like this:

- - - -

There are a few problems with this example. First of all, it's not going to impress your -friends. Secondly, the triangle is a bit squashed and changes shape when you change the screen -orientation of the test device. The reason the shape is skewed is due to the fact that the object is -being rendered in a frame which is not perfectly square. We fix that problem in the -next section.

- -

Using Projection and Views

- -

OpenGL Projection and Views provide a way to calculate the coordinates of graphic objects in -realistic proportions on graphics displays of any size. One of the basic problems in displaying -graphics is that Android device displays are typically not square and—by default—OpenGL -happily maps a perfectly square, uniform coordinate system onto your typically non-square -screen.

- - - -

The illustration above shows the uniform coordinate system assumed for an OpenGL frame on the - left, and how these coordinates actually map to a typical device screen in landscape orientation - on the right. To solve this problem, you can apply OpenGL projection modes and views to transform - object coordinates so your graphic objects have the correct proportions on any display.

- -

To use a projection transformation on your triangle:

-
    -
  1. Add the following members to your HelloOpenGLES20Renderer class. -
    -    private int muMVPMatrixHandle;
-    private float[] mMVPMatrix = new float[16];
-    private float[] mMMatrix = new float[16];
-    private float[] mVMatrix = new float[16];
-    private float[] mProjMatrix = new float[16];
-
    -
    2. -
  2. Modify your vertexShaderCode string to add a variable for a model view -projection matrix. -
    -    private final String vertexShaderCode = 
-        "uniform mat4 uMVPMatrix;   \n" +
-        "attribute vec4 vPosition;  \n" +
-        "void main(){               \n" +
-        " gl_Position = uMVPMatrix * vPosition; \n" +
-        "}  \n";
-
    -
    3. -
  3. Modify your onSurfaceChanged() method to reference the uMVPMatrix -shader variable you added and define a view transformation matrix. -
    -    public void onSurfaceCreated(GL10 unused, EGLConfig config) {
-        ...
-        maPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");
-        
-        muMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix");
-        Matrix.setLookAtM(mVMatrix, 0, 0, 0, -3, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
-    }
-
    -
    4. -
  4. Next, modify your onSurfaceChanged() method to calculate the device screen -ration and create a projection matrix. -
    -    public void onSurfaceChanged(GL10 unused, int width, int height) {
-        GLES20.glViewport(0, 0, width, height);
-        
-        float ratio = (float) width / height;
-        Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 3, 7);
-    }  
-
    -
    5. -
  5. Finally, modify your onDrawFrame() method to apply the transformation. -
    -    public void onDrawFrame(GL10 unused) {
-        ...
-        // Apply a ModelView Projection transformation
-        Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mVMatrix, 0);
-        GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);
-        
-        // Draw the triangle
-        GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);        
-    }
-
    -
    6. -
- -

Try running this updated application on your emulator or test device and you should see -something like this:

- - - -

Now that you have applied this transformation, the triangle has three equal sides, instead of the -squashed display in the earlier version.

- - -

Adding Motion

- -

While it may be interesting exercise to create static graphic objects with OpenGL ES, chances -are you want at least some of your objects to move. In this section, we add motion to to our -triangle by rotating it.

- -

To add rotation to your triangle:

-
    -
  1. Add an additional tranformation matrix member to your HelloOpenGLES20Renderer -class. - 
    -      private float[] mMMatrix = new float[16];
-
    -
  2. Modify your onDrawFrame() method to rotate the triangle object: -
    -    public void onDrawFrame(GL10 gl) {
-        ...
-    
-        // Create a rotation for the triangle
-        long time = SystemClock.uptimeMillis() % 4000L;
-        float angle = 0.090f * ((int) time);
-        Matrix.setRotateM(mMMatrix, 0, angle, 0, 0, 1.0f);
-        Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0);
-        Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0);
-        
-        // Apply a ModelView Projection transformation
-        //Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mVMatrix, 0);
-        GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);
-        
-        // Draw the triangle
-        ...
-    }
-
    -
    3. -
- -

Run the application with this code and your triangle should rotate around its center.

- - - -

Additional Resources

- -

Be sure to check out the OpenGL ES code samples are available in the -API -Demos sample application and listed in Related Samples -sidebar above. -

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