Android Chromoting: Add skybox environment for the Cardboard desktop activity.

Surround the view environment with a skybox environment.

Note: the skybox image could be replaced easily later.

BUG = 516871

Review URL: https://codereview.chromium.org/1271333002

Cr-Commit-Position: refs/heads/master@{#343950}

3 files changed, 410 insertions, 20 deletions

diff --git a/remoting/android/java/src/org/chromium/chromoting/CardboardDesktopRenderer.java b/remoting/android/java/src/org/chromium/chromoting/CardboardDesktopRenderer.java
index 33aa5e8..5d5aabb 100644
--- a/remoting/android/java/src/org/chromium/chromoting/CardboardDesktopRenderer.java
+++ b/remoting/android/java/src/org/chromium/chromoting/CardboardDesktopRenderer.java
@@ -4,8 +4,9 @@
 
 package org.chromium.chromoting;
 
-import android.content.Context;
+import android.app.Activity;
 import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
 import android.graphics.PointF;
 import android.opengl.GLES20;
 import android.opengl.Matrix;
@@ -15,6 +16,7 @@ import com.google.vrtoolkit.cardboard.Eye;
 import com.google.vrtoolkit.cardboard.HeadTransform;
 import com.google.vrtoolkit.cardboard.Viewport;
 
+import org.chromium.base.Log;
 import org.chromium.chromoting.jni.JniInterface;
 
 import java.nio.ByteBuffer;
@@ -37,6 +39,7 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
     private static final float DESKTOP_POSITION_X = 0.0f;
     private static final float DESKTOP_POSITION_Y = 0.0f;
     private static final float DESKTOP_POSITION_Z = -2.0f;
+    private static final float HALF_SKYBOX_SIZE = 100.0f;
 
     // Allows user to click even when looking outside the desktop
     // but within edge margin.
@@ -55,6 +58,43 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
             1.0f, 0.0f
     });
 
+    private static final FloatBuffer SKYBOX_POSITION_COORDINATES = makeFloatBuffer(new float[] {
+            -HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE,  // (0) Top-left near
+            HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE,  // (1) Top-right near
+            -HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE,  // (2) Bottom-left near
+            HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE,  // (3) Bottom-right near
+            -HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE,  // (4) Top-left far
+            HALF_SKYBOX_SIZE,  HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE,  // (5) Top-right far
+            -HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE,  // (6) Bottom-left far
+            HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE, -HALF_SKYBOX_SIZE  // (7) Bottom-right far
+    });
+
+    private static final ByteBuffer SKYBOX_INDICES_BYTE_BUFFER = ByteBuffer.wrap(new byte[] {
+            // Front
+            1, 3, 0,
+            0, 3, 2,
+
+            // Back
+            4, 6, 5,
+            5, 6, 7,
+
+            // Left
+            0, 2, 4,
+            4, 2, 6,
+
+            // Right
+            5, 7, 1,
+            1, 7, 3,
+
+            // Top
+            5, 1, 4,
+            4, 1, 0,
+
+            // Bottom
+            6, 2, 7,
+            7, 2, 3
+    });
+
     private static final String DESKTOP_VERTEX_SHADER =
             "uniform mat4 u_CombinedMatrix;"
             + "attribute vec4 a_Position;"
@@ -87,12 +127,47 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
             + "  gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);"
             + "}";
 
-    private final Context mActivityContext;
+    private static final String SKYBOX_VERTEX_SHADER =
+            "uniform mat4 u_CombinedMatrix;"
+            + "attribute vec3 a_Position;"
+            + "varying vec3 v_Position;"
+            + "void main() {"
+            + "  v_Position = a_Position;"
+            // Make sure to convert from the right-handed coordinate system of the
+            // world to the left-handed coordinate system of the cube map, otherwise,
+            // our cube map will still work but everything will be flipped.
+            + "  v_Position.z = -v_Position.z;"
+            + "  gl_Position = u_CombinedMatrix * vec4(a_Position, 1.0);"
+            + "  gl_Position = gl_Position.xyww;"
+            + "}";
 
-    private float mHalfDesktopWidth;
+    private static final String SKYBOX_FRAGMENT_SHADER =
+            "precision mediump float;"
+            + "uniform samplerCube u_TextureUnit;"
+            + "varying vec3 v_Position;"
+            + "void main() {"
+            + "  gl_FragColor = textureCube(u_TextureUnit, v_Position);"
+            + "}";
 
-    // Flag to indicate whether reload the desktop texture or not.
-    private boolean mReloadTexture;
+    private static final String ASSETS_URI_PREFIX =
+            "https://dl.google.com/chrome-remote-desktop/android-assets/";;
+
+    private static final String[] SKYBOX_IMAGE_URIS = new String[] {
+        "https://dl.google.com/chrome-remote-desktop/android-assets/room_left.png",
+        "https://dl.google.com/chrome-remote-desktop/android-assets/room_right.png",
+        "https://dl.google.com/chrome-remote-desktop/android-assets/room_bottom.png",
+        "https://dl.google.com/chrome-remote-desktop/android-assets/room_top.png",
+        "https://dl.google.com/chrome-remote-desktop/android-assets/room_back.png",
+        "https://dl.google.com/chrome-remote-desktop/android-assets/room_front.png"
+    };
+
+    private static final String[] SKYBOX_IMAGE_NAMES = new String[] {
+        "skybox_left", "skybox_right", "skybox_bottom", "skybox_top", "skybox_back", "skybox_front"
+    };
+
+    private final Activity mActivity;
+
+    private float mHalfDesktopWidth;
 
     private float[] mCameraMatrix;
     private float[] mViewMatrix;
@@ -103,6 +178,8 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
     private float[] mDesktopCombinedMatrix;
     private float[] mEyePointModelMatrix;
     private float[] mEyePointCombinedMatrix;
+    private float[] mSkyboxModelMatrix;
+    private float[] mSkyboxCombinedMatrix;
 
     // Direction that user is looking towards.
     private float[] mForwardVector;
@@ -123,6 +200,16 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
     private int mEyePointProgramHandle;
     private int mEyePointPositionHandle;
     private int mEyePointCombinedMatrixHandle;
+    private int mSkyboxVertexShaderHandle;
+    private int mSkyboxFragmentShaderHandle;
+    private int mSkyboxProgramHandle;
+    private int mSkyboxPositionHandle;
+    private int mSkyboxCombinedMatrixHandle;
+    private int mSkyboxTextureUnitHandle;
+    private int mSkyboxTextureDataHandle;
+
+    // Flag to indicate whether reload the desktop texture or not.
+    private boolean mReloadTexture;
 
     /** Lock to allow multithreaded access to mReloadTexture. */
     private Object mReloadTextureLock = new Object();
@@ -136,8 +223,17 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
 
     private FloatBuffer mDesktopCoordinates;
 
-    public CardboardDesktopRenderer(Context context) {
-        mActivityContext = context;
+    // Flag to signal that the skybox images are fully decoded and should be loaded
+    // into the OpenGL textures.
+    private boolean mLoadSkyboxImagesTexture;
+
+    // Lock to allow multithreaded access to mLoadSkyboxImagesTexture.
+    private Object mLoadSkyboxImagesTextureLock = new Object();
+
+    private ChromotingDownloadManager mDownloadManager;
+
+    public CardboardDesktopRenderer(Activity activity) {
+        mActivity = activity;
         mReloadTexture = false;
 
         mCameraMatrix = new float[16];
@@ -147,11 +243,24 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
         mDesktopCombinedMatrix = new float[16];
         mEyePointModelMatrix = new float[16];
         mEyePointCombinedMatrix = new float[16];
+        mSkyboxModelMatrix = new float[16];
+        mSkyboxCombinedMatrix = new float[16];
 
         mForwardVector = new float[3];
         mEyePositionVector = new float[3];
 
         attachRedrawCallback();
+
+        mDownloadManager = new ChromotingDownloadManager(mActivity, SKYBOX_IMAGE_NAMES,
+                SKYBOX_IMAGE_URIS, new ChromotingDownloadManager.Callback() {
+                    @Override
+                    public void onBatchDownloadComplete() {
+                        synchronized (mLoadSkyboxImagesTextureLock) {
+                            mLoadSkyboxImagesTexture = true;
+                        }
+                    }
+                });
+        mDownloadManager.download();
     }
 
     // This can be called on any thread.
@@ -203,6 +312,23 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
         mEyePointCombinedMatrixHandle =
                 GLES20.glGetUniformLocation(mEyePointProgramHandle, "u_CombinedMatrix");
 
+        // Set handlers for skybox drawing.
+        GLES20.glEnable(GLES20.GL_TEXTURE_CUBE_MAP);
+        mSkyboxVertexShaderHandle =
+                ShaderHelper.compileShader(GLES20.GL_VERTEX_SHADER, SKYBOX_VERTEX_SHADER);
+        mSkyboxFragmentShaderHandle =
+                ShaderHelper.compileShader(GLES20.GL_FRAGMENT_SHADER, SKYBOX_FRAGMENT_SHADER);
+        mSkyboxProgramHandle = ShaderHelper.createAndLinkProgram(mSkyboxVertexShaderHandle,
+                mSkyboxFragmentShaderHandle,
+                new String[] {"a_Position", "u_CombinedMatrix", "u_TextureUnit"});
+        mSkyboxPositionHandle =
+                GLES20.glGetAttribLocation(mSkyboxProgramHandle, "a_Position");
+        mSkyboxCombinedMatrixHandle =
+                GLES20.glGetUniformLocation(mSkyboxProgramHandle, "u_CombinedMatrix");
+        mSkyboxTextureUnitHandle =
+                GLES20.glGetUniformLocation(mSkyboxProgramHandle, "u_TextureUnit");
+        mSkyboxTextureDataHandle = TextureHelper.createTextureHandle();
+
         // Position the eye at the origin.
         float eyeX = 0.0f;
         float eyeY = 0.0f;
@@ -232,6 +358,7 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
         headTransform.getForwardVector(mForwardVector, 0);
         getLookingPosition();
         maybeLoadTexture(mTextureDataHandle);
+        maybeLoadCubeMapAndCleanImages(mSkyboxTextureDataHandle);
     }
 
     @Override
@@ -243,6 +370,7 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
 
         mProjectionMatrix = eye.getPerspective(Z_NEAR, Z_FAR);
 
+        drawSkybox();
         drawDesktop();
         drawEyePoint();
     }
@@ -253,7 +381,15 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
         GLES20.glDeleteShader(mDesktopFragmentShaderHandle);
         GLES20.glDeleteShader(mEyePointVertexShaderHandle);
         GLES20.glDeleteShader(mEyePointFragmentShaderHandle);
-        GLES20.glDeleteTextures(1, new int[]{mTextureDataHandle}, 0);
+        GLES20.glDeleteShader(mSkyboxVertexShaderHandle);
+        GLES20.glDeleteShader(mSkyboxFragmentShaderHandle);
+        GLES20.glDeleteTextures(1, new int[] {mTextureDataHandle}, 0);
+        GLES20.glDeleteTextures(1, new int[] {mSkyboxTextureDataHandle}, 0);
+        mActivity.runOnUiThread(new Runnable() {
+            public void run() {
+                mDownloadManager.close();
+            }
+        });
     }
 
     @Override
@@ -336,6 +472,28 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
         GLES20.glDrawArrays(GLES20.GL_POINTS, 0, totalPointNumber);
     }
 
+    private void drawSkybox() {
+        GLES20.glUseProgram(mSkyboxProgramHandle);
+
+        Matrix.setIdentityM(mSkyboxModelMatrix, 0);
+        Matrix.multiplyMM(mSkyboxCombinedMatrix, 0, mViewMatrix, 0, mSkyboxModelMatrix, 0);
+        Matrix.multiplyMM(mSkyboxCombinedMatrix, 0, mProjectionMatrix,
+                0, mSkyboxCombinedMatrix, 0);
+
+        GLES20.glUniformMatrix4fv(mSkyboxCombinedMatrixHandle, 1, false,
+                mSkyboxCombinedMatrix, 0);
+        GLES20.glVertexAttribPointer(mSkyboxPositionHandle, POSITION_DATA_SIZE, GLES20.GL_FLOAT,
+                false, 0, SKYBOX_POSITION_COORDINATES);
+        GLES20.glEnableVertexAttribArray(mSkyboxPositionHandle);
+
+        GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
+        GLES20.glBindTexture(GLES20.GL_TEXTURE_CUBE_MAP, mSkyboxTextureDataHandle);
+        GLES20.glUniform1i(mSkyboxTextureUnitHandle, 0);
+
+        GLES20.glDrawElements(GLES20.GL_TRIANGLES, 36, GLES20.GL_UNSIGNED_BYTE,
+                SKYBOX_INDICES_BYTE_BUFFER);
+    }
+
     /**
      * Returns coordinates in units of pixels in the desktop bitmap.
      * This can be called on any thread.
@@ -387,7 +545,7 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
         }
     }
 
-    /*
+    /**
      * Return true if user is looking at the space to the left of the dekstop.
      * This method can be called on any thread.
      */
@@ -397,7 +555,7 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
         }
     }
 
-    /*
+    /**
      * Return true if user is looking at the space to the right of the dekstop.
      * This method can be called on any thread.
      */
@@ -488,4 +646,53 @@ public class CardboardDesktopRenderer implements CardboardView.StereoRenderer {
             });
         }
     }
+
+    /**
+     * Decode all skybox images to Bitmap files and return them.
+     * Only call this method when we have complete skybox images.
+     * @throws DecodeFileException if BitmapFactory fails to decode file.
+     */
+    private Bitmap[] decodeSkyboxImages() throws DecodeFileException {
+        Bitmap[] result = new Bitmap[SKYBOX_IMAGE_NAMES.length];
+        String fileDirectory = mDownloadManager.getDownloadDirectory();
+        for (int i = 0; i < SKYBOX_IMAGE_NAMES.length; i++) {
+            result[i] = BitmapFactory.decodeFile(fileDirectory + "/" + SKYBOX_IMAGE_NAMES[i]);
+            if (result[i] == null) {
+                throw new DecodeFileException();
+            }
+        }
+        return result;
+    }
+
+    /**
+     * Link the skybox images with given texture handle and clean images at the end.
+     * Only call this method when we have complete skybox images.
+     */
+    private void maybeLoadCubeMapAndCleanImages(int textureHandle) {
+        synchronized (mLoadSkyboxImagesTextureLock) {
+            if (!mLoadSkyboxImagesTexture) {
+                return;
+            }
+            mLoadSkyboxImagesTexture = false;
+        }
+
+        Bitmap[] images;
+        try {
+            images = decodeSkyboxImages();
+        } catch (DecodeFileException e) {
+            Log.i(TAG, "Failed to decode image files.");
+            return;
+        }
+
+        TextureHelper.linkCubeMap(textureHandle, images);
+        for (Bitmap image : images) {
+            image.recycle();
+        }
+    }
+
+    /**
+     * Exception when BitmapFactory fails to decode file.
+     */
+    private static class DecodeFileException extends Exception {
+    }
 }
\ No newline at end of file
diff --git a/remoting/android/java/src/org/chromium/chromoting/ChromotingDownloadManager.java b/remoting/android/java/src/org/chromium/chromoting/ChromotingDownloadManager.java
new file mode 100644
index 0000000..5d08f45
--- /dev/null
+++ b/remoting/android/java/src/org/chromium/chromoting/ChromotingDownloadManager.java
@@ -0,0 +1,146 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chromoting;
+
+import android.app.Activity;
+import android.app.DownloadManager;
+import android.app.DownloadManager.Query;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.database.Cursor;
+import android.net.Uri;
+import android.os.Environment;
+
+import java.io.File;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class that manages download operation for Chromoting activity.
+ */
+public class ChromotingDownloadManager {
+    /**
+     * Callback for download manager. This will be executed on application's main thread.
+     */
+    public interface Callback {
+        /**
+         * Called when batch download is successfully finished.
+         */
+        public void onBatchDownloadComplete();
+    }
+
+    private Activity mActivity;
+    private BroadcastReceiver mDownloadReceiver;
+    private DownloadManager mDownloadManager;
+    private Set<Long> mUnfinishedDownloadIds;
+    private Callback mCallback;
+    private String[] mNames;
+    private String[] mUris;
+
+    public ChromotingDownloadManager(Activity activity, String[] names, String[] uris,
+            Callback callback) {
+        assert names.length == uris.length;
+
+        mActivity = activity;
+        mCallback = callback;
+        mDownloadManager =
+                (DownloadManager) mActivity.getSystemService(Context.DOWNLOAD_SERVICE);
+        mNames = names.clone();
+        mUris = uris.clone();
+        mUnfinishedDownloadIds = new HashSet<Long>();
+    }
+
+    /**
+     * Download files according to given URIs and store them as given names.
+     */
+    public void download() {
+        for (int i = 0; i < mNames.length; i++) {
+            if (needToBeDownloaded(i)) {
+                DownloadManager.Request request =
+                        new DownloadManager.Request(Uri.parse(mUris[i]));
+                request.setDestinationInExternalFilesDir(mActivity.getApplicationContext(),
+                        Environment.DIRECTORY_DOWNLOADS, mNames[i]);
+                mUnfinishedDownloadIds.add(mDownloadManager.enqueue(request));
+            }
+        }
+
+        if (mUnfinishedDownloadIds.isEmpty()) {
+            mActivity.runOnUiThread(new Runnable() {
+                public void run() {
+                    mCallback.onBatchDownloadComplete();
+                }
+            });
+        } else {
+            mDownloadReceiver = new BroadcastReceiver() {
+                @Override
+                public void onReceive(Context context, Intent intent) {
+                    String action = intent.getAction();
+                    if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
+                        Query query = new Query();
+                        query.setFilterById(convertToArray(mUnfinishedDownloadIds));
+                        query.setFilterByStatus(DownloadManager.STATUS_SUCCESSFUL);
+                        Cursor cursor = mDownloadManager.query(query);
+
+                        // Delete finished download id from unfinished download id set.
+                        for (int i = 0; i < cursor.getCount(); i++) {
+                            cursor.moveToPosition(i);
+                            int downloadIdIndex = cursor.getColumnIndex(DownloadManager.COLUMN_ID);
+                            mUnfinishedDownloadIds.remove(cursor.getLong(downloadIdIndex));
+                        }
+
+                        if (mUnfinishedDownloadIds.isEmpty()) {
+                            mCallback.onBatchDownloadComplete();
+                        }
+                        cursor.close();
+                    }
+                }
+            };
+
+            mActivity.registerReceiver(mDownloadReceiver,
+                    new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
+        }
+    }
+
+    /**
+     * Perform necessary operations to close the download manager.
+     */
+    public void close() {
+        if (!mUnfinishedDownloadIds.isEmpty()) {
+            mDownloadManager.remove(convertToArray(mUnfinishedDownloadIds));
+        }
+        if (mDownloadReceiver != null) {
+            mActivity.unregisterReceiver(mDownloadReceiver);
+        }
+    }
+
+    /**
+     * Check whether the file corresponding to the given index needs to be downloaded.
+     */
+    private boolean needToBeDownloaded(int index) {
+        return !new File(getDownloadDirectory() + "/" + mNames[index]).exists();
+    }
+
+    /**
+     * Get download directory path.
+     */
+    public String getDownloadDirectory() {
+        return mActivity.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).toString();
+    }
+
+    /**
+     * Convert a Set of Long to an array of long.
+     */
+    private long[] convertToArray(Set<Long> data) {
+        long[] result = new long[data.size()];
+        int index = 0;
+        for (long number : data) {
+            result[index] = number;
+            index++;
+        }
+        return result;
+    }
+}
\ No newline at end of file
diff --git a/remoting/android/java/src/org/chromium/chromoting/TextureHelper.java b/remoting/android/java/src/org/chromium/chromoting/TextureHelper.java
index f5708c8..fb710eb 100644
--- a/remoting/android/java/src/org/chromium/chromoting/TextureHelper.java
+++ b/remoting/android/java/src/org/chromium/chromoting/TextureHelper.java
@@ -4,9 +4,25 @@
 
 package org.chromium.chromoting;
 
+import static android.opengl.GLES20.GL_LINEAR;
+import static android.opengl.GLES20.GL_NEAREST;
+import static android.opengl.GLES20.GL_TEXTURE_2D;
+import static android.opengl.GLES20.GL_TEXTURE_CUBE_MAP;
+import static android.opengl.GLES20.GL_TEXTURE_CUBE_MAP_NEGATIVE_X;
+import static android.opengl.GLES20.GL_TEXTURE_CUBE_MAP_NEGATIVE_Y;
+import static android.opengl.GLES20.GL_TEXTURE_CUBE_MAP_NEGATIVE_Z;
+import static android.opengl.GLES20.GL_TEXTURE_CUBE_MAP_POSITIVE_X;
+import static android.opengl.GLES20.GL_TEXTURE_CUBE_MAP_POSITIVE_Y;
+import static android.opengl.GLES20.GL_TEXTURE_CUBE_MAP_POSITIVE_Z;
+import static android.opengl.GLES20.GL_TEXTURE_MAG_FILTER;
+import static android.opengl.GLES20.GL_TEXTURE_MIN_FILTER;
+import static android.opengl.GLES20.glBindTexture;
+import static android.opengl.GLES20.glDeleteTextures;
+import static android.opengl.GLES20.glGenTextures;
+import static android.opengl.GLES20.glTexParameteri;
+import static android.opengl.GLUtils.texImage2D;
+
 import android.graphics.Bitmap;
-import android.opengl.GLES20;
-import android.opengl.GLUtils;
 
 /**
  * Helper class for working with OpenGL textures.
@@ -18,7 +34,7 @@ public class TextureHelper {
      */
     public static int createTextureHandle() {
         int[] textureDataHandle = new int[1];
-        GLES20.glGenTextures(1, textureDataHandle, 0);
+        glGenTextures(1, textureDataHandle, 0);
         if (textureDataHandle[0] != 0) {
             return textureDataHandle[0];
         } else {
@@ -32,17 +48,38 @@ public class TextureHelper {
      */
     public static void linkTexture(int textureDataHandle, Bitmap bitmap) {
         // Delete previously attached texture.
-        GLES20.glDeleteTextures(1, new int[]{textureDataHandle}, 0);
+        glDeleteTextures(1, new int[]{textureDataHandle}, 0);
 
         // Bind to the texture in OpenGL.
-        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureDataHandle);
+        glBindTexture(GL_TEXTURE_2D, textureDataHandle);
 
-        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
-                GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST);
-        GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
-                GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D,
+                GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D,
+                GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 
         // Load the bitmap into the bound texture.
-        GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
+        texImage2D(GL_TEXTURE_2D, 0, bitmap, 0);
+    }
+
+    /**
+     * Link the cubemap images with a given texture handle.
+     */
+    public static void linkCubeMap(int textureDataHandle, Bitmap[] cubeBitmaps) {
+        glBindTexture(GL_TEXTURE_CUBE_MAP, textureDataHandle);
+
+        // Linear filtering for minification and magnification.
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        // Link left, right, bottom, top, back and front image in order.
+        texImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, 0, cubeBitmaps[0], 0);
+        texImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X, 0, cubeBitmaps[1], 0);
+
+        texImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, 0, cubeBitmaps[2], 0);
+        texImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Y, 0, cubeBitmaps[3], 0);
+
+        texImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, cubeBitmaps[4], 0);
+        texImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, cubeBitmaps[5], 0);
     }
 }
\ No newline at end of file