背景グラデーションなサンプルコード

gistfile1.txt

package fuga.glsurfaceviewsample;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff;
import android.opengl.GLSurfaceView;
import android.opengl.GLUtils;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.ViewGroup;
import android.widget.TextView;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;

import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;


public class MainActivity extends Activity {

    private static final String TAG = "MainActivity";
    private GLSurfaceView mGLSurfaceView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        mGLSurfaceView = (MyGLSurfaceView)findViewById(R.id.glsurfaceview);
        mGLSurfaceView.setRenderer(new GLRenderer());
    }

    @Override
    protected void onResume() {
        super.onResume();
        mGLSurfaceView.onResume();
    }

    @Override
    protected void onPause() {
        super.onPause();
        mGLSurfaceView.onPause();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    abstract class GLRendererBase implements GLSurfaceView.Renderer {
        /**
         * ログ出力を行う。
         *
         * @param message
         */
        public void log(String message) {
            Log.i("TAG", message);
        }
    };

    class GLRenderer extends GLRendererBase {
        private int screenWidth, screenHeight;

        /**
         * OpenGLから割り当てられたテクスチャ名
         */
//        private int texture;
        private int [] textures;
        private int [] widths;
        private int [] heights;
        private int textureWidth, textureHeight;
        private float angle;

        /**
         * サーフェイス作成時の処理。
         *
         * @param gl10
         * @param eglconfig
         */
        @Override
        public void onSurfaceCreated(GL10 gl10, EGLConfig eglconfig) {

        }

        /**
         * サーフェイスが変更になった。
         *
         * @param gl10
         * @param w
         *            画面横の長さ（ピクセル）
         * @param h
         *            画面縦の長さ（ピクセル）
         */
        @Override
        public void onSurfaceChanged(GL10 gl10, int w, int h) {
            gl10.glViewport(0, 0, w, h);
            screenWidth = w;
            screenHeight = h;
            angle = -3f;

            final int [] resources = { R.drawable.centerlogo };
            textures = new int[resources.length];
            widths = new int[resources.length];
            heights = new int[resources.length];

            gl10.glEnable(GL10.GL_TEXTURE_2D);
            gl10.glGenTextures(resources.length, textures, 0);

            for (int i = 0; i < resources.length; i++) {
                Bitmap bitmap = null;
                bitmap = BitmapFactory.decodeResource(getResources(), resources[i]);

                widths[i] = bitmap.getWidth();
                heights[i] = bitmap.getHeight();

                gl10.glBindTexture(GL10.GL_TEXTURE_2D, textures[i]);
                GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);

                gl10.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
                gl10.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_NEAREST);

                bitmap.recycle();
            }
        }

        private void setTexture(GL10 gl10, int index) {
            if (index < 0 || index >= textures.length) {
                gl10.glDisable(GL10.GL_TEXTURE_2D);
            } else {
                gl10.glEnable(GL10.GL_TEXTURE_2D);
                gl10.glBindTexture(GL10.GL_TEXTURE_2D, textures[index]);
                textureWidth = widths[index];
                textureHeight = heights[index];
            }
        }

        private void setTextureArea(GL10 gl10, int x, int y, int w, int h) {
            float left = ((float) x / (float) textureWidth), top = ((float) y / (float) textureHeight);

            float right = left + ((float) w / (float) textureWidth);
            float bottom = top + ((float) h / (float) textureHeight);

            // ! 位置情報
            float uv[] = {
                    // ! u v
                    left, top,     // !< 左上
                    left, bottom,  // !< 左下
                    right, top,    // !< 右上
                    right, bottom, // !< 右下
            };

            ByteBuffer bb = ByteBuffer.allocateDirect(uv.length * 4);
            bb.order(ByteOrder.nativeOrder());
            FloatBuffer fb = bb.asFloatBuffer();
            fb.put(uv);
            fb.position(0);

            gl10.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
            gl10.glTexCoordPointer(2, GL10.GL_FLOAT, 0, fb);
        }

        private void drawQuad(GL10 gl10, int x, int y, int w, int h) {
            float left = ((float) x / (float) screenWidth) * 2.0f - 1.0f, top = ((float) y / (float) screenHeight) * 2.0f - 1.0f;

            float right = left + ((float) w / (float) screenWidth) * 2.0f;
            float bottom = top + ((float) h / (float) screenHeight) * 2.0f;

            // ! 上下を反転させる
            top = -top;
            bottom = -bottom;

            // ! 位置情報
            float positions[] = {
                    // ! x y z
                    left, top, 0.0f, // !< 左上
                    left, bottom, 0.0f, // !< 左下
                    right, top, 0.0f, // !< 右上
                    right, bottom, 0.0f, // !< 右下
            };

            ByteBuffer bb = ByteBuffer.allocateDirect(positions.length * 4);
            bb.order(ByteOrder.nativeOrder());
            FloatBuffer fb = bb.asFloatBuffer();
            fb.put(positions);
            fb.position(0);

            gl10.glEnableClientState(GL10.GL_VERTEX_ARRAY);
            gl10.glDisableClientState(GL10.GL_COLOR_ARRAY);
            gl10.glVertexPointer(3, GL10.GL_FLOAT, 0, fb);

            gl10.glMatrixMode(GL10.GL_MODELVIEW);
            final float aspect = (float)screenWidth / (float)screenHeight;

            gl10.glLoadIdentity();

            gl10.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
        }

        private void drawBackground(GL10 gl10) {
            float left = -1f;
            float top = 1f;
            float right = 1f;
            float bottom = -1f;

            // ! 上下を反転させる
            top = -top;
            bottom = -bottom;

            // ! 位置情報
            float positions[] = {
                    // ! x y z
                    left, top, 0.0f, // !< 左上
                    left, bottom, 0.0f, // !< 左下
                    right, top, 0.0f, // !< 右上
                    right, bottom, 0.0f, // !< 右下
            };

            ByteBuffer bb = ByteBuffer.allocateDirect(positions.length * 4);
            bb.order(ByteOrder.nativeOrder());
            FloatBuffer fb = bb.asFloatBuffer();
            fb.put(positions);
            fb.position(0);

            float colors [] = {
                    4f / 255f, 68f / 255f, 154f / 255f, 1f,   // 左下
                    25f / 255f, 140f / 255f, 255f / 255f, 1f, // 左上
                    3f / 255f, 67f / 255f, 153f / 255f, 1f,   // 右下
                    25f / 255f, 140f / 255f, 255f / 255f, 1f, // 右上
            };

            ByteBuffer colorBuffer = ByteBuffer.allocateDirect(colors.length*4);
            colorBuffer.order(ByteOrder.nativeOrder());
            FloatBuffer mColorBuffer = colorBuffer.asFloatBuffer();
            mColorBuffer.put(colors);
            mColorBuffer.position(0);

            gl10.glEnableClientState(GL10.GL_VERTEX_ARRAY);
            gl10.glEnableClientState(GL10.GL_COLOR_ARRAY);
            gl10.glVertexPointer(3, GL10.GL_FLOAT, 0, fb);
            gl10.glColorPointer(4, GL10.GL_FLOAT, 0, mColorBuffer);

            gl10.glMatrixMode(GL10.GL_MODELVIEW);

            gl10.glLoadIdentity();

            gl10.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
        }

        /**
         * 毎フレーム描画処理。
         *
         * @param gl10
         */
        @Override
        public void onDrawFrame(GL10 gl10) {
            gl10.glClearColor(0.0f, 1.0f, 1.0f, 1.0f);
            gl10.glClear(GL10.GL_COLOR_BUFFER_BIT);

            // ! テクスチャ全体のUVを指定する。
            {
                // ! UV情報
                float uv[] = {
                        // ! u v
                        0.0f, 0.0f, // !< 左上
                        0.0f, 1.0f, // !< 左下
                        1.0f, 0.0f, // !< 右上
                        1.0f, 1.0f, // !< 右下
                };

                ByteBuffer bb = ByteBuffer.allocateDirect(uv.length * 4);
                bb.order(ByteOrder.nativeOrder());
                FloatBuffer fb = bb.asFloatBuffer();
                fb.put(uv);
                fb.position(0);

                gl10.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
                gl10.glTexCoordPointer(2, GL10.GL_FLOAT, 0, fb);
            }

            {
                gl10.glEnable(GL10.GL_BLEND);
                gl10.glEnable(GL10.GL_ALPHA);
                gl10.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
            }

            gl10.glPushMatrix();
            setTexture(gl10, -1);
            drawBackground(gl10);
            gl10.glPopMatrix();

            gl10.glPushMatrix();
            setTexture(gl10, 0);
            setTextureArea(gl10, 0, 0, textureWidth, textureHeight);
            drawQuad(gl10,
                    screenWidth / 2 - textureWidth / 2,
                    screenHeight / 9 - textureHeight / 2,
                    textureWidth,
                    textureHeight);
            gl10.glPopMatrix();

        }
    }
}