Android Open Source - android_effects View Stars

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License

The source code is released under:

Apache License

Java Source Code

/*
   Copyright 2012 Harri Smatt/*from   w w w. ja  v  a2s.  c  o m*/

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
 */

package fi.harism.effects;

import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Comparator;

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

import android.content.Context;
import android.opengl.GLES20;
import android.opengl.Matrix;
import android.os.SystemClock;

public class ViewStars extends ViewBase {

  private ByteBuffer mBufferVertices;
  private long mLastRenderTime = -1;
  private float[] mMatrixModelViewProjection = new float[16];
  private float[] mMatrixProjection = new float[16];
  private float[] mMatrixView = new float[16];
  private boolean[] mShaderCompilerSupport = new boolean[1];
  private EffectsShader mShaderStar = new EffectsShader();
  private Star[] mStarArray = new Star[2000];

  public ViewStars(Context context) {
    super(context);

    for (int i = 0; i < mStarArray.length; ++i) {
      mStarArray[i] = new Star();
    }

    final byte[] VERTICES = { -1, 1, -1, -1, 1, 1, 1, -1 };
    mBufferVertices = ByteBuffer.allocateDirect(2 * 4);
    mBufferVertices.put(VERTICES).position(0);

    setEGLContextClientVersion(2);
    setRenderer(this);
    setRenderMode(RENDERMODE_CONTINUOUSLY);
  }

  @Override
  public void onDrawFrame(GL10 unused) {
    GLES20.glClearColor(0f, 0f, 0f, 1f);
    GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);

    if (mShaderCompilerSupport[0] == false) {
      return;
    }

    GLES20.glEnable(GLES20.GL_BLEND);
    GLES20.glBlendFunc(GLES20.GL_SRC_ALPHA, GLES20.GL_ONE_MINUS_SRC_ALPHA);

    long time = SystemClock.uptimeMillis();

    if (mLastRenderTime == -1) {
      for (Star star : mStarArray) {
        star.randomize();
        star.mPosition[2] = (float) (Math.random() * 4 - 2);
      }
      mLastRenderTime = time;
    }

    float t = (time - mLastRenderTime) / 1000f;
    mLastRenderTime = time;

    mShaderStar.useProgram();

    GLES20.glUniformMatrix4fv(
        mShaderStar.getHandle("uModelViewProjectionM"), 1, false,
        mMatrixModelViewProjection, 0);
    GLES20.glUniform1f(mShaderStar.getHandle("uSize"), .01f);

    GLES20.glVertexAttribPointer(mShaderStar.getHandle("aPosition"), 2,
        GLES20.GL_BYTE, false, 0, mBufferVertices);
    GLES20.glEnableVertexAttribArray(mShaderStar.getHandle("aPosition"));

    for (Star star : mStarArray) {
      star.mPosition[2] += star.mSpeed * t;
      if (star.mPosition[2] > 2) {
        star.randomize();
      }
    }

    Arrays.sort(mStarArray, new Comparator<Star>() {
      @Override
      public int compare(Star arg0, Star arg1) {
        return arg0.mPosition[2] < arg1.mPosition[2] ? -1 : 1;
      }
    });

    for (Star star : mStarArray) {
      GLES20.glUniform3fv(mShaderStar.getHandle("uPosition"), 1,
          star.mPosition, 0);
      GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
    }

    GLES20.glDisable(GLES20.GL_BLEND);

  }

  @Override
  public void onSurfaceChanged(GL10 unused, int width, int height) {
    float aspect = (float) width / height;
    Matrix.perspectiveM(mMatrixProjection, 0, 60f, aspect, .1f, 10f);
    Matrix.setLookAtM(mMatrixView, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0);
    Matrix.multiplyMM(mMatrixModelViewProjection, 0, mMatrixProjection, 0,
        mMatrixView, 0);
    mLastRenderTime = -1;
  }

  @Override
  public void onSurfaceCreated(GL10 unused, EGLConfig config) {
    // Check if shader compiler is supported.
    GLES20.glGetBooleanv(GLES20.GL_SHADER_COMPILER, mShaderCompilerSupport,
        0);

    // If not, show user an error message and return immediately.
    if (!mShaderCompilerSupport[0]) {
      String msg = getContext().getString(R.string.error_shader_compiler);
      showError(msg);
      return;
    }

    try {
      String vertexSource = loadRawString(R.raw.star_vs);
      String fragmentSource = loadRawString(R.raw.star_fs);
      mShaderStar.setProgram(vertexSource, fragmentSource);
    } catch (Exception ex) {
      showError(ex.getMessage());
    }
  }

  private class Star {
    public float[] mPosition = new float[3];
    public float mSpeed;

    public void randomize() {
      mPosition[0] = (float) (Math.random() * 2 - 1);
      mPosition[1] = (float) (Math.random() * 2 - 1);
      mPosition[2] = -2f;
      mSpeed = (float) (Math.random() * 0.2 + 0.2);
    }
  }

}

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