android OpenGL开发 一个爆炸效果的粒子发生器

首先声明这个程序基本上都是nehe的OpenGL教学的第十九课内容，我只是把他的代码用android表现了出来，由于本人对算法的了解不是很多，所以这只是一个很简单的例子（但我自己也是花了好长时间才弄出来的），仅供刚刚接触OpenGL的同学参考，有什么错误的地方欢迎指正，你可以说说你自己的想法，互相交流，下面把我的代码附在下面，有兴趣的同学可以研究一下：

下面是我们的自定义Renderer，主要的难点就是算法，也就是对particle的运行轨迹的控制，希望在OpenGL上有所成就的同学给我们一些好的建议。

public class MyRenderer extends GLSurfaceView implements Renderer {private float slowdown = 20.f; // Slow Down Particlesprivate float zoom = -40.0f; // Used To Zoom Outprivate int[] texture = new int[1];// Storage For Our Particle Textureprivate Random random = new Random(); // to generate a int value randomlyprivate FloatBuffer vertexBuffer; // to hold the particle's verticesprivate FloatBuffer textureBuffer; // to hold the particle's texture// verticesprivate float[] textureCoordinate = { 0.0f, 0.f, 1.0f, 0.0f, 0.0f, 1.0f,1.0f, 1.0f }; // the particle's texture coordinateprivate Particle[] particles = new Particle[1000];// to hold the particle// object arrayprivate Context context;// the activity context/** * the method to generate a FloatBuffer reference with pass a float array * */private FloatBuffer formatFloatBuffer(float[] array) {ByteBuffer bb = ByteBuffer.allocateDirect(array.length * 4);bb.order(ByteOrder.nativeOrder());FloatBuffer fb;fb = bb.asFloatBuffer();fb.put(array);fb.position(0);return fb;}// the particle color arrayprivate float colors[][] = { { 1.0f, 0.5f, 0.5f }, { 1.0f, 0.75f, 0.5f },{ 1.0f, 1.0f, 0.5f }, { 0.75f, 1.0f, 0.5f }, { 0.5f, 1.0f, 0.5f },{ 0.5f, 1.0f, 0.75f }, { 0.5f, 1.0f, 1.0f }, { 0.5f, 0.75f, 1.0f },{ 0.5f, 0.5f, 1.0f }, { 0.75f, 0.5f, 1.0f }, { 1.0f, 0.5f, 1.0f },{ 1.0f, 0.5f, 0.75f } };/** * the MyRenderer constructor * */public MyRenderer(Context context) {super(context);this.setRenderer(this);this.context = context;}/** * the method to initiate the particle objects *  * */private void initParticals() {for (int i = 0; i < particles.length; i++) {particles[i] = new Particle();particles[i].active = true;particles[i].life = 1.0f;particles[i].fade = (float) (random.nextInt(10) % 100) / 1000.0f + 0.003f;particles[i].r = colors[random.nextInt(12)][0];particles[i].g = colors[random.nextInt(12)][1];particles[i].b = colors[random.nextInt(12)][2];particles[i].xi = (float) ((random.nextInt(100) % 50) - 26.0f) * 10.0f;particles[i].yi = (float) ((random.nextInt(100) % 50) - 25.0f) * 10.0f;particles[i].zi = (float) ((random.nextInt(100) % 50) - 25.0f) * 10.0f;particles[i].xg = 0.0f;particles[i].yg = -0.8f;particles[i].zg = 0.0f;}}/** * draws the whole particles and change the each one's attribute after draws * it * */private void drawParticle(GL10 gl) {for (int i = 0; i < particles.length; i++) {if (particles[i].active) {float temVectex[] = { particles[i].x + 0.5f,particles[i].y + 0.5f, particles[i].z + zoom,particles[i].x + 0.5f, particles[i].y - 0.5f,particles[i].z + zoom, particles[i].x - 0.5f,particles[i].y + 0.5f, particles[i].z + zoom,particles[i].x - 0.5f, particles[i].y - 0.5f,particles[i].z + zoom };gl.glColor4f(particles[i].r, particles[i].g, particles[i].b,particles[i].life);vertexBuffer = formatFloatBuffer(temVectex);gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer);gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, temVectex.length / 3);particles[i].x += particles[i].xi / (slowdown * 10);particles[i].y += particles[i].yi / (slowdown * 10);particles[i].z += particles[i].zi / (slowdown * 10);particles[i].xi += particles[i].xg;particles[i].yi += particles[i].yg;particles[i].zi += particles[i].zg;particles[i].life -= particles[i].fade;if (particles[i].life < 0.0f) {particles[i].life = 1.0f;particles[i].fade = (float) (random.nextInt(100) % 100) / 1000.0f + 0.003f;particles[i].x = 0.0f;particles[i].y = 0.0f;particles[i].z = 0.0f;particles[i].xi = (float) ((random.nextInt(100) % 50) - 26.0f) * 10.0f;particles[i].yi = (float) ((random.nextInt(100) % 50) - 25.0f) * 10.0f;particles[i].zi = (float) ((random.nextInt(100) % 50) - 25.0f) * 10.0f;particles[i].xg = 0.0f;particles[i].yg = -0.8f;particles[i].zg = 0.0f;}}}}public void onDrawFrame(GL10 gl) {gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);gl.glLoadIdentity();gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);textureBuffer = formatFloatBuffer(textureCoordinate);gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);gl.glTranslatef(0.0f, 0.0f, -5.0f);drawParticle(gl);gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);}public void onSurfaceChanged(GL10 gl, int width, int height) {if (height == 0) {height = 1;}gl.glViewport(0, 0, width, height);gl.glMatrixMode(GL10.GL_PROJECTION);gl.glLoadIdentity();GLU.gluPerspective(gl, 45.0f, (float) width / (float) height, 0.1f,200.0f);gl.glMatrixMode(GL10.GL_MODELVIEW);gl.glLoadIdentity();}public void onSurfaceCreated(GL10 gl, EGLConfig config) {gl.glShadeModel(GL10.GL_SMOOTH);gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);gl.glClearDepthf(1.0f);gl.glDisable(GL10.GL_DEPTH_TEST);gl.glEnable(GL10.GL_BLEND);gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE);gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);gl.glEnable(GL10.GL_TEXTURE_2D);gl.glBindTexture(GL10.GL_TEXTURE_2D, texture[0]);loadTexture(gl, context);initParticals();}/** * the method is to load texture for the particle * */public void loadTexture(GL10 gl, Context context) {InputStream is = context.getResources().openRawResource(R.drawable.star);Bitmap bitmap = null;try {bitmap = BitmapFactory.decodeStream(is);} finally {try {is.close();is = null;} catch (IOException e) {e.printStackTrace();}}gl.glGenTextures(1, texture, 0);gl.glBindTexture(GL10.GL_TEXTURE_2D, texture[0]);gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,GL10.GL_LINEAR);gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER,GL10.GL_LINEAR);GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);bitmap.recycle();}/** * this is the particle class it has some attribute for each particle object * */class Particle {// We start off with the boolean variable active. If this variable is// TRUE, our particle is alive and kicking. If it's FALSE our particle// is dead or we've turned it off! In this program I don't use active,// but it's handy to include.// The variables life and fade control how long the particle is// displayed, and how bright the particle is while it's alive. The// variable life is gradually decreased by the value stored in fade. In// this program that will cause some particles to burn longer than// others.private boolean active;private float life;private float fade;// The variables r, g and b hold the red intensity, green intensity and// blue intensity of our particle. The closer r is to 1.0f, the more red// the particle will be. Making all 3 variables 1.0f will create a white// particle.private float r;private float g;private float b;// The variables x, y and z control where the particle will be displayed// on the screen. x holds the location of our particle on the x axis. y// holds the location of our particle on the y axis, and finally z holds// the location of our particle on the z axisprivate float x, y, z;// The next three variables are important. These three variables control// how fast a particle is moving on specific axis, and what direction to// move. If xi is a negative value our particle will move left. Positive// it will move right. If yi is negative our particle will move down.// Positive it will move up. Finally, if zi is negative the particle// will move into the screen, and postive it will move towards the// viewer.private float xi, yi, zi;// Lastly, 3 more variables! Each of these variables can be thought of// as gravity. If xg is a positive value, our particle will pull to the// right. If it's negative our particle will be pulled to the left. So// if our particle is moving left (negative) and we apply a positive// gravity, the speed will eventually slow so much that our particle// will start moving the opposite direction. yg pulls up or down and zg// pulls towards or away from the viewer.private float xg, yg, zg;}}

下面是运行OpenGL的activity，很简单的逻辑，但是必须重写onResume和onPause方法，并且调用GLSurfaceView的onResume和onPause方法(因为我们的MyRenderer类继承自GLSurfaceView类，所以也就是调用MyRenderer的)

public class TestActivity extends Activity {/** The OpenGL View */private MyRenderer glSurface;/** * Initiate the OpenGL View and set our own Renderer */@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);glSurface = new MyRenderer(this);setContentView(glSurface);}/** * Remember to resume the glSurface */@Overrideprotected void onResume() {super.onResume();glSurface.onResume();}/** * Also pause the glSurface */@Overrideprotected void onPause() {super.onPause();glSurface.onPause();}}

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