使用OPenGL ES实现粒子发射器

粒子发射器

• 粒子发射器实现思路

  
  粒子发射器

使用粒子发射器

使用粒子发射器

• 示例代码

1. 设置Context

    self.mContext = [[EAGLContext alloc] initWithAPI:(kEAGLRenderingAPIOpenGLES3)];
    [EAGLContext setCurrentContext:self.mContext];
    GLKView *view = (GLKView *)self.view;
    view.context = self.mContext;
    view.drawableColorFormat = GLKViewDrawableColorFormatRGBA8888;
    view.drawableDepthFormat = GLKViewDrawableDepthFormat24;
    [EAGLContext setCurrentContext:self.mContext];

2. 加载纹理

    NSString *path = [[NSBundle bundleForClass:[self class]]
                      pathForResource:@"ball" ofType:@"png"];
    
    if (path == nil) {
        NSLog(@"ball texture image not found");
        return;
    }
    
    self.ballParticleTexture = [GLKTextureLoader textureWithContentsOfFile:path options:nil error:nil];
    
    self.particleEffect = [[XYPointParticleEffect alloc] init];
    self.particleEffect.texture2d0.name = self.ballParticleTexture.name;
    self.particleEffect.texture2d0.target = self.ballParticleTexture.target;

3. 设置渲染格式

    // 开启深度测试
    glEnable(GL_DEPTH_TEST);
    
    // 开启混合
    glEnable(GL_BLEND);
    
    // 设置混合模式
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

4. 设置添加粒子参数

void(^block)() = ^{
        
        self.autoSpawnDelta = 0.5f;
        
        //重力
        self.particleEffect.gravity = GLKVector3Make(0.0f, 0.0f, 0.0f);
        
        int n = 100;
        for(int i = 0; i < n; i++)
        {
            //X,Y,Z速度
            float randomXVelocity = -0.5f + 1.0f * (float)random() / (float)RAND_MAX;
            float randomYVelocity = -0.5f + 1.0f * (float)random() / (float)RAND_MAX;
            float randomZVelocity = -0.5f + 1.0f * (float)random() / (float)RAND_MAX;
            
            //创建粒子
            [self.particleEffect
             addParticleAtPosition:GLKVector3Make(0.0f, 0.0f, 0.0f)
             velocity:GLKVector3Make(
                                     randomXVelocity,
                                     randomYVelocity,
                                     randomZVelocity)
             force:GLKVector3Make(0.0f, 0.0f, 0.0f)
             size:4.0f
             lifeSpanSeconds:3.2f
             fadeDurationSeconds:0.5f];
        }
        
    };

5. 更新

- (void)update {
    
    NSTimeInterval timeElapsed = self.timeSinceFirstResume;
    
    self.particleEffect.elapsedSeconds = timeElapsed;
    
    if (self.autoSpawnDelta < (timeElapsed - self.lastSpawnTime)) {
        
        self.lastSpawnTime = timeElapsed;
        
        //执行block
        block();
    }
}

6. 绘制

- (void)glkView:(GLKView *)view drawInRect:(CGRect)rect {
    glClearColor(0.3, 0.3, 0.3, 1);
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
    
    
    //准备绘制
    [self.particleEffect prepareToDraw];
    
    //绘制
    [self.particleEffect draw];
}

Demo

Demo下载地址