Building a particle system on Android

Particle systems are widely used in games. Explosions, snow and smoke for example are created by particle system in most of today's games. What I wanna do in this post is to show you how to build an extensible OpenGL ES 2.0 particle system for Android.
To make it extensible, maybe we need add a script support for the particle system. But considering it's not a easy job writing a perfect script parser and running a script may decrease the frame rates significantly( anyway android devices are not PCs), so my solution is writing a virtual base class that contains basic particle methods and then overload these methods with specific particle effects.

Explosion Particle in Happy Fruit 3D

My base class in this post is not virtual nor doing noting, it is rendering Explosions.

First let's see how to initialize the system:

void Particle::init()
{
	char gVertexShader[] =
		  "uniform mat4 u_mvpMatrix;                            \n"
	      "uniform float u_time;		                        \n"
	      "uniform vec3 u_centerPosition;                       \n"
	      "attribute float a_lifetime;                          \n"
	      "attribute vec3 a_startPosition;                      \n"
	      "attribute vec3 a_endPosition;                        \n"
	      "varying float v_lifetime;                            \n"
	      "void main()                                          \n"
	      "{                                                    \n"
	      "  if ( u_time <= a_lifetime )                        \n"
	      "  {                                                  \n"
	      "    gl_Position.xyz = a_startPosition + 				\n"
	      "                      (u_time * a_endPosition);   	\n"
		  "    gl_Position=(u_mvpMatrix*gl_Position);			\n"
	      "  }                                                  \n"
	      "  v_lifetime = 1.0 - ( u_time / a_lifetime );        \n"
	      "  v_lifetime = clamp ( v_lifetime, 0.0, 1.0 );       \n"
	      "  gl_PointSize =sin( v_lifetime*v_lifetime *3.1416 ) \n"
		  "						* 80.0; 						\n"
	      "}";

	char gFragmentShader[] =
	      "precision mediump float;                             \n"
	      "uniform vec4 u_color;		                        \n"
	      "varying float v_lifetime;                            \n"
	      "uniform sampler2D s_texture;                         \n"
	      "void main()                                          \n"
	      "{                                                    \n"
	      "  vec4 texColor;                                     \n"
	      "  texColor = texture2D( s_texture, gl_PointCoord );  \n"
	      "  gl_FragColor =  texColor;      					\n"
	      "  gl_FragColor.a *= (v_lifetime);}					\n";

	if(gFragmentShader!=0 && gVertexShader!=0)
	{
		gProgram = createProgram(gVertexShader, gFragmentShader);
	}
	if (!gProgram)
	{
		LOGE("Could not create program for particle.");
		return;
	}
	LOGI("particle program ok");