comparison CollidoscopeApp/src/ParticleController.cpp @ 4:ab6db404403a

commented JackDevice

 
 ParticleController::ParticleController() :
 mNumParticles( 0 )
 
 {
+    // uses Cinder (and OpenGL) virtual buffer object based drawing
+    // see ParticleSphereCPU example in Cinder library 
+     
     mParticles.assign( kMaxParticles, Particle() );
     mParticlePositions.assign( kMaxParticles, vec2( -1, -1 ) );
 
     mParticleVbo = gl::Vbo::create( GL_ARRAY_BUFFER, mParticlePositions, GL_DYNAMIC_DRAW );
 
     geom::BufferLayout particleLayout;
     particleLayout.append( geom::Attrib::POSITION, 2, sizeof( vec2 ), 0 );
 
     auto mesh = gl::VboMesh::create( mParticlePositions.size(), GL_POINTS, { { particleLayout, mParticleVbo } } );
 
+    // creates glsl program to run the batch with 
 #if ! defined( CINDER_GL_ES )
     auto glsl = gl::GlslProg::create( gl::GlslProg::Format()
         .vertex( CI_GLSL( 150,
             uniform mat4	ciModelViewProjection;
             in vec4			ciPosition;

 
 }
 
 void ParticleController::updateParticles()
 {
+    // update the positions of the particles and dispose them if they're reached their timespan
     for ( size_t i = 0; i < mNumParticles; i++ ){
 
         Particle &particle = mParticles[i];
         vec2 &pos = mParticlePositions[i];
 

         if ( ci::distance( pos, particle.mCloudCenter ) >  particle.mCloudSize && !particle.mFlyOver ){
             particle.mVel = rotate<float>( particle.mVel, 5 );
         }
     }
 
+    // Copy particle data onto the GPU.
+	// Map the GPU memory and write over it.
     void *gpuMem = mParticleVbo->mapReplace();
     memcpy( gpuMem, mParticlePositions.data(), mParticlePositions.size() * sizeof( vec2 ) );
     mParticleVbo->unmap();
 }
 
 void ParticleController::addParticles(int amount, const vec2 &initialLocation, const float cloudSize)
 {
+    // reduce the particles liearly to the total number of particles already present 
+    // the more particles aleary present the less particle are added
     int reduction = ci::lmap<int>(mNumParticles, 0, kMaxParticles, 0, kMaxParticleAdd);
     amount -= reduction;
 
     if ( mNumParticles + amount > kMaxParticles ){
-		//return;
+		//a.k.a. return if reached kMaxParticles 
         amount = kMaxParticles - mNumParticles;
 	}
 
     if( amount <= 0 )
         return;