void FastTrailsApp::update()
{
// find out how many trails we should add
const double trails_per_second = 2000.0;
double elapsed = getElapsedSeconds() - mTime;
uint32_t num_trails = uint32_t(elapsed * trails_per_second);
// add this number of trails
// (note: it's an ugly function that draws a swirling trail around a sphere, just for demo purposes)
for(size_t i=0; i<num_trails; ++i ) {
float phi = mAngle * 0.01f;
float prev_phi = phi - 0.01f;
float theta = phi * 0.03f;
float prev_theta = prev_phi * 0.03f;
Vec3f pos = 45.0f * Vec3f( sinf( phi ) * cosf( theta ), sinf( phi ) * sinf( theta ), cosf( phi ) );
Vec3f prev_pos = 45.0f * Vec3f( sinf( prev_phi ) * cosf( prev_theta ), sinf( prev_phi ) * sinf( prev_theta ), cosf( prev_phi ) );
Vec3f direction = pos - prev_pos;
Vec3f right = Vec3f( sinf( 20.0f * phi ), 0.0f, cosf( 20.0f * phi ) );
Vec3f normal = direction.cross( right ).normalized();
// add two vertices, one at each side of the center line
mTrail.push_front( pos - 1.0f * normal );
mTrail.push_front( pos + 1.0f * normal );
mAngle += 1.0;
}
// keep trail length within bounds
while( mTrail.size() > TRAIL_LENGTH )
mTrail.pop_back();
// copy to trail to vbo (there's probably a faster way than this, need to check that out later)
gl::VboMesh::VertexIter itr = mVboMesh.mapVertexBuffer();
for( size_t i=0; i<mTrail.size(); ++i, ++itr )
itr.setPosition( mTrail[i] );
// advance time
mTime += num_trails / trails_per_second;
}
void FlockingParticlesApp::update() {
// update physics
timer->stop();
double dt = timer->getSeconds();
timer->start();
float mouseX = (float)getMousePos().x;
float mouseY = (float)getMousePos().y;
attractor->setPosition(Vec3f(mouseX, mouseY, 0));
physics->update(dt);
// copy particle positions into vbo
gl::VboMesh::VertexIter iter = vboParticles.mapVertexBuffer();
for(vector<Particle*>::iterator p = physics->particles.begin(); p != physics->particles.end(); p++) {
if(!(*p)->isAlive) continue;
iter.setPosition((*p)->position.x, (*p)->position.y, (*p)->position.z);
++iter;
}
}