number of particles to emit for a given rate

emit_parts.cpp

size_t EmitterNode::_numPartsForRate(float rate, float dt) {// number of parts to emit
    size_t numParts = 0;
    float numPartsReal = rate * dt;

    // Treat fractional particles as a probability -- e.g. .3 particles
    // means 30% chance to emit
    float numPartsF = floor(numPartsReal);
    float partProb = numPartsReal - numPartsF;
    numParts = (size_t)numPartsF;

    if (randUniform() < partProb)
    {
        numParts++;
    }
    return numParts;
}