chore: add comments to swarm.hpp

include/swarm.hpp

@@ -8,13 +8,37 @@
 #include <vec.hpp>
 #include <vector>
 
+/**
+ * An Agent in a Particle Swarm Optimisation simulation.
+ * #T is the type of the position vector the Agent uses.
+ */
 template<typename T>
 struct Agent {
+    /**
+     * Type of the fitness function.
+     */
     using F = std::function<float(T)>;
 
+    /**
+     * Moves the Agent along its velocity by a factor of #dt.
+     *
+     * The parameter #dt is useful when drawing the Agent moving faster than it
+     * #tick()s.
+     *
+     * @see: step()
+     */
     virtual void move(float dt) = 0;
+
+    /**
+     * Steps the algorithm values one tick forward.
+     * Warning: Does not move the Agent. Use #move() for this
+     * @see: move()
+     */
     virtual void step() = 0;
 
+    /**
+     * The best position this Agent has seen during its lifetime.
+     */
     virtual std::pair<float, T> best() const = 0;
 
     Agent(F f) : f(f) {}
@@ -24,6 +48,8 @@ protected:
 
 template <typename A>
 concept ParameterChangeAlgorithm = requires(A alg, float f, unsigned int i) {
+    // initial viscosity, initial nostalgia, initial peer pressure, current
+    // iteration, max iteration
     { alg(f, f, f, i, i) } -> std::same_as<vec<3>>;
 };
 
@@ -62,13 +88,14 @@ namespace ParamChange {
     };
 };
 
-template<std::size_t N, ParameterChangeAlgorithm A = ParamChange::MTanhAlg<>>
+template<std::size_t N, ParameterChangeAlgorithm A = ParamChange::MLinAlg>
 struct Particle : public Agent<vec<N>> {
     std::pair<float, vec<N>> best() const override { return {pb, pb_pos}; };
 
     void move(float dt=1) override { position = position + velocity * dt; }
 
     void step() override {
+	// Get the new parameter values
 	vec<3> params = alg(kviscosity, knostalgia, kpeer_pressure,
 			    curr_iter, max_iter);
 

src/main.cpp

@@ -65,12 +65,21 @@ main(int argc, char **argv) {
 	scr.draw();
     };
 
+    // We draw to the screen at a rate of `kFPS', but step()ing the swarm at
+    // this rate would be far too fast to be interesting to look at. On the
+    // other hand, step()ing once a second is too slow.
+    //
+    // So, we step() every quarter second. To line up the move() so that a unit
+    // move() happens preceding each step(), we also need to move as fast as
+    // we've shortened our step() interval.
     for(int i = 0; i < iter_count * kFPS/4;) {
 	if(!pause) {
 	    scr.clear();
 
 	    update_and_draw();
 
+	    // Since we step() 4x a second, we need to move() 4x as fast as moving by dt
+	    // each frame.
 	    swarm.move(kDT * 4);
 	    if(i % (kFPS/4) == (kFPS/4)-1)
 		swarm.step();
@@ -152,6 +161,7 @@ main(int argc, char **argv) {
 	    break;
 	}
 
+	// Wait for kDT (time between two frames)
 	usleep(1000 * 1000 / kFPS);
     }