Clean up FlowField

Author: w2sv

app/src/main/java/com/w2sv/autocrop/flowfield/FlowField.java

@@ -2,41 +2,44 @@
 
 import android.util.Pair;
 
-import androidx.annotation.NonNull;
-
-import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.Iterator;
 import java.util.Map;
 
 import processing.core.PApplet;
 import processing.core.PVector;
 
 class FlowField {
     private static final Map<Pair<Integer, Integer>, Float> xOffCache = new HashMap<>();
-    private float zOff = 0;
 
-    void update(ArrayList<Particle> particles, PApplet parent) {
-        var pos2Noise = new HashMap<Pair<Integer, Integer>, PVector>();
+    private float zOff = 0;
 
-        for (int i = 0; i < particles.size(); i++) {
-            var pos = new Pair<>(
-                    PApplet.floor(particles.get(i).pos.x / Sketch.Config.FLOW_FIELD_GRANULARITY) + 1,
-                    PApplet.floor(particles.get(i).pos.y / Sketch.Config.FLOW_FIELD_GRANULARITY) + 1
-            );
+    void updateAndApplyTo(Iterator<Particle> particles, PApplet parent) {
+        HashMap<Pair<Integer, Integer>, PVector> forceCash = new HashMap<>();
 
-            if (pos2Noise.containsKey(pos))
-                particles.get(i).applyFlowFieldVector(pos2Noise.get(pos));
-            else {
-                PVector v = PVector.fromAngle(parent.noise(xOff(pos), 0, zOff) * 25.132742f).normalize();
-                particles.get(i).applyFlowFieldVector(v);
-                pos2Noise.put(pos, v);
-            }
-        }
+        particles.forEachRemaining((particle -> particle.applyForceVector(
+                getForceVector(
+                        Pair.create(
+                                PApplet.floor(particle.pos.x / Sketch.Config.FLOW_FIELD_GRANULARITY) + 1,
+                                PApplet.floor(particle.pos.y / Sketch.Config.FLOW_FIELD_GRANULARITY) + 1
+                        ),
+                        forceCash,
+                        parent
+                )
+        )));
 
         zOff += Sketch.Config.FLOW_FIELD_Z_OFF_INCREMENT;
     }
 
-    private float xOff(@NonNull Pair<Integer, Integer> pos) {
+    private PVector getForceVector(Pair<Integer, Integer> pos, HashMap<Pair<Integer, Integer>, PVector> forceCash, PApplet parent) {
+        if (forceCash.containsKey(pos))
+            return forceCash.get(pos);
+        PVector v = PVector.fromAngle(parent.noise(getXOff(pos), 0, zOff) * 25.132742f).normalize();
+        forceCash.put(pos, v);
+        return v;
+    }
+
+    private float getXOff(Pair<Integer, Integer> pos) {
         if (xOffCache.containsKey(pos))
             //noinspection ConstantConditions
             return xOffCache.get(pos);

app/src/main/java/com/w2sv/autocrop/flowfield/Particle.java

@@ -42,7 +42,7 @@ public Particle(PApplet parent) {
         previousPos = pos.copy();
     }
 
-    void applyFlowFieldVector(PVector v) {
+    void applyForceVector(PVector v) {
         acc = v;
     }
 

app/src/main/java/com/w2sv/autocrop/flowfield/Sketch.java

@@ -30,6 +30,7 @@ static class Config{
                 0xFF6B13B5,  // purple
                 0xFF1a0ac7   // ocean blue
         );
+        static final int BACKGROUND_COLOR = 0;
         static final int FLOW_FIELD_GRANULARITY = 200;
         static final float FLOW_FIELD_Z_OFF_INCREMENT = 0.004f;
     }
@@ -53,7 +54,7 @@ public void setup() {
         // enable 120fps for devices being capable of it; Otherwise the fps produced by the sketch will
         // accommodate the hardware-determined limit
         frameRate(120);
-        background(0);
+        background(Config.BACKGROUND_COLOR);
 
         // initialize particles
         Particle.setFlowFieldDimensions(width, height);
@@ -65,7 +66,7 @@ public void setup() {
 
     @Override
     public void draw() {
-        flowfield.update(particles, this);
+        flowfield.updateAndApplyTo(particles.iterator(), this);
 
         alphaDropper.dropAlphaIfDue(millis(), g);
         Particle.colorHandler.changeColorIfDue(millis(), g);