add an ability to change goids amount

config.yaml

@@ -1,6 +1,19 @@
+- step: 10
+  amount: 100
+  neighbours: 10
 - step: 100
   amount: 100
+  neighbours: 50
 - step: 200
   amount: 150
+  neighbours: 20
 - step: 300
   amount: 40
+  neighbours: 10
+- step: 400
+  amount: 10
+  neighbours: 5
+- step: 500
+  amount: 1
+  neighbours: 1
+

main.go

@@ -18,28 +18,30 @@ import (
 )
 
 // parameters
-var windowWidth, windowHeight = 800, 600
+var windowWidth, windowHeight = 1000, 700
 var goidSize = 3
 var goidColor = color.RGBA{200, 200, 100, 255} // gray, 50% transparency
-var populationSize = 10
-var loops = 10000
+var populationSize = 20
+var loops = 500
 var numNeighbours = 10
 var separationFactor = float64(goidSize * 5)
 var coherenceFactor = 8
 
 type steps struct {
-	Step int `yaml:"step"` 
+	Step   int `yaml:"step"`
 	Amount int `yaml:"amount"`
+	NumNeighbours int `yaml:"neighbours"`
 }
 
-func fixGoids(goids &[]*Goid, actual int, wished int) {
+func fixGoids(gs []*Goid, actual int, wished int) ([]*Goid, int) {
 	if actual < wished {
 		g := createRandomGoid()
-		goids = append(&goids, &g)
+		gs = append(gs, &g)
+		return gs, actual + 1
 	} else if wished < actual {
-    fmt.Println("it's not supported yet")
+		return gs[:len(gs)-1], actual -1
 	} else {
-		return
+		return gs, actual
 	}
 }
 
@@ -48,7 +50,7 @@ func main() {
 	if err != nil {
 		panic(err)
 	}
-  conf, err := ioutil.ReadFile("config.yaml")
+	conf, err := ioutil.ReadFile("config.yaml")
 	if err != nil {
 		panic(err)
 	}
@@ -71,11 +73,9 @@ func main() {
 	current_stage := 0
 
 	for i := 0; i < loops; i++ {
-		if i < td[current_stage].Step {
-			fmt.Printf("%d -- %d -- %d", i, current_stage, td[current_stage].Amount )
-			populationSize = td[current_stage].Amount
-		} else {
-			fixGoids(goids, populationSize, td[current_stage].Amount)
+		goids, populationSize = fixGoids(goids, populationSize, td[current_stage].Amount)
+		numNeighbours = td[current_stage].NumNeighbours
+		if i > td[current_stage].Step {
 			current_stage += 1
 		}
 		move(goids, fo)
@@ -95,7 +95,6 @@ type Goid struct {
 	Color color.Color
 }
 
-
 func createRandomGoid() (g Goid) {
 	g = Goid{
 		X:     rand.Intn(windowWidth),