From 45b64a46ec51dbeb92c14366ad0bba013f4ec9b8 Mon Sep 17 00:00:00 2001
From: Sander Schobers <sander@schobers.eu>
Date: Mon, 9 Aug 2021 12:29:32 +0200
Subject: [PATCH] Added bias towards picking tiles further away (hearts/stars)
 or closer (monsters) when difficulty increases. Added minimum distance (from
 player) for spawning things.

---
 level.go | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/level.go b/level.go
index 6f816b3..017a602 100644
--- a/level.go
+++ b/level.go
@@ -2,6 +2,7 @@ package tins2021
 
 import (
 	"math/rand"
+	"sort"
 
 	"opslag.de/schobers/geom"
 )
@@ -126,14 +127,30 @@ func (l *Level) Randomize(difficulty int, stars int) {
 	for pos := range l.Tiles {
 		positions = append(positions, pos)
 	}
+	distances := l.Tiles.Distances(l.Player)
+	sort.Slice(positions, func(i, j int) bool {
+		return distances[positions[i]] < distances[positions[j]]
+	})
+	pick := func(bias int) geom.Point { // bias towards far away [0..100]
+		if bias > 100 {
+			bias = 100
+		}
+		if bias < 0 {
+			bias = 0
+		}
+		n := len(positions)
+		const min = 4
+		from := min + bias*(n-min)/(2*(n-min)) // never pick first
+		return positions[from+rand.Intn(n-from)]
+	}
+
 	flip := difficulty * len(l.Tiles) / 200
 	if flip > len(l.Tiles)/2 {
 		flip = len(l.Tiles) / 2
 	}
 	for ; flip > 0; flip-- {
 		for {
-			i := rand.Intn(len(positions))
-			pos := positions[i]
+			pos := pick(0)
 			if l.Tiles[pos].Inversed {
 				continue
 			}
@@ -146,8 +163,7 @@ func (l *Level) Randomize(difficulty int, stars int) {
 	}
 	l.Stars = stars
 	for stars > 0 {
-		i := rand.Intn(len(positions))
-		pos := positions[i]
+		pos := pick(difficulty)
 		if l.Tiles[pos].Occupied() {
 			continue
 		}
@@ -156,8 +172,7 @@ func (l *Level) Randomize(difficulty int, stars int) {
 	}
 	hearts := 1 + (100-difficulty)/50 // [3..1] (only difficulty has 3 hearts)
 	for hearts > 0 {
-		i := rand.Intn(len(positions))
-		pos := positions[i]
+		pos := pick(difficulty)
 		if l.Tiles[pos].Occupied() {
 			continue
 		}
@@ -168,8 +183,7 @@ func (l *Level) Randomize(difficulty int, stars int) {
 	minRandomMonster := (100-difficulty)*80/100 + 10 // [90..10]
 	minChaserMonster := (100-difficulty)*50/100 + 50 // [100..50]
 	for monsters > 0 {
-		i := rand.Intn(len(positions))
-		pos := positions[i]
+		pos := pick(100 - difficulty)
 		curr := l.Monsters[pos]
 		if l.Tiles[pos].Occupied() || curr != nil {
 			continue