From 5633ec9cdd957384cbb788d05bdd758074dc6f59 Mon Sep 17 00:00:00 2001
From: dags- <dags@dags.me>
Date: Fri, 6 Mar 2020 20:50:57 +0000
Subject: [PATCH] Make sure connecting rivers aren't wider than the river
 they're connecting to at the point of connection

---
 .../terraforged/core/world/river/River.java   |  2 ++
 .../core/world/river/RiverConfig.java         | 30 +++++++++++++++++++
 .../core/world/river/RiverRegion.java         | 12 +++++---
 3 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/TerraForgedCore/src/main/java/com/terraforged/core/world/river/River.java b/TerraForgedCore/src/main/java/com/terraforged/core/world/river/River.java
index 610a3a2..3632e75 100644
--- a/TerraForgedCore/src/main/java/com/terraforged/core/world/river/River.java
+++ b/TerraForgedCore/src/main/java/com/terraforged/core/world/river/River.java
@@ -54,6 +54,7 @@ public class River extends TerrainPopulator {
     private final Line bed;
     private final Line banks;
     private final Line valley;
+    public final RiverConfig config;
     public final RiverBounds bounds;
 
     private final Terrains terrains;
@@ -72,6 +73,7 @@ public class River extends TerrainPopulator {
         Module bankWidth = Source.constant(config.bankWidth * config.bankWidth);
         Module valleyWidth = Source.constant(VALLEY_WIDTH * VALLEY_WIDTH);
         this.bounds = bounds;
+        this.config = config;
         this.main = config.main;
         this.terrains = terrains;
         this.connecting = connecting;
diff --git a/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverConfig.java b/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverConfig.java
index d893be3..0f7a2ed 100644
--- a/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverConfig.java
+++ b/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverConfig.java
@@ -26,6 +26,7 @@
 package com.terraforged.core.world.river;
 
 import com.terraforged.core.world.heightmap.Levels;
+import me.dags.noise.util.NoiseUtil;
 
 public class RiverConfig {
 
@@ -49,6 +50,35 @@ public class RiverConfig {
         fade = builder.fade;
     }
 
+    private RiverConfig(boolean main, int bedWidth, int bankWidth, float bedHeight, float minBankHeight, float maxBankHeight, int length2, double fade) {
+        this.main = main;
+        this.bedWidth = bedWidth;
+        this.bankWidth = bankWidth;
+        this.bedHeight = bedHeight;
+        this.minBankHeight = minBankHeight;
+        this.maxBankHeight = maxBankHeight;
+        this.length2 = length2;
+        this.fade = fade;
+    }
+
+    public RiverConfig createFork(float connectWidth) {
+        if (bankWidth < connectWidth) {
+            return this;
+        }
+
+        float scale = bankWidth / connectWidth;
+        return new RiverConfig(
+                false,
+                NoiseUtil.round(bedWidth / scale),
+                NoiseUtil.round(bankWidth / scale),
+                bedHeight,
+                minBankHeight,
+                maxBankHeight,
+                length2,
+                fade
+        );
+    }
+
     public static Builder builder(Levels levels) {
         return new Builder(levels);
     }
diff --git a/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverRegion.java b/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverRegion.java
index f88949e..718c302 100644
--- a/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverRegion.java
+++ b/TerraForgedCore/src/main/java/com/terraforged/core/world/river/RiverRegion.java
@@ -95,15 +95,15 @@ public class RiverRegion {
             generateRiver(x, z, pos, primary, random, rivers);
         }
 
-        for (int i = 0; rivers.size() < 10 && i < 50; i++) {
+        for (int i = 0; rivers.size() < 15 && i < 100; i++) {
             generateRiver(x, z, pos, secondary, random, rivers);
         }
 
-        for (int i = 0; rivers.size() < 20 && i < 50; i++) {
+        for (int i = 0; rivers.size() < 25 && i < 75; i++) {
             generateRiverFork(x, z, pos, tertiary, random, rivers);
         }
 
-        for (int i = 0; rivers.size() < 30 && i < 50; i++) {
+        for (int i = 0; rivers.size() < 40 && i < 50; i++) {
             generateRiver(x, z, pos, tertiary, random, rivers);
         }
 
@@ -211,7 +211,11 @@ public class RiverRegion {
 
         generateLake(bounds, random);
 
-        return rivers.add(new River(bounds, config, terrains, config.fade, 0, true));
+        // scale the connecting river's width down so that it's narrower than the one it's connecting to
+        float forkWidth = closest.config.bankWidth * distance * 0.6F;
+        RiverConfig forkConfig = config.createFork(forkWidth);
+        
+        return rivers.add(new River(bounds, forkConfig, terrains, forkConfig.fade, 0, true));
     }
 
     private void generateLake(RiverBounds bounds, Random random) {