From 662ef94d0c5593e83dedfe422930364cf5853afc Mon Sep 17 00:00:00 2001
From: IntegratedQuantum <jahe788@gmail.com>
Date: Mon, 25 Mar 2024 20:55:31 +0100
Subject: [PATCH] Add a terrain border between caves and the ocean floor.

Fixes #282
Also fixes #281 by making water degradable
---
 assets/cubyz/blocks/water.json                |  1 +
 src/server/terrain/CaveBiomeMap.zig           | 20 ++++++++------
 src/server/terrain/CaveMap.zig                |  2 +-
 .../terrain/cavegen/SurfaceGenerator.zig      | 26 ++++++++++++++-----
 4 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/assets/cubyz/blocks/water.json b/assets/cubyz/blocks/water.json
index 132b41d2..6aed13d8 100644
--- a/assets/cubyz/blocks/water.json
+++ b/assets/cubyz/blocks/water.json
@@ -5,6 +5,7 @@
 	],
 	"selectable" : false,
 	"solid" : false,
+	"degradable" : true,
 	"transparent" : true,
 	"hasBackFace" : true,
 	"absorbedLight" : 0x090501,
diff --git a/src/server/terrain/CaveBiomeMap.zig b/src/server/terrain/CaveBiomeMap.zig
index 855c64aa..925bb0e9 100644
--- a/src/server/terrain/CaveBiomeMap.zig
+++ b/src/server/terrain/CaveBiomeMap.zig
@@ -301,6 +301,17 @@ pub const InterpolatableCaveBiomeMapView = struct {
 		return self.surfaceFragments[index].getBiome(wx, wy);
 	}
 
+	pub fn getSurfaceHeight(self: InterpolatableCaveBiomeMapView, wx: i32, wy: i32) f32 {
+		var index: u8 = 0;
+		if(wx - self.surfaceFragments[0].pos.wx >= MapFragment.mapSize*self.pos.voxelSize) {
+			index += 2;
+		}
+		if(wy - self.surfaceFragments[0].pos.wy >= MapFragment.mapSize*self.pos.voxelSize) {
+			index += 1;
+		}
+		return self.surfaceFragments[index].getHeight(wx, wy);
+	}
+
 	noinline fn _getBiome(self: InterpolatableCaveBiomeMapView, wx: i32, wy: i32, wz: i32, map: u1) *const Biome {
 		var index: u8 = 0;
 		if(wx - self.fragments[0].pos.wx >= CaveBiomeMapFragment.caveBiomeMapSize) {
@@ -388,14 +399,7 @@ pub const CaveBiomeMapView = struct {
 	}
 
 	pub fn getSurfaceHeight(self: CaveBiomeMapView, wx: i32, wy: i32) f32 {
-		var index: u8 = 0;
-		if(wx - self.super.surfaceFragments[0].pos.wx >= MapFragment.mapSize*self.super.pos.voxelSize) {
-			index += 2;
-		}
-		if(wy - self.super.surfaceFragments[0].pos.wy >= MapFragment.mapSize*self.super.pos.voxelSize) {
-			index += 1;
-		}
-		return self.super.surfaceFragments[index].getHeight(wx, wy);
+		return self.super.getSurfaceHeight(wx, wy);
 	}
 
 	pub fn getBiome(self: CaveBiomeMapView, relX: i32, relY: i32, relZ: i32) *const Biome {
diff --git a/src/server/terrain/CaveMap.zig b/src/server/terrain/CaveMap.zig
index 904a9710..b3c2b840 100644
--- a/src/server/terrain/CaveMap.zig
+++ b/src/server/terrain/CaveMap.zig
@@ -32,7 +32,7 @@ pub const CaveMapFragment = struct {
 			},
 			.voxelShift = @ctz(voxelSize),
 		};
-		@memset(&self.data, 0);
+		@memset(&self.data, std.math.maxInt(u64));
 	}
 
 	fn getIndex(x: i32, y: i32) usize {
diff --git a/src/server/terrain/cavegen/SurfaceGenerator.zig b/src/server/terrain/cavegen/SurfaceGenerator.zig
index 7af2f89f..6b094215 100644
--- a/src/server/terrain/cavegen/SurfaceGenerator.zig
+++ b/src/server/terrain/cavegen/SurfaceGenerator.zig
@@ -8,6 +8,7 @@ const terrain = main.server.terrain;
 const CaveMapFragment = terrain.CaveMap.CaveMapFragment;
 const SurfaceMap = terrain.SurfaceMap;
 const MapFragment = SurfaceMap.MapFragment;
+const InterpolatableCaveBiomeMapView = terrain.CaveBiomeMap.InterpolatableCaveBiomeMapView;
 const vec = main.vec;
 const Vec3d = vec.Vec3d;
 const Vec3f = vec.Vec3f;
@@ -15,7 +16,7 @@ const Vec3i = vec.Vec3i;
 
 pub const id = "cubyz:surface";
 
-pub const priority = 1024;
+pub const priority = 131072;
 
 pub const generatorSeed = 0x7658930674389;
 
@@ -29,13 +30,26 @@ pub fn deinit() void {
 
 pub fn generate(map: *CaveMapFragment, worldSeed: u64) void {
 	_ = worldSeed;
-	const mapFragment = SurfaceMap.getOrGenerateFragment(map.pos.wx, map.pos.wy, map.pos.voxelSize);
-	defer mapFragment.deinit();
+	const width = CaveMapFragment.width*map.pos.voxelSize;
+	const biomeMap = InterpolatableCaveBiomeMapView.init(map.pos, width);
+	defer biomeMap.deinit();
 	var x: u31 = 0;
-	while(x < CaveMapFragment.width*map.pos.voxelSize) : (x += map.pos.voxelSize) {
+	while(x < width) : (x += map.pos.voxelSize) {
 		var y: u31 = 0;
-		while(y < CaveMapFragment.width*map.pos.voxelSize) : (y += map.pos.voxelSize) {
-			map.addRange(x, y, 0, @as(i32, @intFromFloat(mapFragment.getHeight(map.pos.wx + x, map.pos.wy + y))) - map.pos.wz);
+		while(y < width) : (y += map.pos.voxelSize) {
+			const height = biomeMap.getSurfaceHeight(map.pos.wx + x, map.pos.wy + y);
+			const smallestHeight: i32 = @intFromFloat(@floor(@min(
+				biomeMap.getSurfaceHeight(map.pos.wx + x + 1, map.pos.wy + y),
+				biomeMap.getSurfaceHeight(map.pos.wx + x, map.pos.wy + y + 1),
+				biomeMap.getSurfaceHeight(map.pos.wx + x - 1, map.pos.wy + y),
+				biomeMap.getSurfaceHeight(map.pos.wx + x, map.pos.wy + y - 1),
+				height,
+			) - 0.5));
+			const relativeHeight: i32 = @as(i32, @intFromFloat(height)) - map.pos.wz;
+			map.removeRange(x, y, relativeHeight, CaveMapFragment.height*map.pos.voxelSize);
+			if(smallestHeight < 1) { // Seal off caves that intersect the ocean floor.
+				map.addRange(x, y, smallestHeight -% 1 -% map.pos.wz, relativeHeight);
+			}
 		}
 	}
 }