Allow sbbs to snap to the floor and ceiling (and also allow offsetting them)

assets/cubyz/biomes/silly.zig.zon

@@ -0,0 +1,27 @@
+.{
+	.properties = .{},
+	.minHeightLimit = 7,
+	.minHeight = 22,
+	.maxHeight = 40,
+	.maxHeightLimit = 50,
+	.smoothBeaches = true,
+	.minRadius = 256,
+	.maxRadius = 320,
+	.roughness = 1,
+	.hills = 5,
+	.chance = 100000,
+	.music = "cubyz:sunrise",
+	.validPlayerSpawn = true,
+	.ground_structure = .{
+		"cubyz:grass",
+		"2 to 3 cubyz:soil",
+	},
+	.structures = .{
+		.{
+			.id = "cubyz:sbb",
+			.structure = "cubyz:village/origin",
+			.placeMode = .all,
+			.chance = 0.0005,
+		},
+	},
+}

assets/cubyz/sbb/village/house/any.zig.zon

@@ -0,0 +1,7 @@
+.{
+	.blueprints = .{
+		.{.id = "cubyz:village/house/house", .chance = 0.2},
+		.{.id = null, .chance = 0.8},
+	},
+	.snapping = .bottom,
+}

assets/cubyz/sbb/village/origin.zig.zon

@@ -0,0 +1,9 @@
+.{
+	.blueprints = .{
+		.{.id = "cubyz:village/origin"},
+	},
+	.originOffset = .{0, 0, -1},
+	.children = .{
+		.green = "cubyz:village/path/always_path",
+	},
+}

assets/cubyz/sbb/village/path/always_path.zon

@@ -0,0 +1,11 @@
+.{
+	.blueprints = .{
+		.{.id = "cubyz:village/path/path_left", .chance = 0.5},
+		.{.id = "cubyz:village/path/path_right", .chance = 0.5},
+	},
+	.children = .{
+		.red = "cubyz:village/path/path_block",
+		.green = "cubyz:village/path/path",
+		.yellow = "cubyz:village/house/any",
+	},
+}

assets/cubyz/sbb/village/path/path.zig.zon

@@ -0,0 +1,12 @@
+.{
+	.blueprints = .{
+		.{.id = "cubyz:village/path/path_left", .chance = 0.35},
+		.{.id = "cubyz:village/path/path_right", .chance = 0.35},
+		.{.id = null, .chance = 0.3},
+	},
+	.children = .{
+		.red = "cubyz:village/path/path_block",
+		.green = "cubyz:village/path/path",
+		.yellow = "cubyz:village/house/any",
+	},
+}

assets/cubyz/sbb/village/path/path_block.zig.zon

@@ -0,0 +1,8 @@
+.{
+	.blueprints = .{
+		.{.id = "cubyz:village/path/path_block", .chance = 0.6},
+		.{.id = null, .chance = 0.4},
+	},
+	.snapping = .bottom,
+	.originOffset = .{0, 0, -1},
+}

src/server/terrain/simple_structures/SbbGen.zig

@@ -50,11 +50,11 @@ pub fn loadModel(arena: NeverFailingAllocator, parameters: ZonElement) *SbbGen {
 	return self;
 }
 
-pub fn generate(self: *SbbGen, _: GenerationMode, x: i32, y: i32, z: i32, chunk: *ServerChunk, _: CaveMapView, _: CaveBiomeMapView, seed: *u64, _: bool) void {
-	placeSbb(self, self.structureRef, Vec3i{x, y, z}, Neighbor.dirUp, self.rotation.getInitialRotation(seed), chunk, seed);
+pub fn generate(self: *SbbGen, _: GenerationMode, x: i32, y: i32, z: i32, chunk: *ServerChunk, caveMap: CaveMapView, _: CaveBiomeMapView, seed: *u64, _: bool) void {
+	placeSbb(self, self.structureRef, Vec3i{x, y, z}, Neighbor.dirUp, self.rotation.getInitialRotation(seed), chunk, caveMap, seed, 5);
 }
 
-fn placeSbb(self: *SbbGen, structure: *const sbb.StructureBuildingBlock, placementPosition: Vec3i, placementDirection: Neighbor, rotation: sbb.Rotation, chunk: *ServerChunk, seed: *u64) void {
+fn placeSbb(self: *SbbGen, structure: *const sbb.StructureBuildingBlock, placementPosition: Vec3i, placementDirection: Neighbor, rotation: sbb.Rotation, chunk: *ServerChunk, caveMap: CaveMapView, seed: *u64, iterationsLeft: usize) void {
 	const blueprints = &(structure.getBlueprints(seed).* orelse return);
 
 	const origin = blueprints[0].originBlock;
@@ -64,14 +64,41 @@ fn placeSbb(self: *SbbGen, structure: *const sbb.StructureBuildingBlock, placeme
 	});
 	const rotated = &blueprints[@intFromEnum(blueprintRotation)];
 	const rotatedOrigin = rotated.originBlock.pos();
-	const pastePosition = placementPosition - rotatedOrigin - placementDirection.relPos();
+	var pastePosition = placementPosition - rotatedOrigin - placementDirection.relPos();
+	pastePosition += structure.originOffset;
 
 	rotated.blueprint.pasteInGeneration(pastePosition, chunk, self.placeMode);
 
+	if(iterationsLeft == 0) return;
 	for(rotated.childBlocks) |childBlock| {
 		const child = structure.getChildStructure(childBlock) orelse continue;
 		const childRotation = rotation.getChildRotation(seed, child.rotation, childBlock.direction());
-		placeSbb(self, child, pastePosition + childBlock.pos(), childBlock.direction(), childRotation, chunk, seed);
+		var placementPos = pastePosition + childBlock.pos();
+		const oldZ = placementPos[2];
+		// std.debug.print("{d} {d}\n", .{placementPos[0], placementPos[1]});
+		if(placementPos[0] < 0 or placementPos[0] >= terrain.CaveMap.CaveMapFragment.width or placementPos[1] < 0 or placementPos[1] >= terrain.CaveMap.CaveMapFragment.width) {
+			return;
+		}
+		switch(child.snapping) {
+			.top => {
+				if(caveMap.isSolid(placementPos[0], placementPos[1], placementPos[2])) {
+					placementPos[2] = caveMap.findTerrainChangeBelow(placementPos[0], placementPos[1], placementPos[2]);
+				} else {
+					placementPos[2] = caveMap.findTerrainChangeAbove(placementPos[0], placementPos[1], placementPos[2]) + chunk.super.pos.voxelSize;
+				}
+				if(placementPos[2] & ~@as(i32, 31) != oldZ & ~@as(i32, 31)) return; // Too far from the surface.
+			},
+			.bottom => {
+				if(caveMap.isSolid(placementPos[0], placementPos[1], placementPos[2])) {
+					placementPos[2] = caveMap.findTerrainChangeAbove(placementPos[0], placementPos[1], placementPos[2]);
+				} else {
+					placementPos[2] = caveMap.findTerrainChangeBelow(placementPos[0], placementPos[1], placementPos[2]) + chunk.super.pos.voxelSize;
+				}
+				if(placementPos[2] & ~@as(i32, 31) != oldZ & ~@as(i32, 31)) return; // Too far from the surface.
+			},
+			.none => {},
+		}
+		placeSbb(self, child, placementPos, childBlock.direction(), childRotation, chunk, caveMap, seed, iterationsLeft - 1);
 	}
 }
 

src/server/terrain/structure_building_blocks.zig

@@ -77,9 +77,9 @@ const BlueprintEntry = struct {
 	childBlocks: []StructureBlock,
 
 	const StructureBlock = struct {
-		x: u16,
-		y: u16,
-		z: u16,
+		x: i16,
+		y: i16,
+		z: i16,
 		index: LocalBlockIndex,
 		data: u16,
 
@@ -225,11 +225,15 @@ pub const Rotation = union(RotationMode) {
 	}
 };
 
+const Snapping = enum {none, top, bottom};
+
 pub const StructureBuildingBlock = struct {
 	id: []const u8,
 	children: []?*StructureBuildingBlock,
 	blueprints: AliasTable(Blueprints),
 	rotation: Rotation,
+	snapping: Snapping,
+	originOffset: Vec3i,
 
 	fn initFromZon(stringId: []const u8, zon: ZonElement) !StructureBuildingBlock {
 		const zonBlueprintsList = zon.getChild("blueprints");
@@ -285,6 +289,8 @@ pub const StructureBuildingBlock = struct {
 			.children = arenaAllocator.alloc(?*StructureBuildingBlock, childBlockName.items.len),
 			.blueprints = .init(arenaAllocator, blueprintArray),
 			.rotation = rotation,
+			.snapping = std.meta.stringToEnum(Snapping, zon.get([]const u8, "snapping", "none")) orelse .none,
+			.originOffset = zon.get(Vec3i, "originOffset", .{0, 0, 0}),
 		};
 		@memset(self.children, null);