From e6788d529a7817e161cd371ba1bcad231fe01d8d Mon Sep 17 00:00:00 2001
From: trafficlunar <hello@trafficlunar.net>
Date: Wed, 22 Jan 2025 22:03:58 +0000
Subject: [PATCH] fix: encode ids as varints when exporting .schem

---
 src/components/dialogs/SaveSchem.tsx | 16 ++++++++++++----
 src/utils/varint.ts                  |  9 +++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)
 create mode 100644 src/utils/varint.ts

diff --git a/src/components/dialogs/SaveSchem.tsx b/src/components/dialogs/SaveSchem.tsx
index 922f775..8e3a57d 100644
--- a/src/components/dialogs/SaveSchem.tsx
+++ b/src/components/dialogs/SaveSchem.tsx
@@ -4,6 +4,8 @@ import * as nbt from "nbtify";
 import { CanvasContext } from "@/context/Canvas";
 import { LoadingContext } from "@/context/Loading";
 
+import { encodeVarint } from "@/utils/varint";
+
 import { DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from "@/components/ui/dialog";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
@@ -103,10 +105,9 @@ function SaveLitematic({ close }: DialogProps) {
 		}, {});
 
 		// Get the block data
-		const buffer = new ArrayBuffer(filledBlocks.length);
-		const blockPlaceData = new Int8Array(buffer);
+		const ids: number[] = [];
 
-		filledBlocks.forEach((block, index) => {
+		filledBlocks.forEach((block) => {
 			const blockInfo = blockData[block.name.replace("minecraft:", "")];
 			const blockName = blockInfo ? blockInfo.id : block.name;
 			const properties = blockInfo.properties
@@ -116,9 +117,16 @@ function SaveLitematic({ close }: DialogProps) {
 				: "";
 			const blockId = blockPalette[`minecraft:${blockName}${properties}`];
 
-			blockPlaceData[index] = parseInt(blockId.toString());
+			// Parse blockId to number then encode as varint
+			const id = encodeVarint(parseInt(blockId.toString()));
+			// Push to separate array to make array buffer
+			ids.push(...id);
 		});
 
+		const buffer = new ArrayBuffer(ids.length);
+		const blockPlaceData = new Uint8Array(buffer);
+		blockPlaceData.set(ids);
+
 		// Generate NBT data
 		const data = {
 			Schematic: {
diff --git a/src/utils/varint.ts b/src/utils/varint.ts
new file mode 100644
index 0000000..27d5888
--- /dev/null
+++ b/src/utils/varint.ts
@@ -0,0 +1,9 @@
+export function encodeVarint(number: number) {
+	const result = [];
+	while (number >= 0x80) {
+		result.push((number & 0x7f) | 0x80); // Take 7 bits and set the MSB
+		number >>>= 7; // Right shift by 7 bits (logical shift)
+	}
+	result.push(number); // Last byte without MSB set
+	return new Uint8Array(result);
+}