From b16c0b64665350bc3f63108fd22d50bef714a2ec Mon Sep 17 00:00:00 2001
From: xtreme8000 <xtreme8000@users.noreply.github.com>
Date: Thu, 21 Nov 2019 18:03:20 +0100
Subject: [PATCH] Preserve existing blocks during linebuild

Close #93
---
 src/network.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/network.c b/src/network.c
index d33fae8..df242c4 100644
--- a/src/network.c
+++ b/src/network.c
@@ -246,10 +246,12 @@ void read_PacketBlockLine(void* data, int len) {
 		struct Point blocks[64];
 		int len = map_cube_line(p->sx,p->sy,p->sz,p->ex,p->ey,p->ez,blocks);
 		while(len>0) {
-			map_set(blocks[len-1].x,63-blocks[len-1].z,blocks[len-1].y,
-				players[p->player_id].block.red |
-				(players[p->player_id].block.green<<8) |
-				(players[p->player_id].block.blue<<16));
+			if(map_isair(blocks[len-1].x,63-blocks[len-1].z,blocks[len-1].y)) {
+				map_set(blocks[len-1].x,63-blocks[len-1].z,blocks[len-1].y,
+					players[p->player_id].block.red |
+					(players[p->player_id].block.green<<8) |
+					(players[p->player_id].block.blue<<16));
+			}
 			len--;
 		}
 	}