From cc0fb04689ed71984458f542bc2154a5609ab95c Mon Sep 17 00:00:00 2001
From: hgn <hgodden00@gmail.com>
Date: Wed, 22 Sep 2021 14:32:04 +0100
Subject: [PATCH] [VID] flowing water

---
 fishladder.c | 67 ++++++++++++++++++++++++++++++++++------------------
 1 file changed, 44 insertions(+), 23 deletions(-)

diff --git a/fishladder.c b/fishladder.c
index b19f585..1934014 100644
--- a/fishladder.c
+++ b/fishladder.c
@@ -41,10 +41,12 @@ struct world
 	struct cell
 	{
 		u32 state;
-		u8 water;
+		u8 water[2];
 	}
 	*data;
 	
+	u32 frame;
+	
 	struct cell_terminal
 	{
 		char *conditions;
@@ -169,7 +171,8 @@ static int map_load( const char *str )
 			
 			// Tile initialization
 			// row[ cx ] .. etc
-			row[ cx ].water = 0;
+			row[ cx ].water[0] = 0;
+			row[ cx ].water[1] = 0;
 			
 			if( *c == '+' || *c == '-' )
 			{
@@ -296,35 +299,53 @@ void vg_update(void)
 	else
 		world.selected = -1;
 	
-	for( int y = 1; y < world.h-1; y ++ )
+	// Simulate world
+	static int update_tick = 0;
+	update_tick ++;
+	
+	if( update_tick > 5 )
 	{
-		for( int x = 1; x < world.w-1; x ++ )
+		update_tick = 0;
+		
+		u32 buffer_id = world.frame & 0x1;
+		u32 buffer_next = buffer_id ^ 0x1;
+		
+		for( int y = 1; y < world.h-1; y ++ )
 		{
-			struct cell *cell = &world.data[y*world.w+x];
-
-			if( !(cell->state & FLAG_CANAL) )
-				cell->water = 0;
-			
-			if( cell->state & FLAG_INPUT )
-				cell->water = 8;
-			
-			if( cell->water )
+			for( int x = 1; x < world.w-1; x ++ )
 			{
-				v2i dirs[] = {{1,0},{0,1},{-1,0},{0,-1}};
-				
-				for( int i = 0; i < vg_list_size( dirs ); i ++ )
+				struct cell *cell = &world.data[y*world.w+x];
+
+				if( cell->state & FLAG_INPUT )
+					cell->water[ buffer_next ] = 8;
+				else
 				{
-					struct cell *neighbour = &world.data[(y+dirs[i][1])*world.w+x+dirs[i][0]];
+					int has_source = 0;
+					cell->water[ buffer_next ] = 0;	
 					
-					if( neighbour->state & FLAG_CANAL )
+					if( cell->state & FLAG_CANAL )
 					{
-						neighbour->water = vg_max( neighbour->water, cell->water-1 );
+						v2i dirs[] = {{1,0},{0,1},{-1,0},{0,-1}};
+						
+						for( int i = 0; i < vg_list_size( dirs ); i ++ )
+						{
+							struct cell *neighbour = &world.data[(y+dirs[i][1])*world.w+x+dirs[i][0]];
+							
+							if( neighbour->water[ buffer_id ] > cell->water[ buffer_next ]+1 )
+							{
+								has_source = 1;
+								cell->water[ buffer_next ] = neighbour->water[ buffer_id ]-1;
+							}
+						}
 					}
+					
+					if( !has_source && cell->water[ buffer_id ] )
+						cell->water[ buffer_next ] = cell->water[ buffer_id ]-1;
 				}
-				
-				cell->water --;
 			}
 		}
+		
+		world.frame ++;
 	}
 }
 
@@ -356,8 +377,8 @@ void vg_render(void)
 			else if( cell->state & FLAG_OUTPUT ) { v4_copy( (v4f){ 0.2f, 0.7f, 0.3f, 1.0f }, colour ); }
 			else v4_copy( (v4f){ 0.9f, 0.9f, 0.9f, 1.0f }, colour );
 			
-			if( cell->water )
-				v4_copy( (v4f){ 0.2f, 0.3f, 0.7f * (float)(cell->water) * (1.0f/8.0f), 1.0f }, colour );
+			if( cell->water[world.frame&0x1] )
+				v4_copy( (v4f){ 0.2f, 0.3f, 0.7f * (float)(cell->water[world.frame&0x1]) * (1.0f/8.0f), 1.0f }, colour );
 			
 			if( world.selected == y*world.w + x )
 				v3_muls( colour, sinf( vg_time )*0.25f + 0.5f, colour );
-- 
2.25.1