From 56496ad5d8a7662b0ae5c9f25d1348cb7b677b65 Mon Sep 17 00:00:00 2001
From: Perttu Ahola <celeron55@gmail.com>
Date: Fri, 27 Jan 2012 12:58:52 +0200
Subject: Implement propagateSunlight for VoxelManipulator

---
 src/voxelalgorithms.cpp | 126 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 src/voxelalgorithms.cpp

(limited to 'src/voxelalgorithms.cpp')

diff --git a/src/voxelalgorithms.cpp b/src/voxelalgorithms.cpp
new file mode 100644
index 000000000..ae609e96a
--- /dev/null
+++ b/src/voxelalgorithms.cpp
@@ -0,0 +1,126 @@
+/*
+Minetest-c55
+Copyright (C) 2010-2012 celeron55, Perttu Ahola <celeron55@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "voxelalgorithms.h"
+#include "nodedef.h"
+
+namespace voxalgo
+{
+
+void setLight(VoxelManipulator &v, VoxelArea a, u8 light,
+		INodeDefManager *ndef)
+{
+	for(s32 x=a.MinEdge.X; x<=a.MaxEdge.X; x++)
+	for(s32 z=a.MinEdge.Z; z<=a.MaxEdge.Z; z++)
+	for(s32 y=a.MinEdge.Y; y<=a.MaxEdge.Y; y++)
+	{
+		v3s16 p(x,y,z);
+		MapNode &n = v.getNodeRefUnsafe(p);
+		n.setLight(LIGHTBANK_DAY, light, ndef);
+		n.setLight(LIGHTBANK_NIGHT, light, ndef);
+	}
+}
+
+SunlightPropagateResult propagateSunlight(VoxelManipulator &v, VoxelArea a,
+		bool inexistent_top_provides_sunlight,
+		core::map<v3s16, bool> & light_sources,
+		INodeDefManager *ndef)
+{
+	// Return values
+	bool bottom_sunlight_valid = true;
+
+	// The full area we shall touch extends one extra at top and bottom
+	VoxelArea required_a = a;
+	required_a.pad(v3s16(0,1,0));
+	// Make sure we have access to it
+	v.emerge(a);
+	
+	s16 max_y = a.MaxEdge.Y;
+	s16 min_y = a.MinEdge.Y;
+	
+	for(s32 x=a.MinEdge.X; x<=a.MaxEdge.X; x++)
+	for(s32 z=a.MinEdge.Z; z<=a.MaxEdge.Z; z++)
+	{
+		v3s16 p_overtop(x, max_y+1, z);
+		bool overtop_has_sunlight = false;
+		// If overtop node does not exist, trust heuristics
+		if(!v.exists(p_overtop))
+			overtop_has_sunlight = inexistent_top_provides_sunlight;
+		else if(v.getNodeRefUnsafe(p_overtop).getContent() == CONTENT_IGNORE)
+			overtop_has_sunlight = inexistent_top_provides_sunlight;
+		// Otherwise refer to it's light value
+		else
+			overtop_has_sunlight = (v.getNodeRefUnsafe(p_overtop).getLight(
+					LIGHTBANK_DAY, ndef) == LIGHT_SUN);
+
+		dstream<<"inexistent_top_provides_sunlight="
+				<<inexistent_top_provides_sunlight<<std::endl;
+		dstream<<"v.exists(p_overtop)="
+				<<v.exists(p_overtop)<<std::endl;
+
+		// Copy overtop's sunlight all over the place
+		u8 incoming_light = overtop_has_sunlight ? LIGHT_SUN : 0;
+		for(s32 y=max_y; y>=min_y; y--)
+		{
+			v3s16 p(x,y,z);
+			MapNode &n = v.getNodeRefUnsafe(p);
+			if(incoming_light == 0){
+				// Do nothing
+			} else if(incoming_light == LIGHT_SUN &&
+					ndef->get(n).sunlight_propagates){
+				// Do nothing
+			} else if(ndef->get(n).sunlight_propagates == false){
+				incoming_light = 0;
+			} else {
+				incoming_light = diminish_light(incoming_light);
+			}
+			u8 old_light = n.getLight(LIGHTBANK_DAY, ndef);
+
+			if(incoming_light > old_light)
+				n.setLight(LIGHTBANK_DAY, incoming_light, ndef);
+			
+			if(diminish_light(incoming_light) != 0)
+				light_sources.insert(p, true);
+		}
+		
+		// Check validity of sunlight at top of block below if it
+		// hasn't already been proven invalid
+		if(bottom_sunlight_valid)
+		{
+			bool sunlight_should_continue_down = (incoming_light == LIGHT_SUN);
+			v3s16 p_overbottom(x, min_y-1, z);
+			if(!v.exists(p_overbottom) ||
+					v.getNodeRefUnsafe(p_overbottom
+							).getContent() == CONTENT_IGNORE){
+				// Is not known, cannot compare
+			} else {
+				bool overbottom_has_sunlight = (v.getNodeRefUnsafe(p_overbottom
+						).getLight(LIGHTBANK_DAY, ndef) == LIGHT_SUN);
+				if(sunlight_should_continue_down != overbottom_has_sunlight){
+					bottom_sunlight_valid = false;
+				}
+			}
+		}
+	}
+
+	return SunlightPropagateResult(bottom_sunlight_valid);
+}
+
+} // namespace voxalgo
+
-- 
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