From c11e23a18ff52db8c4f1dfe76c46fd26b92f71ef Mon Sep 17 00:00:00 2001
From: Aaron Griffith <aargri@gmail.com>
Date: Thu, 14 Oct 2010 13:57:48 -0400
Subject: [PATCH] added semi-correct lighting for half-blocks

---
 chunk.py | 38 +++++++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/chunk.py b/chunk.py
index 9cb5be2..67571f2 100644
--- a/chunk.py
+++ b/chunk.py
@@ -328,7 +328,7 @@ class ChunkRenderer(object):
             # Nighttime
             return 1.0 - pow(0.8, 15 - max(blocklight, skylight - 11))
     
-    def get_lighting_coefficient(self, x, y, z):
+    def get_lighting_coefficient(self, x, y, z, norecurse=False):
         """Calculates the lighting coefficient for the given
         coordinate, using default lighting and peeking into
         neighboring chunks, if needed. A lighting coefficient of 1.0
@@ -337,10 +337,7 @@ class ChunkRenderer(object):
         Returns a tuple (coefficient, occluded), where occluded is
         True if the given coordinate is filled with a solid block, and
         therefore the returned coefficient is just the default."""
-        
-        # fill it in with the default first (full skylight)
-        coefficient = self.calculate_darkness(15, 0)
-        
+                
         # placeholders for later data arrays, coordinates
         blocks = None
         skylight = None
@@ -373,13 +370,36 @@ class ChunkRenderer(object):
                 local_x >= 0 and local_x < 16 and local_y >= 0 and local_y < 16 and
                 local_z >= 0 and local_z < 128):
             # we have no useful info, return default
-            return (coefficient, False)
+            return (self.calculate_darkness(15, 0), False)
+        
+        # special handling for half-blocks
+        # (don't recurse more than once!)
+        if blocks[local_x, local_y, local_z] == 44 and not norecurse:
+            # average gathering variables
+            averagegather = 0.0
+            averagecount = 0
+            
+            # how bright we need before we consider a side "lit"
+            threshold = self.calculate_darkness(0, 0)
+            # iterate through all the sides of the block
+            sides = [(x-1, y, z), (x+1, y, z), (x, y, z-1), (x, y, z+1), (x, y-1, z), (x, y+1, z)]
+            
+            for side in sides:
+                val, occ = self.get_lighting_coefficient(*side, norecurse=True)
+                if (not occ) and (val < threshold):
+                    averagegather += val
+                    averagecount += 1
+            
+            # if at least one side was lit, return the average
+            if averagecount > 0:
+                return (averagegather / averagecount, False)
         
         # calculate the return...
         occluded = not (blocks[local_x, local_y, local_z] in transparent_blocks)
-        
-        # only calculate the coefficient if we're not occluded
-        if not occluded:
+        # only calculate the non-default coefficient if we're not occluded
+        if occluded:
+            coefficient = self.calculate_darkness(15, 0)
+        else:
             coefficient = self.calculate_darkness(skylight[local_x, local_y, local_z], blocklight[local_x, local_y, local_z])
         
         # only say we're occluded if the point is in the CURRENT