python image handling

README.md

@@ -49,7 +49,7 @@ which means that values from 10-19 are equivalent to 1, 20-29 are equivalent to
 The biome file is assumed to be 8-bit. pixel values that equate to 1 (or 10-19) will paint as roads, and pixel values that equate to biome 5 () will paint as water.
 A color image can be used for elevation and landcover but only the red channel is used.
 Read the defaults to see what the other biomes equate to in the USGS system, or redefine them in the in-game biome settings tool.
-Using a graphics editor that doesn't do anti-aliasing and preserves exact red channel values is recommended.
+Using a graphics editor that doesn't do anti-aliasing and preserves exact red channel values is recommended. Also if using the experimental python image handling, greyscale is required.
 - OR download DEM and USGS landcover/landuse tiles for same the same extent. Note, for true 16-bit DEMs you must use magick, not imlib2
 - after you change settings exit the world and delete the map.sqlite in the world folder
 - relaunch the map and enjoy!

init.lua

@@ -314,13 +314,14 @@ function realterrain.get_idx(haystack, needle)
 	return 0
 end
 
+-- SELECT the mechanism for loading the image which is later uesed by get_pixel()
 --@todo throw warning if image sizes do not match the dem size
 local width, height, dem, biomeimage, distimage
 
 if py then
 	py.execute("import Image")
 	py.execute("dem = Image.open('"..RASTERS..realterrain.settings.filedem.."')")
-	py.execute("biome = Image.open('"..RASTERS..realterrain.settings.filebiome.."')")
+	py.execute("biomeimage = Image.open('"..RASTERS..realterrain.settings.filebiome.."')")
 	local pybits = py.eval("dem.mode")
 	py.execute("w, l = dem.size")
 	width = tonumber(tostring(py.eval("w")))
@@ -652,12 +653,24 @@ minetest.register_on_generated(function(minp, maxp, seed)
 	local chugent = math.ceil((os.clock() - t0) * 1000)
 	print ("[DEM] "..chugent.." ms  mapchunk ("..cx0..", "..math.floor((y0 + 32) / 80)..", "..cz0..")")
 end)
+--the raw get pixel method that uses the selected method and accounts for bit depth
+function realterrain.get_raw_pixel(x,z, image)
+	local v
+	if py then --images for py need to be greyscale
+		v = py.eval(image..".getpixel(("..x..","..z.."))") --no bit depth conversion required
+		v = tonumber(tostring(v))
+		--print(e)
+	elseif magick then
+		v = math.floor(dem:get_pixel(col, row) * (2^tonumber(realterrain.settings.dembits))) --@todo change when magick autodetects bit depth
+	elseif imlib2 then
+		v = dem:get_pixel(col, row).red
+	end
+	return v
+end
 
---for now we are going to assume 32 bit signed elevation pixels
---and a header offset of
-
+--the main get pixel method that applies the scale and offsets
 function realterrain.get_pixel(x,z, elev_only)
-	local e, b = 0,0
+	local e, b
     local row,col = 0 - z + tonumber(realterrain.settings.zoffset), 0 + x - tonumber(realterrain.settings.xoffset)
 	--adjust for x and z scales
     row = math.floor(row / tonumber(realterrain.settings.zscale))
@@ -666,36 +679,15 @@ function realterrain.get_pixel(x,z, elev_only)
     --off the dem return false
     if ((col < 0) or (col > width) or (row < 0) or (row > length)) then return false end
     
-	if py then
-		e = py.eval("dem.getpixel(("..col..","..row.."))") --no bit depth conversion required
-		e = tonumber(tostring(e))
-		--print(e)
-	elseif magick then
-		e = math.floor(dem:get_pixel(col, row) * (2^tonumber(realterrain.settings.dembits))) --@todo change when magick autodetects bit depth
-	elseif imlib2 then
-		e = dem:get_pixel(col, row).red
-	end
+	e = realterrain.get_raw_pixel(col,row, "dem") or 0
 	--print("raw e: "..e)
 	--adjust for offset and scale
     e = math.floor((e / tonumber(realterrain.settings.yscale)) + tonumber(realterrain.settings.yoffset))
 	
     if elev_only then
 		return e
-	
-
 	else
-		if py then
-			b = py.eval("biome.getpixel(("..col..","..row.."))") --no bit depth conversion required
-			b = tonumber(tostring(b))
-		elseif biomeimage then
-			if magick then
-				b = biomeimage:get_pixel(col, row)
-				--print("raw biome: "..b)
-				b = math.floor(b * (2^tonumber(realterrain.settings.biomebits) ))
-			elseif imlib2 then
-				b = biomeimage:get_pixel(col, row).red
-			end
-		end
+		b = realterrain.get_raw_pixel(col,row, "biomeimage") or 0
 	end
     
     
@@ -777,6 +769,7 @@ function realterrain.get_curvature(n)
 	return curve
 end
 
+-- this is not tested with offsets and scales but should work
 function realterrain.get_distance(x,y,z)
 	local limit = realterrain.settings.dist_lim
     --off the dem return false
@@ -793,12 +786,7 @@ function realterrain.get_distance(x,y,z)
 			row = math.floor(row / tonumber(realterrain.settings.zscale))
 			col = math.floor(col / tonumber(realterrain.settings.xscale))
 			
-			if magick then
-				--any non-zero
-				value = math.ceil(distimage:get_pixel(col, row) --[[* (2^8 )]])
-			elseif imlib2 then
-				value = distimage:get_pixel(col, row).red
-			end
+			value = realterrain.get_raw_pixel(col,row, "dem")
 			if value > 0 then
 				table.insert(results, {x=i-x, z=j-z})
 			end