add isogen.draw_map(pos1, pos2) (#3)

* add `isogen.draw_map(pos1, pos2)`

* draw_map test

---------

Co-authored-by: BuckarooBanzay <BuckarooBanzay@users.noreply.github.com>

chatcommand.lua

@@ -18,6 +18,29 @@ worldedit.register_command("isogen", {
         local path = minetest.get_worldpath() .. "/" .. filename .. ".png"
         minetest.safe_file_write(path, png)
 
+        return true, "png saved: " .. #png .. " bytes"
+	end
+})
+
+worldedit.register_command("isogen_map", {
+	params = "[filename]",
+	description = "Generate a map image of the world region",
+	privs = {worldedit=true},
+	require_pos = 2,
+    parse = function(param)
+        return true, param
+    end,
+	func = function(name, filename)
+		local pos1, pos2 = worldedit.pos1[name], worldedit.pos2[name]
+        if not filename or filename == "" then
+            return false, "please specify a filename"
+        end
+
+        minetest.load_area(pos1, pos2)
+        local png = isogen.draw_map(pos1, pos2)
+        local path = minetest.get_worldpath() .. "/" .. filename .. ".png"
+        minetest.safe_file_write(path, png)
+
         return true, "png saved: " .. #png .. " bytes"
 	end
 })

common.lua

@@ -59,6 +59,11 @@ function isogen.probe_position(min, max, pos, ipos, list)
                 order = order,
                 node = node
             })
+
+            if not color.a or color.a == 255 then
+                -- solid color
+                break
+            end
         end
         pos = vector.add(pos, ipos)
     end

draw_map.lua

@@ -0,0 +1,45 @@
+
+function isogen.draw_map(pos1, pos2)
+    pos1, pos2 = vector.sort(pos1, pos2)
+
+    minetest.load_area(pos1, pos2)
+
+    local height = pos2.z - pos1.z + 1
+    local width = pos2.x - pos1.x + 1
+
+    local canvas = isogen.create_canvas(width, height)
+
+    -- left-right
+    for x=pos1.x,pos2.x do
+        -- top-down
+        for z=pos1.z,pos2.z do
+            local list = {}
+
+            -- up-down
+            for y=pos2.y,pos1.y,-1 do
+                local pos = vector.new(x, y, z)
+                local node = minetest.get_node(pos)
+                local color = isogen.get_color(node)
+                if color then
+                    table.insert(list, color)
+                    if not color.a or color.a == 255 then
+                        break
+                    end
+                end
+            end
+
+            -- draw from bottom-up (transparency)
+            if #list > 0 then
+                local pos = vector.new(x, 0, z)
+                for i=#list,1,-1 do
+                    local rel_pos = vector.subtract(pos, pos1)
+                    local cx = width - rel_pos.x - 1 -- inverted x axis
+                    local cy = rel_pos.z
+                    canvas:add_pixel(cx, cy, list[i])
+                end
+            end
+        end
+    end
+
+    return canvas:png()
+end

draw_map.spec.lua

@@ -0,0 +1,27 @@
+local pos1 = vector.new(200,100,100)
+local pos2 = vector.add(pos1, 15)
+
+mtt.emerge_area(pos1, pos2)
+
+mtt.register("draw_map", function(callback)
+    minetest.load_area(pos1, pos2)
+
+    minetest.set_node(pos1, { name = "mapgen_stone" })
+    minetest.set_node(vector.add(pos1, vector.new(1, 0, 0)), { name = "mapgen_stone" })
+    minetest.set_node(vector.add(pos1, vector.new(2, 0, 0)), { name = "mapgen_stone" })
+    minetest.set_node(vector.add(pos1, vector.new(0, 0, 1)), { name = "mapgen_water_source" })
+    minetest.set_node(vector.add(pos1, vector.new(1, 0, 1)), { name = "mapgen_water_source" })
+
+    -- sanity tests
+    local node = minetest.get_node(pos1)
+    assert(node.name ~= "air")
+    assert(node.name ~= "ignore")
+
+    local png = isogen.draw_map(pos1, pos2)
+    local path = minetest.get_worldpath() .. "/test_map.png"
+    minetest.safe_file_write(path, png)
+
+    print("png saved: " .. #png .. " bytes")
+
+    callback()
+end)

init.lua

@@ -5,6 +5,7 @@ dofile(MP.."/common.lua")
 dofile(MP.."/colors.lua")
 dofile(MP.."/canvas.lua")
 dofile(MP.."/draw_cube.lua")
+dofile(MP.."/draw_map.lua")
 dofile(MP.."/draw.lua")
 
 if minetest.get_modpath("worldedit_commands") then
@@ -15,5 +16,6 @@ if minetest.get_modpath("mtt") and mtt.enabled then
     dofile(MP.."/common.spec.lua")
     dofile(MP.."/colors.spec.lua")
     dofile(MP.."/draw_cube.spec.lua")
+    dofile(MP.."/draw_map.spec.lua")
     dofile(MP.."/draw.spec.lua")
 end

readme.md

@@ -40,6 +40,21 @@ local path = minetest.get_worldpath() .. "/iso.png"
 minetest.safe_file_write(path, png)
 ```
 
+## `isogen.draw_map(pos1, pos2)`
+
+Renders a map image and returns the png data
+
+Example:
+```lua
+local pos1 = vector.new(0,0,0)
+local pos2 = vector.new(16,16,16) -- NOTE: larger regions require more memory
+
+-- render and save to world-directory
+local png = isogen.draw_map(pos1, pos2)
+local path = minetest.get_worldpath() .. "/map.png"
+minetest.safe_file_write(path, png)
+```
+
 ## `isogen.create_canvas(width, height)`
 
 Creates a canvas to set and get pixels