Large refactor to avoid the need to use map() and camera() - the new approach just re-calculates the local world and allows us to scroll 'smoothly' forever.

a_pleasant_stroll.p8

@@ -2,9 +2,8 @@ pico-8 cartridge // http://www.pico-8.com
 version 18
 __lua__
 #include debug.lua
-#include data.lua
 #include sound.lua
-#include mapgen.lua
+#include world.lua
 #include player.lua
 #include main.lua
 __gfx__

data.lua

@@ -1,84 +0,0 @@
--- data shared between modules goes here, both constants and mutable data.
--- also contains some functions that act solely on the data
---
--- also has commented "fake constants" that are replaced by actual values, for
--- reference.
---
--- also see index_map.md for more "constant" values
-
-function init_data()
-   -- block_size = 64
-   -- biome_size = 128
-
-   -- the indices here are sprite numbers.
-   object_interaction_map = {
-      -- bush
-      [3] = {
-         replacement = 17,
-         sfx = 13,
-         drop = 68
-      },
-
-      -- tree
-      [4] = {
-         replacement = 14,
-         sfx = 11,
-         drop = 64
-      },
-
-      -- big mushroom
-      [8] = {
-         replacement = 16,
-         sfx = 12,
-         drop = 65
-      },
-
-      -- cactus w/ flower
-      [10] = {
-         replacement = 15,
-         sfx = 12,
-         drop = 67
-      },
-
-      -- cactus
-      [13] = {
-         replacement = 15,
-         sfx = 12,
-         drop = 66
-      }
-   }
-
-   -- initialize a ring buffer of changed positions. In use, this will be keyed
-   -- using strings of the form mod_buffer["x:y"], using absolute world
-   -- coordinates. this is to flatten the buffer so that #mod_cache is useful
-   -- for checking against max_mod_entries.
-   max_mod_entries = 4096
-   mod_buffer = {}
-end
-
--- x and y are global coords
-function get_mod_key(x, y)
-   return tostr(x) .. ":" .. tostr(y)
-end
-
--- x and y are map-local coords
-function write_map_change(new_sprite, x, y)
-   local global_x, global_y = calculate_world_pos(x, y)
-   if #mod_buffer >= max_mod_entries then
-      cull_mod_buffer()
-   end
-
-   mod_buffer[get_mod_key(global_x, global_y)] = new_sprite
-end
-
-function cull_mod_buffer()
-   -- we cull 10% of the mod buffer at a time
-   -- todo: implement this
-end
-
-function calculate_world_pos(x, y)
-   -- player_pos_[xy] is world absolute, so we can get the world pos of map 0,0,
-   -- then add x and y back in.
-   return player_pos_x - camera_pos_x - 8 + x,
-          player_pos_y - camera_pos_y - 8 + y
-end

main.lua

@@ -1,24 +1,23 @@
 function _init()
-   init_data()
+   init_sound""
-   init_sound()
+   init_world""
-   init_mapgen()
    init_player(32, 32)
-   generate_map(0, 0)
+   init_debug""
-   init_debug()
 end
 
 
 function _update()
-   handle_input()
+   handle_input""
-   handle_map_update()
+--   handle_map_update""
 end
 
 function _draw()
-   cls()
+   cls""
    -- the screen is 128x128 pixels, so it fits 16x16 sprites
-   map(camera_pos_x, camera_pos_y, 0, 0, 16, 16)
+   --   map(camera_pos_x, camera_pos_y, 0, 0, 16, 16)
-   draw_player()
+   draw_world_segment(player_pos_x, player_pos_y)
-   debug_print()
+   draw_player""
+   debug_print""
 end
 
 -- decide whether we need to regenerate the map.

world.lua

@@ -1,8 +1,6 @@
 --- Procedural generation methods
 
-function init_mapgen()
+function init_world()
-   uid_seed = 2229 -- arbitrarily chosen number
-
    -- Metadata for different biomes
    -- tile_frequencies tuples are {frequency, sprite_index}, see index_map.md
    -- frequencies by convention add up to 1000, but this is arbitrary, the
@@ -45,6 +43,62 @@ function init_mapgen()
 
       build_biome(biome, biome_data[biome])
    end
+
+   -- the indices here are sprite numbers.
+   object_interaction_map = {
+      -- bush
+      [3] = {
+         replacement = 17,
+         sfx = 13,
+         drop = 68
+      },
+
+      -- tree
+      [4] = {
+         replacement = 14,
+         sfx = 11,
+         drop = 64
+      },
+
+      -- big mushroom
+      [8] = {
+         replacement = 16,
+         sfx = 12,
+         drop = 65
+      },
+
+      -- cactus w/ flower
+      [10] = {
+         replacement = 15,
+         sfx = 12,
+         drop = 67
+      },
+
+      -- cactus
+      [13] = {
+         replacement = 15,
+         sfx = 12,
+         drop = 66
+      }
+   }
+
+   -- initialize a ring buffer of changed positions. In use, this will be keyed
+   -- using strings of the form mod_buffer["x:y"], using absolute world
+   -- coordinates. this is to flatten the buffer so that #mod_cache is useful
+   -- for checking against max_mod_entries.
+   max_mod_entries = 4096
+   mod_buffer = {}
+end
+
+-- draw the sprites for this part of the world to the screen
+-- this calculates everything about the world fresh every frame,
+-- but pico-8 handles this just fine!
+function draw_world_segment(start_x, start_y)
+   for x=0,15 do
+      for y=0,15 do
+         spr(get_tile(start_x-8+x, start_y-8+y), x*8, y*8)
+      end
+   end   
 end
 
 -- build the lookup table for a given biome, based on the biome_meta data for
@@ -100,15 +154,34 @@ function get_tile(pos_x, pos_y)
    return biome.tile_lookup[(uid % #biome.tile_lookup) + 1]
 end
 
--- generate the map and writes to the map area from 0 - block_size,
+
--- assuming 'start' as the top-left corner of the map area to generate.
+---
--- writes block_size x block_size tiles
+--- mod buffer functions - these handle parts of the world map that have
--- after a call to generate_map you should always center the camera/player over the map, i.e.
+--- changed from their 'default' position
--- camera at { (block_size / 2) - 8, (block_size / 2) - 8 }
+---
-function generate_map(start_x, start_y)
+--- todo: the mod buffer eventually needs to be a bit more elaborate.
-   for x=0,63 do
+---   we need to make it possible to cull only old and unimportant changes,
-      for y=0,63 do
+---   so each entry needs a 'critical' flag and something to indicate order
-         mset(x, y, get_tile(start_x+x, start_y+y))
+---   added. We could keep 2 buffers for the latter, one that's just keys
-      end
+---   in an array... expensive though.
-   end
+---
+
+-- x and y are global coords
+function get_mod_key(x, y)
+   return tostr(x) .. ":" .. tostr(y)
+end
+
+-- x and y are map-local coords
+function write_map_change(new_sprite, x, y)
+   local global_x, global_y = calculate_world_pos(x, y)
+   if #mod_buffer >= max_mod_entries then
+      cull_mod_buffer()
+   end
+
+   mod_buffer[get_mod_key(global_x, global_y)] = new_sprite
+end
+
+function cull_mod_buffer()
+   -- we cull 10% of the mod buffer at a time
+   -- todo: implement this
 end