MAKE A ONE-BUTTON GAME USING PICO8 #4 – OBSTACLES
In this port, we will add obstacles into the block and the game will reset the player’s character position into starting position when the player’s character touch obstacles.
ADD VARIABLE AND FUNCTION FOR SUPPORT OBSTACLES IN THE BLOCK
First, we need to modify the function for creating a block by adding a variable for keeping obstacles data.
function create_block(x,y,w,h)
return {x=x,y=y,w=w,h=h,obstacles={}}
end
Second, we add a new function to create obstacle data into the block data. currently, It only data for obstacle’s position inside the block. The value between 0 to 1. 0 = left, 1 = right
function add_obstacle(b,v) if (b == nil) return add(b.obstacles, {value=v}) end
And the last one, we need to modify the function for drawing block to support obstacle.
function draw_block(b,c)
if (b == nil) return
rect(b.x,b.y,b.x+b.w,b.y-b.h,c)
for obs in all(b.obstacles) do
print("✽", b.x + (b.w*obs.value), b.y - 6, 8)
end
end
ADD FUNCTIONS FOR THE PLAYER'S CHARACTER
We need to make the player’s character interact with obstacles. We will add 2 new functions for collision detect and reset the player’s character to start position.
function player_hit_obstacle(b)
if b == nil then return false end for o in all(b.obstacles) do local dx = player.x - (b.x + b.w * o.value) local dy = player.y - b.y local distance = sqrt(dx*dx+dy*dy) if distance < 3 then return true end end end
function player_reset() player = {x=64,y=64,di=1,jump_counter=0,ground=true} current_block = block_list[1] end
PUT EVERYTHING TOGETHER
We will add obstacles into a second and third block and make _update60() call function to detect collision between the player’s character and obstacles in the current block.
function _init() add(block_list, create_block(16,64,96,8)) add(block_list, create_block(16,56,96,8)) add(block_list, create_block(16,48,96,8)) current_block = block_list[1] add_obstacle(block_list[2], 0.8) add_obstacle(block_list[3], 0.2) add_obstacle(block_list[3], 0.5) end function _update60() player_running() player_jumping() player_apply_gravity() player_find_new_current_block() local hit_result = player_hit_obstacle(current_block) if hit_result == true then player_reset() end end
RESULT
SOURCE CODE
player = {x=64,y=64,di=1,jump_counter=0,ground=true} current_block = nil block_list = {} function create_block(x,y,w,h) return {x=x,y=y,w=w,h=h,obstacles={}} end function draw_block(b,c) if (b == nil) return rect(b.x,b.y,b.x+b.w,b.y-b.h,c) for obs in all(b.obstacles) do print("✽", b.x + (b.w*obs.value), b.y - 6, 8) end end function add_obstacle(b,v) if (b == nil) return add(b.obstacles, {value=v}) end function is_inside_block(x,y,b) if (b == nil) return if x >= b.x and x < b.x + b.w then if y <= b.y and y > b.y - b.h then return true end end return false end function player_running() local next_px = player.x + player.di if is_inside_block(player.x, player.y, current_block) == true and is_inside_block(next_px, player.y, current_block) == false then player.di = player.di * -1 next_px = player.x + player.di end player.x = next_px end function player_jumping() if btnp(4) then if player.jump_counter == 0 and player.ground == true then player.jump_counter = 20 player.ground = false end end local next_py = player.y if player.jump_counter > 0 then player.jump_counter -= 1 if player.jump_counter > 10 then next_py = player.y - 1 else next_py = player.y end end player.y = next_py end function player_apply_gravity() local next_py = player.y if player.ground == false then if player.jump_counter <= 0 then next_py += 1 if is_inside_block(player.x, player.y, current_block) == true and is_inside_block(player.x, next_py, current_block) == false then next_py = player.y player.ground = true end end end player.y = next_py end function player_find_new_current_block() if player.ground == false and is_inside_block(player.x, player.y, current_block) == false then for b in all(block_list) do if is_inside_block(player.x, player.y, b) == true then current_block = b break end end end end function player_hit_obstacle(b) if b == nil then return false end for o in all(b.obstacles) do local dx = player.x - (b.x + b.w * o.value) local dy = player.y - b.y local distance = sqrt(dx*dx+dy*dy) if distance < 3 then return true end end end function player_reset() player = {x=64,y=64,di=1,jump_counter=0,ground=true} current_block = block_list[1] end function _init() add(block_list, create_block(16,64,96,8)) add(block_list, create_block(16,56,96,8)) add(block_list, create_block(16,48,96,8)) current_block = block_list[1] add_obstacle(block_list[2], 0.8) add_obstacle(block_list[3], 0.2) add_obstacle(block_list[3], 0.5) end function _update60() player_running() player_jumping() player_apply_gravity() player_find_new_current_block() local hit_result = player_hit_obstacle(current_block) if hit_result == true then player_reset() end end function _draw() cls(0) print("웃", player.x-3, player.y - 5, 7) for b in all(block_list) do draw_block(b, 7) end end function _draw() cls(0) print("웃", player.x-3, player.y - 5, 7) for b in all(block_list) do draw_block(b, 7) end end