CS2D 
How to do image collision detection?
1 
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Apparently, I think Gradius is cool and I want to implement the Option thingy into CS2D. You know the glowing orb that follow player and shoot right?
So far I can make the image follow me smoothly. I can also make them shot snowball too.
But I think snowball and rocket are boring so I make a custom bullet.
But the problem is I don't know how to do collision detection for that bullet. If anyone know how, please let me know.
Updated: The collision detection is working now. However, there a bug I still don't know why. When the bullet collide somewhere near the drone, all the next bullets range get shorten. I can't shot any further until I stop holding right mouse button for a while.
I guess it have something to do with the freeimage timer on line 97.
But without it, the bullet won't disappear.
Here is the code that I use to make bullet. Sorry for posting a long code. If you want to see where the problem is, just skip to line 80 - 146:
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bullet_speedDam = 1 --bullet speed dam -- more mean slower
--create bullet
drone_id = {}
drone_x = {}
drone_y = {}
--player last positions
drone_player_lastx = {}
drone_player_lasty = {}
drone_player_index_use = 1 --at which pos drone is tracing
drone_player_index_write = 1 --at which index player last pos got update
drone_update = false --check when player last pos should be updated
drone_moving = false --check when drone should start chasing player
drone_chain_length = 5 --drone chain's length
drone_chain_distance = 0 --extra distance between each drone
bullet_speedDam = 3--bullet speed dam -- more mean slower
bullet_id = {}
bullet_id_max = 3200
bullet_id_index = 1
bullet_id_lifespand = {}
--key check variables and key bind
key_hold_w = false
key_hold_a = false
key_hold_s = false
key_hold_d = false
key_hold_mouse1 = false
addbind("W")
addbind("A")
addbind("S")
addbind("D")
addbind("mouse1")
--create drone
function make_drone(d_id)
drone_id[d_id] = image("gfx/sprites/flare1.bmp",player(1,"x"),player(1,"y"),0)
imagecolor(drone_id[d_id],255,100,0)
imageblend(drone_id[d_id],1)
tween_animate(drone_id[d_id],100,4)
end
function drone_follow()
if(key_hold_w or key_hold_a or key_hold_s or key_hold_d) then
drone_player_lastx[drone_player_index_write] = player(1,"x")
drone_player_lasty[drone_player_index_write] = player(1,"y")
drone_player_index_write = drone_player_index_write + 1
if(drone_player_index_write > drone_chain_length) then
drone_player_index_write = 1
drone_moving = true
end
if(drone_moving) then
drone_player_index_use = drone_player_index_use + 1
if(drone_player_index_use > drone_chain_length) then
drone_player_index_use = 1
end
for i = 0, 1 do
if(drone_player_index_use - i - drone_chain_distance>= 1) then
drone_x[i+1] = drone_player_lastx[drone_player_index_use - i - drone_chain_distance]
drone_y[i+1] = drone_player_lasty[drone_player_index_use - i - drone_chain_distance]
tween_move(drone_id[i+1],100,drone_x[i+1],drone_y[i+1])
else
drone_x[i+1] = drone_player_lastx[drone_chain_length + (drone_player_index_use - i - drone_chain_distance)]
drone_y[i+1] = drone_player_lasty[drone_chain_length + (drone_player_index_use - i - drone_chain_distance)]
tween_move(drone_id[i+1],100,drone_x[i+1],drone_y[i+1])
end
end
end
end
end
--create bullet
function spawn_bullet(id,x,y,dir,dis)
local lifespand
local i_id
if(x ~= nil and y ~= nil) then
i_id = image("gfx/sprites/raindrop.bmp",x,y,0)
dir = (dir - 90) --direction
imagecolor(i_id,100,100,255)
imageblend(i_id,1)
imagepos(i_id,x,y,dir - 90)
--make bullet move toward the destination
tween_move(i_id,bullet_speedDam * dis, x + dis * math.cos(math.rad(dir)), y + dis * math.sin(math.rad(dir)), dir - 90)
--free bullet when it's reach max distance
timer(bullet_speedDam * dis,"freeimage",i_id)
--collition detection call -- when to call this using timer?
image_collision(i_id,lifespand)
end
end
function image_collision(i_id,lifespand) --how should I do this?
local x
local y
local hitbox
local hitList
local hitWall = false
local tile_property
--msg(type(lifespand))
if(imageparam(i_id,"x") and imageparam(i_id,"y")) then
x = imageparam(i_id,"x") + 16 * math.cos(math.rad(imageparam(i_id,"rot") + 90))
y = imageparam(i_id,"y") + 16 * math.sin(math.rad(imageparam(i_id,"rot") + 90))
--local hitbox = image("gfx/sprites/flare1.bmp",x,y,0)
--imagecolor(hitbox,255,0,0)
--imageblend(hitbox,1)
--tween_animate(hitbox,100,4)
hitList = closeplayers(x,y,16,1)
tile_property = tile((x - 16)/ 32,(y - 16) / 32,"property")
if(tile_property == 1 or tile_property == 3 or tile_property == 5) then
hitWall = true
end
if(hitWall) then
msg("hit wall")
freeimage(i_id)
-- freeimage(hitbox)
else
if (hitList[1] ~= nil) then
msg("hit player id: "..hitList[1].." at index"..1)
freeimage(i_id)
-- freeimage(hitbox)
else
--set up next function call
-- timer(10,"freeimage",hitbox)
--life = life - 10
timer(10,"image_collision",i_id,life)
end
end
end
end
--make drone on spawn
addhook("spawn","hook_spawn")
function hook_spawn(id)
--make drone for player 1
if (id == 1) then
make_drone(1)
make_drone(2)
--make_drone(3)
--make_drone(4)
end
end
--key check
addhook("key","hook_key")
function hook_key(id,key,state)
if(id == 1) then
if(key == 'W') then
if(state == 1) then
key_hold_w = true
elseif(state == 0) then
key_hold_w = false
end
elseif(key == 'A') then
if(state == 1) then
key_hold_a = true
elseif(state == 0) then
key_hold_a = false
end
elseif(key == 'S') then
if(state == 1) then
key_hold_s = true
elseif(state == 0) then
key_hold_s = false
end
elseif(key == 'D') then
if(state == 1) then
key_hold_d = true
elseif(state == 0) then
key_hold_d = false
end
elseif(key == "mouse1") then
if(state == 1) then
key_hold_mouse1 = true
elseif(state == 0) then
key_hold_mouse1 = false
end
end
end
end
addhook("ms100","hook_ms100")
function hook_ms100()
--make drone follow player 1
drone_follow()
--rapid fire mode
if(key_hold_mouse1) then
for i = 1, 4 do
--parse("spawnprojectile "..id.." 75 "..drone_x[i].." "..drone_y[i].." 360 "..player(1,"rot")) --shot snowball
spawn_bullet(1,drone_x[i],drone_y[i],player(1,"rot"),360)
end
end
end
addhook("attack","hook_attack")
function hook_attack(id)
--attack fire mode
if(id == 1) then
for i = 1, 2 do
--parse("spawnprojectile "..id.." 75 "..drone_x[i].." "..drone_y[i].." 360 "..player(1,"rot"))
--spawn_bullet(1,drone_x[i],drone_y[i],player(1,"rot"),360)
end
end
end
addhook("die","hook_die")
function hook_die(id)
--free drone when die
if(id == 1) then
for i = 1, 2 do
freeimage(drone_id[i])
end
end
end
edited 2×, last 22.10.19 08:15:08 am
