Tuto tiny-ecs 2d platformer Part 10 Collision System
From GiderosMobile
The Collision System
This System is where all the fun happens: collisions. Here we deal with cBump for the collisions, cBump is the physics engine we use. We also implement gravity, coyote timer, input buffering, ...
The list of collisions:
-- physics flags
ent.isstepcontacts = false
ent.isfloorcontacts = false
ent.isladdercontacts = false
ent.isptpfcontacts = false -- pass through platform
ent.ismvpfcontacts = false -- moving platform
ent.iswallcontacts = false
ent.isspringcontacts = false
Let's go!
sCollision.lua
The cBump physics engine is a Gideros plugin. I cannot explain in details how it works but I will do my best!
- when we create an Entity, we add it to tiny-ecs world, Gideros stage and also cBump world. This is done when we parse the Tiled.lua file. For example, here we add a moving platform:
--EMvpf:init(xid, xspritelayer, xpos, xtexpath, xcolor, w, h, dx, dy, xdir, xspeed, xbgfxlayer)
local e = EMvpf.new(
xid, xlayers["actors"], vpos, xtexpath, xcolor, o.width, o.height,
dx, dy, xdir, vspeed, nil, xlayers["bgfx"]
)
xtiny.tworld:addEntity(e)
xbworld:add(e, e.pos.x, e.pos.y, e.collbox.w, e.collbox.h) -- cBump world
e.sprite:setPosition(e.pos + vector(e.collbox.w/2, -e.h/2+e.collbox.h))
- once an Entity exists in cBump world we can code how it collides in the physics world
- the player1 Entity is moved by the player using the keyboard. An enemy Entity is moved using the AI System (isup, isdown, isleft, isright). Some other entities are moved using their own systems
- cBump uses a collisionfilter to process collisions between entities in the physics world
- then cBump resolves the Entity collision ("touch", "cross", "slide" or "bounce") using the move function:
local goalx = ent.pos.x + ent.body.vx * dt
local goaly = ent.pos.y + ent.body.vy * dt
local nextx, nexty, collisions, len = self.bworld:move(ent, goalx, goaly, collisionfilter)
We will explain some more after we create the file.
Please create a file "sCollision.lua" in the "_S" folder and the code:
SCollision = Core.class()
function SCollision:init(xtiny, xbworld, xplayer1) -- tiny function
xtiny.processingSystem(self) -- called once on init and every update
self.tiny = xtiny
self.bworld = xbworld
self.player1 = xplayer1
end
function SCollision:filter(ent) -- tiny function
return ent.collbox and ent.body and
not (ent.isprojectile or ent.ismvpf or ent.isdoor)
end
function SCollision:onAdd(ent) -- tiny function
end
function SCollision:onRemove(ent) -- tiny function
end
local p1rangetoofarx = myappwidth*2 -- disable systems to save some CPU, magik XXX
local p1rangetoofary = myappheight*2 -- disable systems to save some CPU, magik XXX
function SCollision:process(ent, dt) -- tiny function
-- OUTSIDE VISIBLE RANGE
if ent.isnme then
if (ent.pos.x > self.player1.pos.x + p1rangetoofarx or
ent.pos.x < self.player1.pos.x - p1rangetoofarx) or
(ent.pos.y > self.player1.pos.y + p1rangetoofary or
ent.pos.y < self.player1.pos.y - p1rangetoofary) then
ent.doanimate = false
return
end
end
-- physics flags
ent.isstepcontacts = false
ent.isfloorcontacts = false
ent.isladdercontacts = false
ent.isptpfcontacts = false
ent.ismvpfcontacts = false
ent.iswallcontacts = false
ent.isspringcontacts = false
-- _____ ____ _ _ _____ _____ _____ ____ _ _
-- / ____/ __ \| | | | |_ _|/ ____|_ _/ __ \| \ | |
--| | | | | | | | | | | | (___ | || | | | \| |
--| | | | | | | | | | | \___ \ | || | | | . ` |
--| |___| |__| | |____| |____ _| |_ ____) |_| || |__| | |\ |
-- \_____\____/|______|______|_____|_____/|_____\____/|_| \_|
-- ______ _____ _ _______ ______ _____
--| ____|_ _| | |__ __| ____| __ \
--| |__ | | | | | | | |__ | |__) |
--| __| | | | | | | | __| | _ /
--| | _| |_| |____| | | |____| | \ \
--|_| |_____|______|_| |______|_| \_\
local function collisionfilter(item, other) -- "touch", "cross", "slide", "bounce"
if other.isnpc then return "cross"
elseif other.isdoor then return "slide" -- needed 20250720
elseif other.iswall then return "slide" -- "touch"
elseif other.isfloor then return "slide"
elseif other.isptpf then
if item.isdown and item.isup then -- prevents ptpf while holding both up and down keys
item.wasdown = true
item.wasup = true
end
if item.isdown and not item.wasdown then
return "cross"
end
if item.body.vy > 0 then -- actor going down
local itembottom = item.pos.y + item.collbox.h
local otherbottom = other.pos.y -- don't add margin here!
if itembottom <= otherbottom then return "slide" end
end
if item.iswalkingnme and item.breed == "C" then
return "slide"
end
elseif other.ismvpf then
if item.isdown and item.isup then -- prevents pt mvpf while holding both up and down keys
item.wasdown = true
item.wasup = true
end
if item.isdown and not item.wasdown then
if other.isptmvpf then return "cross" end -- passthrough moving pf
end
if item.body.vy > 0 then -- actor going down
local itembottom = item.pos.y + item.collbox.h
local otherbottom = other.pos.y + 1
if other.body.vy < 0 then -- mvpf going up
otherbottom += 1 -- margin prevents player from falling when the pf is going up
end
if itembottom <= otherbottom then return "slide" end
end
elseif other.isspring then return "slide"
elseif other.isspike then return "slide"
else return "cross"
end
end
-- _____ ____ _ _ __ __ _____
-- / ____| _ \| | | | \/ | __ \
--| | | |_) | | | | \ / | |__) |
--| | | _ <| | | | |\/| | ___/
--| |____| |_) | |__| | | | | |
-- \_____|____/ \____/|_| |_|_|
local goalx = ent.pos.x + ent.body.vx * dt
local goaly = ent.pos.y + ent.body.vy * dt
local nextx, nexty, collisions, len = self.bworld:move(ent, goalx, goaly, collisionfilter)
-- _____ ____ _ _ _____ _____ _____ ____ _ _ _____
-- / ____/ __ \| | | | |_ _|/ ____|_ _/ __ \| \ | |/ ____|
--| | | | | | | | | | | | (___ | || | | | \| | (___
--| | | | | | | | | | | \___ \ | || | | | . ` |\___ \
--| |___| |__| | |____| |____ _| |_ ____) |_| || |__| | |\ |____) |
-- \_____\____/|______|______|_____|_____/|_____\____/|_| \_|_____/
-- COLLISION FROM ANY SIDES
for i = 1, len do
local item = collisions[i].item
local other = collisions[i].other
local normal = collisions[i].normal
--
if other.isvoid then
if item.isplayer1 then
item.restart = true -- load lose scene?
else
item.currlives = 0
item.readytoremove = true
end
elseif item.isplayer1 and other.isexit then
g_currlevel += 1
item.restart = true
elseif other.isladder then
item.body.currcoyotetimer = item.body.coyotetimer
item.isladdercontacts = true
if item.currlives <= 0 then
item.readytoremove = true -- only remove actor when 'grounded'
end
elseif other.isptpf then
item.isptpfcontacts = true
elseif other.isstep then -- CBump stairs effect ;-)
item.isstepcontacts = true
elseif other.ismvpf then
if item.body.vy > 0 then -- actor going down
local itembottom = item.pos.y + item.collbox.h
local otherbottom = other.pos.y + 1 -- some margin prevent player from sliding/falling
if itembottom <= otherbottom then -- actor above mvpf
item.ismvpfcontacts = true
item.body.currjumpcount = item.body.jumpcount
item.body.currcoyotetimer = item.body.coyotetimer
-- item.body.vy = 0 -- don't reset velocity y here because prevents ptpf!
end
if item.currlives <= 0 then
item.readytoremove = true -- only remove actor when 'grounded'
end
end
if item.isleft and not item.isright and other.body.vx < 0 then
item.body.vx = -item.body.currspeed*0.9 -- slow down speed on mvpf, you choose!
elseif item.isright and not item.isleft and other.body.vx < 0 then
item.body.vx = item.body.currspeed*0.9 -- slow down speed on mvpf, you choose!
elseif (item.isleft and item.isright) and other.body.vx < 0 then
item.body.vx = other.body.vx
elseif not(item.isleft and item.isright) and other.body.vx < 0 then
item.body.vx = other.body.vx
elseif item.isleft and not item.isright and other.body.vx > 0 then
item.body.vx = -item.body.currspeed*0.9 -- slow down speed on mvpf, you choose!
elseif item.isright and not item.isleft and other.body.vx > 0 then
item.body.vx = item.body.currspeed*0.9 -- slow down speed on mvpf, you choose!
elseif (item.isleft and item.isright) and other.body.vx > 0 then
item.body.vx = other.body.vx
elseif not (item.isleft and item.isright) and other.body.vx > 0 then
item.body.vx = other.body.vx
elseif item.isleft and not item.isright and other.body.vx == 0 then
item.body.vx = -item.body.currspeed*0.9 -- slow down speed on mvpf, you choose!
elseif item.isright and not item.isleft and other.body.vx == 0 then
item.body.vx = item.body.currspeed*0.9 -- slow down speed on mvpf, you choose!
elseif (item.isleft and item.isright) and other.body.vx == 0 then
item.body.vx = 0
elseif not (item.isleft and item.isright) and other.body.vx == 0 then
item.body.vx = 0
end
elseif other.iswall then
item.body.currjumpcount = item.body.jumpcount
item.body.currcoyotetimer = item.body.coyotetimer + 1*8 -- increase timer for fun, magik XXX
item.iswallcontacts = true
item.wasonwall = true
-- item.wasup = false -- you can uncomment this line, GAMEPLAY: walls jumping too permissive
elseif other.isspring then
item.body.vy = -other.vy -- reset velocity y (don't accumulate gravity)
item.isspringcontacts = true
if item.currlives <= 0 then
item.readytoremove = true -- only remove actor when 'grounded'
end
elseif other.isspike then
item.body.vx = item.body.currspeed*5*-item.flip -- 3, magik XXX
item.body.vy = -item.body.currupspeed*0.7 -- magik XXX
if item.isplayer1 then
item.isdirty = true
item.damage = 1
end
if item.currlives <= 0 then
item.readytoremove = true -- only remove actor when 'grounded'
end
item.wasup = false
end
-- COLLISION FROM TOP
if normal.y == -1 then
if other.isfloor then
item.body.vy = 0 -- reset velocity y (don't accumulate gravity)
item.isfloorcontacts = true
item.body.currjumpcount = item.body.jumpcount
item.body.currcoyotetimer = item.body.coyotetimer
if item.currlives <= 0 then
item.readytoremove = true -- only remove actor when 'grounded'
end
elseif other.isptpf then
item.body.vy = 0 -- reset velocity y (don't accumulate gravity)
item.isptpfcontacts = true
item.body.currjumpcount = item.body.jumpcount
item.body.currcoyotetimer = item.body.coyotetimer
if item.currlives <= 0 then
item.readytoremove = true -- only remove actor when 'grounded'
end
elseif other.isnme and item.isplayer1 then -- player1 on top of nme
other.isdirty = true
other.damage = 1
item.body.currjumpcount = item.body.jumpcount
if item.isup then
item.body.vy = -ent.body.currupspeed*1.1
else
item.body.vy = -item.body.currupspeed*0.7 -- magik XXX, linked to 'stomp'
end
elseif other.isnme and item.isnme then -- nme on top of nme
item.body.currjumpcount = item.body.jumpcount
if item.isup then
item.body.vy = -ent.body.currupspeed*1.1
else
item.body.vy = -item.body.currupspeed*0.7 -- magik XXX, linked to 'stomp'
end
if item.currlives <= 0 then
item.readytoremove = true -- only remove actor when 'grounded'
end
elseif other.isplayer1 and item.isnme then -- nme on top of player1
other.isdirty = true
other.damage = 1
item.wasup = false -- ??? XXX
item.body.currjumpcount = item.body.jumpcount
item.body.currinputbuffer = item.body.inputbuffer
item.body.currcoyotetimer = item.body.coyotetimer
end
-- COLLISION FROM BOTTOM
elseif normal.y == 1 then
if other.isfloor then -- cancel body gravity when hitting from below (can adjust)
item.body.vy *= 0.5 -- = 0
end
end
-- COLLISION FROM SIDES, -1 collision from item right, 1 collision from item left
if normal.x == -1 or normal.x == 1 then
if item.isplayer1 and other.isfloor then
item.body.vx = -item.flip
elseif item.isnme and other.isdoor then
item.isleft, item.isright = not item.isleft, not item.isright
elseif item.isnme and other.isfloor then
if normal.x == -1 and not item.isleftofplayer then
item.isleft, item.isright = true, false
elseif normal.x == 1 and item.isleftofplayer then
item.isleft, item.isright = false, true
end
end
end
-- PLAYER1
if item.isplayer1 and other.iscollectible then
other.isdirty = true
if other.eid:find("key") then -- add key to inventory
self.tiny.player1inventory[other.eid:sub(4)] = true -- eid with "key" truncated
-- print("key", other.eid, dt)
end
end
end
-- _____ _____ __ _______ _________ __
-- / ____| __ \ /\ \ / /_ _|__ __\ \ / /
--| | __| |__) | / \ \ / / | | | | \ \_/ /
--| | |_ | _ / / /\ \ \/ / | | | | \ /
--| |__| | | \ \ / ____ \ / _| |_ | | | |
-- \_____|_| \_\/_/ \_\/ |_____| |_| |_|
-- gravity after collisions because ptpfs may modify actor body vy
if ent.body.vy < 0 then -- going up
ent.body.vy += 3*8 * ent.body.currmass -- gravity, magik XXX
else -- going down
ent.body.vy += 3*8 * ent.body.currmass -- 3*8, gravity, magik XXX
if ent.body.vy > 500 then -- 500, cap falling speed
ent.body.vy = 500
end
if ent.wasonmvpf then -- prevent fast fall when going off pf
ent.body.vy = ent.body.currupspeed*0.25 -- *0.5, ent going down mvpf, magik XXX
ent.wasonmvpf = false
elseif ent.wasonwall then -- ent wall sliding
ent.body.vy = ent.body.currupspeed*0.01 -- *0.25, magik XXX
ent.wasonwall = false
end
end
-- _____ _ ___ _______ _____ _____ _____
-- | __ \| | | \ \ / / ____|_ _/ ____|/ ____|
-- | |__) | |__| |\ \_/ / (___ | || | | (___
-- | ___/| __ | \ / \___ \ | || | \___ \
-- | | | | | | | | ____) |_| || |____ ____) |
-- |_| |_| |_| |_| |_____/|_____\_____|_____/
if ent.body.currinputbuffer > 0 then -- floor input buffer
ent.body.currinputbuffer -= 1
end
if ent.body.currcoyotetimer > 0 then -- coyote time
ent.body.currcoyotetimer -= 1
end
if ent.body.currdashtimer > 0 then -- dash
ent.body.currdashtimer -= 1
end
if ent.body.currdashcooldown > 0 then -- dash cooldown
ent.body.currdashcooldown -= 1
end
-- IS ON STEP
if ent.isstepcontacts then
-- if ent.isplayer1 then print("isstepcontacts", dt) end
if ent.isleft and not ent.isright then -- LEFT
ent.animation.curranim = g_ANIM_RUN_R
ent.flip = -1
ent.body.vx = -ent.body.currspeed
ent.body.vy = -ent.body.currupspeed*0.4 -- 0.5, step climb speed here XXX
elseif ent.isright and not ent.isleft then -- RIGHT
ent.animation.curranim = g_ANIM_RUN_R
ent.flip = 1
ent.body.vx = ent.body.currspeed
ent.body.vy = -ent.body.currupspeed*0.4 -- 0.5, step climb speed here XXX
else
ent.animation.curranim = g_ANIM_IDLE_R
ent.body.vx *= 0.75 -- 0.8, 0.9, = 0
if (-ent.body.vx<>ent.body.vx) < 0.001 then ent.body.vx = 0 end
end
-- IS ON FLOOR
elseif (ent.isfloorcontacts or
(ent.isfloorcontacts and ent.isladdercontacts)) and
not ent.isptpfcontacts and
not ent.ismvpfcontacts and
not ent.iswallcontacts
then
-- if ent.isplayer1 then print("isonfloor", dt) end
if ent.isleft and not ent.isright then -- LEFT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = -1
if ent.body.currdashtimer > 0 then
ent.body.vx -= ent.body.currspeed*ent.body.dashmultiplier
else
ent.body.vx = -ent.body.currspeed
end
end
elseif ent.isright and not ent.isleft then -- RIGHT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = 1
if ent.body.currdashtimer > 0 then
ent.body.vx += ent.body.currspeed*ent.body.dashmultiplier
else
ent.body.vx = ent.body.currspeed
end
end
else
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_IDLE_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.body.vx *= 0.75 -- 0.8, 0.9, = 0
end
if (-ent.body.vx<>ent.body.vx) < 0.001 then ent.body.vx = 0 end
end
if ent.body.currinputbuffer > 0 and not ent.isdown and not ent.wasup then -- UP
if ent.wasbadlyhurt > 0 then
-- cannot jump
else
ent.body.vy = -ent.body.currupspeed
ent.wasup = true
ent.body.currjumpcount = ent.body.jumpcount
ent.body.currinputbuffer = 0 -- prevents double jump when releasing up key
end
-- elseif ent.isdown and not ent.isup then -- DOWN
end
-- IS ON LADDER
elseif not ent.isfloorcontacts and
ent.isladdercontacts and
not ent.isptpfcontacts and
not ent.ismvpfcontacts and
not ent.iswallcontacts
then
-- if ent.isplayer1 then print("isladdercontacts", dt) end
if ent.isflyingnme then return end -- flying nmes don't collide with ladders
if ent.isleft and not ent.isright then -- LEFT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = -1
ent.body.vx = -ent.body.currspeed*0.5
end
elseif ent.isright and not ent.isleft then -- RIGHT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = 1
ent.body.vx = ent.body.currspeed*0.5
end
else
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_IDLE_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.body.vx *= 0.75 -- 0.8, 0.9, = 0
end
if (-ent.body.vx<>ent.body.vx) < 0.001 then ent.body.vx = 0 end
end
if ent.isup and not ent.isdown then -- UP
if ent.washurt > 0 or ent.wasbadlyhurt > 0 or ent.currlives <= 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 or ent.currlives <= 0 then
-- cannot move
else
ent.body.vy = -ent.body.currupspeed*0.2 -- magik XXX
ent.wasup = false -- allows jumping up off ladder
end
elseif ent.isdown and not ent.isup then -- DOWN
if ent.washurt > 0 or ent.wasbadlyhurt > 0 or ent.currlives <= 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 or ent.currlives <= 0 then
-- cannot move
else
ent.body.vy = ent.body.currupspeed*0.2 -- magik XXX
end
else
if ent.wasbadlyhurt > 0 or ent.currlives <= 0 then
ent.body.vy = ent.body.currupspeed -- fall off ladder
else
ent.body.vy = 0
end
end
ent.wasonladder = true
-- IS ON PTPF
elseif not ent.isfloorcontacts and
not ent.isladdercontacts and
ent.isptpfcontacts and
not ent.ismvpfcontacts and
not ent.iswallcontacts
then
-- if ent.isplayer1 then print("isptpfcontacts", dt) end
if ent.isleft and not ent.isright then -- LEFT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = -1
if ent.body.currdashtimer > 0 then
ent.body.vx -= ent.body.currspeed*ent.body.dashmultiplier
else
ent.body.vx = -ent.body.currspeed
end
end
elseif ent.isright and not ent.isleft then -- RIGHT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = 1
if ent.body.currdashtimer > 0 then
ent.body.vx += ent.body.currspeed*ent.body.dashmultiplier
else
ent.body.vx = ent.body.currspeed
end
end
else
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_IDLE_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.body.vx *= 0.75 -- 0.8, 0.9, = 0
end
if (-ent.body.vx<>ent.body.vx) < 0.001 then ent.body.vx = 0 end
end
if ent.body.currinputbuffer > 0 and not ent.isdown and not ent.wasup then -- UP
if ent.wasbadlyhurt > 0 then
-- cannot jump
else
ent.body.vy = -ent.body.currupspeed
ent.wasup = true
ent.body.currinputbuffer = 0 -- prevents double jump when releasing up key
end
elseif ent.isdown and not ent.isup and not ent.wasdown then -- DOWN
if ent.wasbadlyhurt > 0 then
-- cannot jump down
else
ent.body.vy = ent.body.currupspeed*0.1
ent.wasdown = true
end
end
-- IS ON MVPF
elseif not ent.isfloorcontacts and
not ent.isladdercontacts and
not ent.isptpfcontacts and
ent.ismvpfcontacts and
not ent.iswallcontacts
then -- also controlled in collisions
-- if ent.isplayer1 then print("ismvpfcontacts", dt) end
if ent.isleft and not ent.isright then -- LEFT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = -1
end
elseif ent.isright and not ent.isleft then -- RIGHT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_RUN_R
end
if ent.wasbadlyhurt > 0 then
ent.body.vx *= 0.1 -- cancel move! magik XXX
else
ent.flip = 1
end
else
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_IDLE_R
end
end
if ent.body.currinputbuffer > 0 and not ent.isdown and not ent.wasup then -- UP
if ent.wasbadlyhurt > 0 then
-- cannot jump
else
ent.body.vy = -ent.body.currupspeed
ent.wasup = true -- if set to true cannot jump!
ent.body.currinputbuffer = 0 -- prevents double jump when releasing up key
end
elseif ent.isdown and not ent.isup and not ent.wasdown then -- DOWN
if ent.wasbadlyhurt > 0 then
-- cannot jump down
else
ent.body.vy = ent.body.currupspeed*0.1
ent.wasdown = true
end
end
ent.wasonmvpf = true
-- IS ON WALL
elseif not ent.isfloorcontacts and
not ent.isladdercontacts and
not ent.isptpfcontacts and
not ent.ismvpfcontacts and
ent.iswallcontacts
then
-- if ent.isplayer1 then print("isonwall", dt) end
if ent.isleft and not ent.isright then -- LEFT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_WALL_IDLE_R
end
ent.flip = -1
ent.body.vx = -ent.body.currspeed
elseif ent.isright and not ent.isleft then -- RIGHT
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_WALL_IDLE_R
end
ent.flip = 1
ent.body.vx = ent.body.currspeed
else
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_WALL_DOWN_R
end
ent.body.vy = ent.body.currupspeed*0.25
end
if ent.isup and not ent.isdown then -- UP
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_WALL_UP_R
end
ent.body.vy = -ent.body.currupspeed*0.01
elseif ent.isdown and not ent.isup then -- DOWN
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
else ent.animation.curranim = g_ANIM_WALL_DOWN_R
end
ent.body.vy = ent.body.currupspeed*0.05
end
ent.wasonwall = true
-- IS ON SPRING
elseif ent.isspringcontacts then
-- if ent.isplayer1 then print("isspringcontacts", dt) end
-- IS IN THE AIR
else
-- if ent.isplayer1 then print("isintheair", dt) end
-- anims
if ent.isplayer1 and ent.currlives > 0 then
if ent.washurt > 0 or ent.wasbadlyhurt > 0 then -- animations in ent system
elseif ent.body.vy < 0 then ent.animation.curranim = g_ANIM_JUMPUP_R -- going UP
else ent.animation.curranim = g_ANIM_JUMPDOWN_R -- going DOWN
end
end
-- movements
if ent.isleft and not ent.isright then -- LEFT
ent.flip = -1
if ent.body.currdashtimer > 0 then
ent.body.vx -= ent.body.currspeed*ent.body.dashmultiplier
else
if ent.wasonwall then -- vx acceleration
ent.body.vx = -ent.body.currspeed*1.5 -- 2, magik XXX
else
ent.body.vx = -ent.body.currspeed
end
end
elseif ent.isright and not ent.isleft then -- RIGHT
ent.flip = 1
if ent.body.currdashtimer > 0 then
ent.body.vx += ent.body.currspeed*ent.body.dashmultiplier
else
if ent.wasonwall then -- vx acceleration
ent.body.vx = ent.body.currspeed*1.5 -- 2, magik XXX
else
ent.body.vx = ent.body.currspeed
end
end
else
ent.body.vx *= 0.9 -- 0.99, [0, 1], GAMEPLAY, some air friction, you choose!
end
if ent.isup and not ent.isdown and not ent.wasup
and ent.body.currcoyotetimer > 0 and ent.body.currjumpcount > 0 then -- UP
ent.wasup = true -- you can comment this line, GAMEPLAY WALLS JUMPING
ent.body.currcoyotetimer = 0
ent.body.currjumpcount -= 1
if ent.body.vy >= 0 then -- prevent double jump when fast pressing up!
ent.body.vy = -ent.body.currupspeed
end
if ent.wasonladder then -- attenuate ent jumping off on top of ladder
ent.body.vy *= 0.5
ent.wasonladder = false
end
elseif ent.isdown and not ent.isup and not ent.wasdown then -- DOWN
ent.wasdown = true -- ok
end
end
-- move & flip
ent.pos = vector(nextx, nexty)
ent.sprite:setPosition(ent.pos + vector(ent.collbox.w/2, -ent.h/2+ent.collbox.h))
-- if ent.animation then
ent.animation.bmp:setScale(ent.sx*ent.flip, ent.sy)
-- end
end
Code comments
- runs once on init and every game loop (process)
- affects only entities which have a collision box id (collbox) and a body id (we exclude some other entities)
- when an enemy Entity is off screen we don't process it to save some processing
- the collisionfilter tells cBump how entities interact with each other when they collide: "touch", "cross", "slide", "bounce"
- then we let cBump resolve the collision between the entities:
local goalx = ent.pos.x + ent.body.vx * dt
local goaly = ent.pos.y + ent.body.vy * dt
local nextx, nexty, collisions, len = self.bworld:move(ent, goalx, goaly, collisionfilter)
- once the collisions are resolved, we can instruct the Entity to perform certain tasks. For example, we can reset the Entity velocity, change the Entity state (isonfloor, isonwall, ...), ...
- cBump allows us to detect collisions from the top, left, right, bottom or from any directions
- now we can apply the "forces": the gravity and the entities movement (up, down, left, right)
- finally, depending on the state the Entity is in (isstepcontacts, isfloorcontacts, isladdercontacts, ...) we process the input (keyboard for the player1 and AI for the enemies) to control our player
- and we update the sprite position on the screen
Next?
That was a big one but it needed to be done. The last systems we will add are for the collectibles, doors, moving platforms and a couple more 😉. Don't worry they should be pretty short!
Prev.: Tuto tiny-ecs 2d platformer Part 9 Systems
Next: Tuto tiny-ecs 2d platformer Part 11 Systems 3
Tutorial - tiny-ecs 2d platformer
