Hi everyone. I need some help. Somehow I forgot how to use the “collide” function. Could I please get some help? Btw I wouldn’t be posting if I could find an e book on it or something. That’s why I ask, Becuase I can’t get any other help. Thanks guys!
Just use the Codea reference, (the eye in-project).
See the discussion What's the logic of contact bodyA and bodyB a few discussions down.
@MattthewLXXIII I have tried, but it’s not enough
And what I mean is ~physics.contact~ where to put it, and how it works. 
@LL_Phoenix456, what are you trying to do? And which part is confusing of the contact reference? Have you tried looking at the physics lab demo? I found it quite helpful.
I’m trying to make an asteroid dodging game and I forgot how to check for certain collisions after scanning through a table (the table is asteroids)
@LL_Pheonix456 you could do something like:
function collide(c)
for i,v in pairs(asteroids) do
if (c.bodyA == v.body and c.bodyB == player.body) or (c.bodyB == v.body and c.bodyA == player.body) then
print("DIE")
end
end
end
@MattthewLXXIII And what would I change the v.bodyA, v.body and c.body to?
@LL_Phoenix456 Will anything here help explain what you need to do.
displayMode(FULLSCREEN)
function setup()
hit=6
e=physics.body(CHAIN,true,vec2(0,0),vec2(0,HEIGHT),
vec2(WIDTH,HEIGHT),vec2(WIDTH,0))
e.info="edge"
s=physics.body(CIRCLE,40)
s.x=WIDTH/2
s.y=HEIGHT/2
s.gravityScale=0
s.restitution=1
s.info="ship"
ast={}
for z=1,10 do
a=physics.body(CIRCLE,30)
a.x=math.random(WIDTH)
a.y=math.random(HEIGHT)
a.linearVelocity=vec2(math.random(-300,300),math.random(-300,300))
a.gravityScale=0
a.restitution=1
a.info="ast"
a.friction=.1
table.insert(ast,a)
end
end
function draw()
background(0)
fill(255)
pushMatrix()
translate(s.x,s.y)
rotate(s.angle)
if hit<5 then
hit=hit+1
sprite("Tyrian Remastered:Explosion Huge",0,0,hit*20)
else
sprite("Space Art:Red Ship",0,0)
end
translate()
popMatrix()
for a,b in pairs(ast) do
pushMatrix()
translate(b.x,b.y)
rotate(b.angle)
sprite("Space Art:Asteroid Large",0,0,80)
translate()
popMatrix()
end
end
function collide(c)
if c.bodyA.info=="ast" and c.bodyB.info=="ship" or
c.bodyA.info=="ship" and c.bodyB.info=="ast" then
hit=0
end
end
@dave1707 What’s the deal with bodyA and bodyB? I tried implementing it and it didn’t work
I don’t get it. I’m trying to make it so if the player collides with an asteroid, it does something. Not if anything collides with anything.
@LL_Phoenix456 Are you saying you just want the asteroids to collide with the ship (player) and nothing else. In other words, the asteroids can come from any direction off screen, pass thru the screen area in a straight line, then go off the screen. They don’t collide with each other, only the ship. If that’s the case, you don’t need to use the collide function, which is for physics objects. You can just use a simple function that calculates the distance between each asteroid and the ship and if they’re below a certain distance, there’s a collision. Is that what you’re trying to do. A lot of times, the hard part is trying to understand what needs to be done, not the coding to do it.
@dave1707 Yep. That’s exactly right.
@LL_Phoenix456 Are you looking for something like this. Move your finger around the screen to move the ship.
displayMode(FULLSCREEN)
supportedOrientations(LANDSCAPE_ANY)
function setup()
hits=0
et=os.clock()
ast={}
for z=1,30 do
x=WIDTH+math.random(400) -- x position
y=math.random(HEIGHT) -- y position
z=math.random(1,10) -- speed
w=math.random(1,2) -- type
table.insert(ast,vec4(x,y,z,w))
end
shx=WIDTH/2
shy=HEIGHT/2
dx,dy=0,0
end
function draw()
background(0)
for a,b in pairs(ast) do
if b.w==1 then
sprite("Space Art:Asteroid Large",b.x,b.y)
else
sprite("Space Art:Asteroid Small",b.x,b.y)
end
b.x=b.x-b.z
if b.x<-50 then
b.x=WIDTH+math.random(200)
b.y=math.random(HEIGHT)
end
checkCollision()
end
pushMatrix()
translate(shx+dx,shy+dy)
rotate(270)
if hit then
sprite("Tyrian Remastered:Explosion Huge",0,0)
else
sprite("Space Art:Red Ship Icon",0,0)
end
popMatrix()
fill(255)
text(string.format("Time %.1f Hits %d",os.clock()-et,hits),WIDTH/2,HEIGHT-20)
end
function checkCollision()
hit=false
for a,b in pairs(ast) do
v1=vec2(b.x,b.y)
d=v1:dist(vec2(shx+dx,shy+dy))
if b.w==1 then
if d<60 then
hit=true
if clear then
hits=hits+1
end
clear=false
end
elseif d<20 then
hit=true
if clear then
hits=hits+1
end
clear=false
end
end
if not hit then
clear=true
end
end
function touched(t)
if t.state==MOVING then
dx=dx+t.deltaX
dy=dy+t.deltaY
end
end