Shooting arrow

Solar2D General Questions/Discussion
#21

Dssi thanks for the answer.

I’ve applied those lines to my app (just in case somebody wants to use it too, its math.cos, math.sin on the local xForce,yForce and magicBullet:applyForce) but whenever i press, the arrow goes always a little bit to the bottom of the screen, and when I press in the upper section of the screen ( the arrow is initialized in the middle), the arrow goes to the middle, cant get past it. I know it might be something about a negative value but i don’t know what to change to do it. 

Tell me if you understand what i just said, if not i can make a simple graphic.

Thanks again

#22

 I was in a rush so I may have left some more things out

above all I was foolish I didn’t ask where you will be initializing the arrow haha…

there are two things I missed

first you should turn Off gravity after you call physics.start()

by typing

physics.setGravity(0,0)

and I forgot to tell you how to set the initial location

so this is a script I tested and I gaurantee it  works

local physics = require(“physics”)

physics.start()
physics.setGravity(0,0)

local bulletGroup = display.newGroup()
 

local function touched(event)
if event.phase ==“began” then
local magicBullet = display.newImage(“image.png”)
local startX = 123 – startlocaations

local startY = 123

physics.addBody(magicBullet,“dynamic”)

**magicBullet.x = startX
magicBullet.y = startY
local atanVal = math.atan2(event.y - startX,event.x - startY)
local xForce,yForce = math.cos(atanVal)*(speed), math.sin(atanVal)*( speed )

magicBullet:applyForce(xForce,yForce,magicBullet.x,magicBullet.y)**

bulletGroup:insert(magicBullet)  – i reccomend you do this so you’ll be able to delete
end
end

Runtime:addEventListener(“touch”,touched)

I just started answering questions so my replies are pretty lame …sorry haha… :D  :D 

#23

Thanks a lot! added it inside a for loop and it worked!

Only thing i’ve noticed is that if you want to use a different position where startX =/ startY you have to use 

local atanVal = math.atan2(event.y - startX,event.x - startY)

instead of 

local atanVal = math.atan2(event.y - startY,event.x - startX)

Thanks for all the help, i’ll totally need to re-read all those math books haha…

#24

I would recommend:

http://www.amazon.com/Mathematics-Game-Developers-Development/dp/159200038X

or

http://www.amazon.com/Beginning-Math-Physics-Game-Programmers/dp/0735713901/ref=pd_sim_b_1

#25

I tested this chunk of code for my self and it was very nice

One thing I would like to implement is that the arrow follows the sinus curve so it looks more natural

so it kinda points down when it false to the ground

and I´m also one of those coders who says “I wish I didn´t sleep through the math lessons at school”

I started with:

physics.setGravity(0,4) --so it falls down after a while

local speed = -20 --this could be calculated on the length between self and target

magicBullet.isFixedRotation = false  --but after this I got lost

#26

hmm, that’s strange it may have something to do with the view My scripts are based on vertical so , anyway gladit works

#27

I was thinking like this:

http://snag.gy/TB2xj.jpg

#28

Anyone?

I was thinking like this:
http://snag.gy/TB2xj.jpg

#29

Good timing, i’m having the same problem…

#30

Bumping this thread.

#31

Hi I think this is what you guys are looking for.

http://developer.coronalabs.com/code/arrow-basics

Cheers

#32

Anyone?

I was thinking like this:
http://snag.gy/TB2xj.jpg

#33

Good timing, i’m having the same problem…

#34

Bumping this thread.

#35

Hi I think this is what you guys are looking for.

http://developer.coronalabs.com/code/arrow-basics

Cheers