How do you calculate shooting vector [Solved]

[axehigh]

I am making a shoot'em up game, where the enemy is shooting at the player (or a target coordinate)

How do you make the bullet fly in a straight line at the player, when f.ex the shot source coordinates are at 300,300 and the player is at coordinates 500,500?

[raidho36]

Math function "atan2" calculates angle based on coordinates to the target (from 0,0).

[pgimeno]

You don't need atan2 for that though. You can use the vector length formula:

Code: Select all

local function vector_length(x, y)
  return math.sqrt(x^2+y^2)
end

Now, the vector from the enemy to the player is given by (player - enemy), that's player.x - enemy.x, player.y - enemy.y. Divide that by its length:

Code: Select all

local vx = player.x - enemy.x
local vy = player.y - enemy.y
local vlen = vector_length(vx, vy)
vx = vx / vlen
vy = vy / vlen

and you have a unit vector pointing from the enemy to the player. Multiply that by dt times the bullet speed, and voilà.

[axehigh]

Thanks!

Worked like a charm