So I'm trying to make a projectile move in a sideways figure eight motion without having to use paths (please don't ask why), but for some reasons, I never can seem to get the projectile movement right... Create Event: [code]/* Movemement */ parent = 0; sinewave = 0; hortime = 5; hordir = 1;[/code] Step Event: [code]if (hordir = -1 && hortime > -10){ hortime += -0.5; } else if (hordir = -1 && hortime <= -10){ hordir = 1; } else if (hordir = 1 && hortime < 10){ hortime += 0.5; } else if (hordir = 1 && hortime >= 10){ hordir = -1; } sinewave += 5; y = ystart+lengthdir_y(40,sinewave); hspeed = -image_xscale*(hortime/2);[/code] Anyone knows what I'm doing wrong? I would be glad if someone could help me there. Thanks in advance!

[syntax=gml]wave = (wave + 0.2) % (4 * pi); ref_x += hspeed; x = ref_x + cos(wave * 0.5) * 128; y = ystart + sin(wave) * 128;[/syntax] [spoiler][img]http://i.imgur.com/ILPk948.gif[/img][/spoiler] Is this what you want?

Almost, but not quite. It was supossed to go back and forth and, like, literally draw a sideways figure eight. That might sound weird as a projectile, but don't worry, it all will make sense eventually. :3

Ah, in that case just remove the hspeed part and replace ref_x with xstart or something.

Thanks. Never thought Game Maker had proper sin/cos functions tbh, so I was searching for ways of emulating it... :whoops:

Pretty much all programming languages (including GML) have trigonometric functions.

lengthdir_x and lengthdir_y are basically just alternate versions to sin and cos, too. lengthdir_x(len, dir) is the same as cos(degtorad(dir)) * len lengthdir_y(len, dir) is the same as -sin(degtorad(dir)) * len Correct me if I messed up the maths

If you just made a perfect figure eight movement, then you could use [code]x += 1;[/code] to get the net movement without complex maths.