Sorry your browser is not supported!

You are using an outdated browser that does not support modern web technologies, in order to use this site please update to a new browser.

Browsers supported include Chrome, FireFox, Safari, Opera, Internet Explorer 10+ or Microsoft Edge.

AppGameKit Classic Chat / Trouble with SetSpritePhysicsVelocity

Author
Message
basicFanatic
6
Years of Service
User Offline
Joined: 7th Jun 2017
Location:
Posted: 23rd Jul 2020 12:41
Link

So I have this nice bit of code:

SetSpritePhysicsVelocity(Bullets[Bullets.length].SID, cos(0.0)*50.0, sin(0.0)*50.0)

According to my understanding, 0.0 should make it move at 0 degrees, that is, straight up. But it moves to the right. What am I missing?

Maybe 0 degrees means three o'clock instead?
Back to top
Profile PM
Bengismo
6
Years of Service
User Offline
Joined: 20th Nov 2017
Location: Yorkshire, England
Posted: 23rd Jul 2020 12:58 Edited at: 23rd Jul 2020 12:59
Link
Trigonometry...

Cos(0.0) = 1
Sin(0.0) = 0

So your code is setting the sprite speed to be x=50, y=0 which is "3oclock"


If you want 0 degrees to upwards (and any angle used to be clockwise) then use

SetSpritePhysicsVelocity(Bullets[Bullets.length].SID, sin(Angle#)*50.0, -cos(Angle#)*50.0 )


If your angle is always going to be 0 then:

SetSpritePhysicsVelocity(Bullets[Bullets.length].SID, 0, -50.0 )
Back to top
Profile PM
basicFanatic
6
Years of Service
User Offline
Joined: 7th Jun 2017
Location:
Posted: 23rd Jul 2020 13:46
Link
Thanks, it works! cos/sin is one of those things I never really figured out. However, I don't want to make up new standards just because. It was only that I guessed that 0 degree was up because that felt most natural. But in page 598 of the guide, it is suggested that 3 o'clock is the default angle, going clockwise from there. So I just reworked my code from that, and it run fine now. (despite my broken physics, but whatevs)
Back to top
Profile PM
PSY
Developer
7
Years of Service
User Offline
Joined: 3rd Jul 2016
Location: Laniakea Supercluster
Posted: 23rd Jul 2020 16:02
Link
@basicFanatic

Quote: "cos/sin is one of those things I never really figured out"

I strongly recommend to read up on how cos and sin work and what they really are.

There are a lot of good tutorials/videos about these, and it's pretty easy stuff ( it really is ).

You can thank me later


PSY LABS Games
Coders don't die, they just gosub without return
Back to top
Profile PM Website
Back to top

Login to post a reply

Server time is: 2024-04-18 13:24:13
Your offset time is: 2024-04-18 13:24:13