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.

Newcomers AppGameKit Corner / [Answered]Associating physics with a drawn line.

Author
Message
rfwarrior
10
Years of Service
User Offline
Joined: 13th Jan 2015
Location:
Posted: 13th Jan 2015 20:17
Link
Hi,

I'm a professional programmer by trade, but new to AppGameKit and so far I'm loving it.

I've dabbled with cocos2d and in that was able to easily add physics to a line (e.g allowing for collision etc).

I'm writing my first app where a user draws a freehand line (this is actually made up of a number of short lines, the lines can be at any angle. (and was based on a snippet of code I saw on this forum). They can draw curves loops etc.

Now I want to essentially create a box2d edge (is that a polygon with just two points ) for each segment of the line.


All I can see is how to create a polygon related to a sprite. Would I have to create a sprite for each line segment, a 1 pixel width rectangle of the length of the line segment and rotate it to the right angle of the line to achieve this?

If that's the way I have to go I will but I'm guessing (and hoping) there is an easier way to do this.

By the way - I am loving AppGameKit, a fantastic product and I can't wait to get my teeth into it further.
Back to top
Profile PM
BatVink
Moderator
22
Years of Service
User Offline
Joined: 4th Apr 2003
Location: Gods own County, UK
Posted: 13th Jan 2015 21:22
Link
Quote: "All I can see is how to create a polygon related to a sprite. Would I have to create a sprite for each line segment, a 1 pixel width rectangle of the length of the line segment and rotate it to the right angle of the line to achieve this?"


In a word, yes. Then you would add physics joints to hold it all together. Or if the lines don't move, they can be static objects with no joints.

It's been a while since I used physics, but I think edges are available in DBPro and not AGK.

Quidquid latine dictum sit, altum sonatur
Back to top
Profile PM Email
baxslash
Valued Member
Bronze Codemaster
18
Years of Service
User Offline
Joined: 26th Dec 2006
Location: Duffield
Posted: 14th Jan 2015 09:18
Link
Actually I haven't tried this but you can set a polygon shape with a minimum of 2 points using SetSpriteShapePolygon. It might be possible to create an edge that way.

You could then use AddSpriteShapePolygon to add additional lines to a single sprite.


Using AppGameKit V2 Tier 1
Back to top
Profile PM Email
rfwarrior
10
Years of Service
User Offline
Joined: 13th Jan 2015
Location:
Posted: 15th Jan 2015 23:50
Link
Tried a load of things, finally got it working.

I created and rotated sprites for the lines and it now behaves as it should.

Thanks for the help.

I would have set the post title to Answered but couldn't figure out how.
Back to top
Profile PM
baxslash
Valued Member
Bronze Codemaster
18
Years of Service
User Offline
Joined: 26th Dec 2006
Location: Duffield
Posted: 16th Jan 2015 21:22 Edited at: 16th Jan 2015 21:23
Link
Glad you got something working, you can't change the title once it's set. Only a MOD can do that and it seems they already have...


Using AppGameKit V2 Tier 1
Back to top
Profile PM Email
BatVink
Moderator
22
Years of Service
User Offline
Joined: 4th Apr 2003
Location: Gods own County, UK
Posted: 19th Jan 2015 12:35
Link
Did you do it with 2 points, or did it need more?

Quidquid latine dictum sit, altum sonatur
Back to top
Profile PM Email
rfwarrior
10
Years of Service
User Offline
Joined: 13th Jan 2015
Location:
Posted: 19th Jan 2015 19:49
Link
Hi BatVink,

I create multiple sprite lines as the pointer changes position.

I actually found the sprite line drawing routine somewhere on these forums (my version was screwing up with atanfull angles).
Then added physics to the sprites created.

Worked really well.
Back to top
Profile PM
rfwarrior
10
Years of Service
User Offline
Joined: 13th Jan 2015
Location:
Posted: 19th Jan 2015 21:07
Link
I drew a line (using sprites) from the last pointer position to the current one.

This results in a set of lines. which I added physics to as I went along.

Found a sprite line drawing routine on here - I was on the right track but my use of atanfull to get the angle was incorrect.
Back to top
Profile PM
BatVink
Moderator
22
Years of Service
User Offline
Joined: 4th Apr 2003
Location: Gods own County, UK
Posted: 20th Jan 2015 13:12
Link
My bad question. Are the physics shapes made of 2 points, or more than 2 points?

Quidquid latine dictum sit, altum sonatur
Back to top
Profile PM Email
rfwarrior
10
Years of Service
User Offline
Joined: 13th Jan 2015
Location:
Posted: 23rd Jan 2015 00:57
Link
The lines I am drawing have a width of 8. So each line is more like a rectangle so 4 points physics shape.

(sorry I didn't reply sooner. Didn't see you'd asked a question)
Back to top
Profile PM
BatVink
Moderator
22
Years of Service
User Offline
Joined: 4th Apr 2003
Location: Gods own County, UK
Posted: 23rd Jan 2015 09:44
Link
Thanks. I might try Baxslash' idea, it could be very useful for 'one-sided' physics. For example a Pong paddle the ball passes through from behind.

Quidquid latine dictum sit, altum sonatur
Back to top
Profile PM Email
Back to top

Login to post a reply

Server time is: 2025-05-13 08:46:57
Your offset time is: 2025-05-13 08:46:57