Need help to smoothly scroll camera by dragging on mobile

Author

Message

IBOL

Retired Moderator

20

Years of Service

User Offline

Joined: 30th Mar 2004

Location: @IBOL17

Posted: 31st May 2017 03:57

Link

OK, so i want to be able to drag the mobile UI up and down with a finger.

The game is heavy on tapping, it's pretty much ALL UI.

Problem is, if you tap your fingers quickly in multiple places, the screen jerks up and down rapidly.
Run my sample code, and broadcast to a mobile device, and tap 2 fingers back and forth, to see what i mean.

So what i need is a way to ignore those kind of taps, but still allowing dragging.

HALP?!

+ Code Snippet

  s=1
 for t=-5 to 15
	 inc s
	 createsprite(s,0)
	 setspritesize(s,500,200)
	 setspriteposition(s,random(0,5)*20,t*300)
 next t
	
	SetViewZoomMode(1)
	
	Yoff=0
	
	do
		
` bad screen drag thing:		

	if GetPointerState()>0	
		if oldy<>0
			dy=(oldy-getpointery())
			Yoff=Yoff+dy
			SetViewOffset(0,Yoff)
			oldy=getpointery()
		else
			 oldy=getpointery()
		endif
	else
		oldy=0
	endif		
		
` END bad screen drag
		
		SetViewOffset(0,Yoff)
		
		sync()
	loop

Thanks,

Bob

http://ibology.org/

Back to top

Profile PM Email Website

blink0k

Moderator

11

Years of Service

User Offline

Joined: 22nd Feb 2013

Location: the land of oz

Posted: 31st May 2017 07:38

Link

Maybe use this multi touch technique to detect when there is more than one touch event

Back to top

Profile PM

IBOL

Retired Moderator

20

Years of Service

User Offline

Joined: 30th Mar 2004

Location: @IBOL17

Posted: 31st May 2017 21:34

Link

i don't see off the top of my head how to apply that to my situation, but thanks.

http://ibology.org/

Back to top

Profile PM Email Website

Mobiius

Valued Member

21

Years of Service

User Offline

Joined: 27th Feb 2003

Location: The Cold North

Posted: 1st Jun 2017 09:12

Link

Quote: "i don't see off the top of my head how to apply that to my situation, but thanks."

Require two fingers to drag instead of the one.
I use this technique in one of my unfinished projects. a single finger will rotate the camera, two fingers will move the camera.

Signature removed by mod because it's larger than 600x120... please resize and try again.

Back to top

Profile PM Email Website

29 games

19

Years of Service

User Offline

Joined: 23rd Nov 2005

Location: not entirely sure

Posted: 1st Jun 2017 21:36

Link

I think in this case you don't necessarily need to use multiple touch events, you just need to use the GetRawTouch... commands to detect whether the player has tapped or swiped.

This simple example shows how to do the swipe to move a sprite:

+ Code Snippet

SetVirtualResolution(800,480)

// create and size a sprite
createSprite(1,0)
SetSpriteSize(1,40,40)

// position of the sprite
xpos = 400
ypos = 240

do

    // capture touch event
    touch = GetRawFirstTouchEvent(1)

    // get all the basic information about the touch events
    touch_type = GetRawTouchType(touch)
    touch_xs = GetRawTouchStartX(touch)
    touch_xc = GetRawTouchCurrentX(touch)
    touch_xl = GetRawTouchLastX(touch)

    // if touch is drag event then move the sprite
    if touch_type = 3
        xpos = xpos + (touch_xc - touch_xl)
    endif

    // position the sprite
    SetSpritePositionByOffset(1,xpos,ypos)

    print("drag finger left and right across screen")

    sync()

loop

To actually select something off the menu, you'll need to check if the RawTouchType is a 1 (ie screen is pressed then release within 1 second) and then use the GetRawTouchStartX() and GetRawTouchStartY() values to detect collision with the sprite.

Hover Car Race Challenge! - available now on Google Play
Invaders of the 29th Dimension - available now on Google Play
Find me on indieDB

Back to top

Profile PM Email

IBOL

Retired Moderator

20

Years of Service

User Offline

Joined: 30th Mar 2004

Location: @IBOL17

Posted: 2nd Jun 2017 15:20

Link

OK, so,

thanks all.

Using a combination of the ideas posted here, i was able to make the system differentiate between multiple rapid taps and a screen drag.

it comes down to detecting all touch events during the loop, processing them individually.
Then, when the system thinks it's found a "drag" event, we check that event's length
IF GetRawTouchTime(index)>0.2
and if it's appropriately long, execute the drag.

i can now tap on 4 different points with basically no problem, and drag the screen around when necessary.

regarding "two fingers to drag",
i agree that does work,
but i find that when i try to make users do something in a new way, they tend to rebel against it.
people expect to be able to move the screen with a single finger.
But given a novel-enough game, i think most would be ok with it.

http://ibology.org/

Back to top

Profile PM Email Website

Sorry your browser is not supported!

AppGameKit Classic Chat / Need help to smoothly scroll camera by dragging on mobile