Multitouch as a theory.

Discussion in 'NDS - Emulation and Homebrew' started by DrOctapu, May 30, 2009.

  1. DrOctapu

    DrOctapu Magnificent Bastard

    Dec 23, 2008
    United States

    The above link is an example of multitouch hacked on to a single-pointer touch input device.
    Theoretically, this method could be applied to the DS using colors' (the painting app) ability to read pressure. You may have noticed in calibration, that you can get it down to around 20 (a number nearly impossible to reach without breaking the screen/damaging it), by simply putting down 2 styli on the point that it callibrates on. The ds's x and y change rapidly when there are two points, depending on the pressure of each. This could be solved by snapping it to a grid, and having it go to the nearest area, then converting the x and y data given to the ds to the locations of the two points on the ds screen. I believe the creator of Dphone made something of the sort to emulate the iphone's image zooming/rotation.

    Could this method be used on the ds? Or is it to complicated, and if it could be done no one would bother to code it?
  2. Uruha

    Uruha GBAtemp Regular

    Aug 9, 2008
    United States
    actually i remember seeing a multi touch for the DS. it is possible because it has been done.
    i didnt no it read pressure though!
  3. jesterscourt

    jesterscourt Not Brad.

    Jan 3, 2007
    United States
    Pressure sensitivity can vary quite a bit on the DS, just check out the calibration feature in Colors with 2 different DSs and see your result.
  4. Skyline969

    Skyline969 MENUdo Afficionado

    Nov 18, 2008
    Multi-touch has been done before on the DS. At least, I've seen it in one game - Hotel Dusk: Room 215. When you have to flip two breakers in a box at the same time, you touch them at the same time. It may have been for a brief second that it was used, but that's multi-touch, no?
  5. fgghjjkll

    fgghjjkll GBATemp MegaMan

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    Jul 7, 2008
    r u serious?
    its possible?
    but dphone doesnt have multi touch
  6. SifJar

    SifJar Not a pirate

    Apr 4, 2009
    sorry to break it to you guys, but i dont think this is really practical. the "multitouch" in hotel dusk works by realizing from the pressure that there are two touches, and taking a midpoint of them, which is all the DS gets, a touch at the midpoint of the touches with double pressure, and works out if thats halfway between the points needed to be touched. And the multi-touch homebrew that exists works in a similar way. it calculates that there are two styli/fingers on screen and adjusts accordingly. It just knows there ARE two touches, not WHERE they are. It only knows the midpoint between them. Soz guys

    EDIT: And DPhone DOES have multitouch in the picture viewer. But i can't get it to view pictures personally.
  7. OneMichael

    OneMichael Advanced Member

    Nov 27, 2008
    Manitoba, Canada
    It's been discussed before, with the general conclusion being that it was just too varying between systems. Until a couple years ago, even single-touch was hard to pin down.

    The touch screen is an analog system called Resistive Touch which, as far as my knowledge goes, retrieves the X and Y values by measuring the voltage flowing through a connection between its resistive layers, averaged to the voltage gradient.

    If you press a larger space, there's more voltage. If you press harder, there's more voltage. I could imagine getting it to work in one dimension, but any more than that would require guesswork, especially if the two points are closer together. As far as I know the only inputs you can get from that screen are average x/y co-ordinates and pressure. If you calibrated first for a single stylus and then for two styli at the same time, you could set a baseline which would tell you if someone was using two styli, and perhaps also how far apart they are. I would imagine a touch to be like a circle; a small dot if you use one stylus at one point, a smallish circle if you used a finger, and a large circle if you used multitouch.

    I could be horribly wrong, but what I gather from that is the conclusion that you could only really guess at where the styli are, and it would be horribly inaccurate.
  8. jan777

    jan777 motion control..? srsly? so 2008. 3DS is teh bombz

    Jan 4, 2008
    also in that master of illusion game, where you press one finger and another person presses hers then it calculates the love between you

    but i suppose that its the midpoint thingy
  9. Dwight

    Dwight Gawb. Gawb Bluth.

    Aug 14, 2008
    United States
    Washington State
    Well press where you think the midpoint is and see if it works.