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DS development > Sensitivity of touchscreen

#151388 - Sweater Fish Deluxe - Mon Feb 25, 2008 12:40 am

Is there a way to adjust the sensitivity of the touchscreen? I find that the larger the area you're touching is, the harder you have to press to get it to regsiter any touch at all.

The commercial game Trace Memory has a section where you have to press your thumb to the screen and go through a fake fingerprint scan. Now I haven't played Trace Memory recently, but I did play it once and I remember that section, but I don't recall having to really jam my thumb into the screen the way I do with the current fake thumbprint scanner I'm working on. I have to press so hard that the colors on the screen start distorting (which looks cool, I suppose, but doesn't seem safe).

I just found Jesse's tutorial posted to this forum a while back on how to detect the pressure of a touch and I'm thinking that maybe the Z values can somehow be used to detect the touch sooner than the X and Y values, so I'll mess around with that some when I get home, but I wondered if anyone has any other ideas.


...word is bondage...

#151395 - nanou - Mon Feb 25, 2008 6:10 am

That sounds like a good start. I haven't checked into it yet, but I've been noticing that commercial games, with a few exceptions, seem to have a minimum pressure threshold that requires more force than colors or something. It's probably part of the official SDK or something, but it seems reasonable that you could do such a thing.

An anecdote: when playing Hotel Dusk there was a part where the player has to flip two breakers at once. The way I solved it was by sliding two fingers up the screen. After, I supposed that you could have just drawn a line up in between them, but I never did go back and check. Is it possible that they checked the activated touch area in a similar fashion to the pressure sensitivity hack? If so, it means the system will report on most if not all of the screen area at once. (IIRC it draws rectangles... is that right?)
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- nanou

#151450 - Sweater Fish Deluxe - Tue Feb 26, 2008 6:27 pm

The Z values don't seem to update any sooner than the X and Y values, but that may be because of the way libnds is handling the touchscreen. I don't know if it matter enough for me to keep digging into this, though.

Playing around with those Z values last night was a lot of fun, though. It gives me some great ideas for gimmicky uses of the touchscreen. Differences in calibration from one DS to another aside, it seems like it would be perfectly possible to have the player touch one specific part of the screen and then touch another and be able to tell with some precision where the second touch ocurred. This may be the idea behind the section of Hotel Dusk that you mentioned.


...word is bondage...

#151457 - nanou - Wed Feb 27, 2008 1:56 am

Seems reasonable that you could work out two points based on an accurate point sample followed by an inaccurate one. Point #2 is point #1 h,v mirrored around the second sampled position. You just have to know that all of this is going on, and I guess that's what the Z value is for.

I'll definitely be checking it out in detail later after I've got 3D cornered.
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- nanou