ScaleGesture.LocalDeltaScale limitation about touchscript

[valyard]

Scale is multiplicative. This might be misleading but value of 1 is "no scale", 1.1 — 10% scaled up, 0.9 — 10% scaled down.

[avgritche]

That's the way i saw it, but the retreived value does not reflect the spacing between fingers..
I expected something like: "Current_FingerDistance / GestureStart_FingersDistance" that could be done in a slow & precise move (currently used to control the zoom of a camera).

[valyard]

This is delta value. You should keep all the previous values to calculate current absolute scale.

currentScale *= delta;

It's not that simple with "start finger distance" as you pointed out because you can start with one fingers and end the gesture holding other ones.

[avgritche]

From Unity documentation : "Contains local delta scale when gesture is recognized. Value is between 0 and +infinity, where 1 is no scale, 0.5 is scaled in half, 2 scaled twice."

It sound like a value i could directly use ?
So it's not clear what you mean by storing each deltas.

The problem is that i don't get such values for it (debug.print)..
1.0 - or close on gesture recognition = no scale
0.8 - when fingers are totally close from others, + relativly linear move from "no scale" position = useable.
1.01 - when finger are as far as possible from center, + unuseable move from "no scale" position (from 1.0 to 1.12 then to 1.01) = unuseable.

ps : The rotation (the hardest one i guess) work as a charm.. i wont bother you with this one ;)

[valyard]

No, this is delta value from previous frame.
It is like (distance between fingers this frame) / (distance between fingers last frame).

[avgritche]

My goal is not to argue, but to make it work in my project and help you improve you'r lib meanwhile.. so i need to describe the value as it is.
What i obtain from ScaleGesture.LocalDeltaScale is like : Current_FingerDistance / GestureStart_FingersDistance.
It may be different from what you intend/got, for a weird reason.. but that's bugs rules, and that's why i'm here.

[valyard]

Sorry I lost track of what you actually want.
Do you want LocalDeltaScale to be equal to (current finger distance) / (start finger distance), right?
If so, it's not possible. LocalDeltaScale = (current finger distance) / (finger distance last frame).
So, once again, to get absolute scale value you need to store LocalDeltaScale each frame like this:

absoluteScale *= gesture.LocalDeltaScale;

absoluteScale variable will contain what you want.

[avgritche]

I've done the zoom & pan i needed directly using TouchManager.Touches.. and the rotation using your events.
So this discussion now only intend to bring feedback to you, as this lib is a nice gift that helped me a lot.

using ScaleGesture.LocalDeltaScale :

• if put some fingers and scale then down a bit, i obtain 0.99 (nearly 1.0 - triggering) : it's ok.
• if i scale then down at maximum, i obtain 0.8 (never 0.5), but the localdeltascale reflect my finger spacing : it's ok.
• if i maintain the same position, i still obtain 0.8 (so it does not sound like a delta) : but it's still ok.

then

• if i try to scale up.. i can go back from 0.8 to 1.0 with no problem.. but when scaling up, the values are non lineary linked to my fingers spacing, that's where my problem is. While i increase the finger spacing, it move from 1.0 to 1.1, then to 1.01.. i never can reach 1.5 or even 2.0.

In short : Scale down work nicely, scale up does not work.. for me.

ps : i'm french, so sorry if my english does not help understanding and/or does not reflect the friendly feeling.

[valyard]

This doesn't sound like normal behavior. Do you have a test project you could send me to test?

[avgritche]

Preparing the sample made it clearer :
You where right from start, "absoluteScale *= gesture.LocalDeltaScale;" is perfect for this need.

So sorry for this long missunderstanding, and thanks for your patience..

Regards,
Alain.

[valyard]

Good to know that you figured this out.