[X3D-Public] What is the behavior of Touch/Drag sensors when occluded?

[Dave A]

Thanks Sergey and Michalis!

On 5/12/2012 2:13 AM, Bederov, Sergey wrote:
> Hello Dave,
>
> Handling of transparent textures is explicitly defined in specification:
>
> http://www.web3d.org/x3d/specifications/OLD/ISO-IEC-19775-X3DAbstractSpecification/Part01/components/pointingsensor.html#OverviewOfPointingDeviceSensors
>
> "The appearance properties of the geometry do not affect activation of the sensor. In particular, transparent materials or textures shall be treated as opaque with respect to activation of pointing-device sensors."
>
> Though, there is some ambiguity about shapes without sensors:
>
> http://www.web3d.org/x3d/specifications/OLD/ISO-IEC-19775-X3DAbstractSpecification/Part01/components/pointingsensor.html#Activatingandmanipulating
>
> "In all cases the pointer is considered to be indicating a specific geometry when that geometry is intersected by the bearing. If the bearing intersects multiple sensors' geometries, only the sensor nearest to the pointer will be eligible for activation."
>
> In other words, if the ray intersects multiple shapes with sensors, the nearest one is picked; but it's not clear what to do if there is a shape without sensors and it happens to be the nearest one.
>
> Cortona3D Viewer (and, I believe, most VRML and X3D browsers) interpret it as "the geometry nearest to the pointer". First, the geometry nearest to the camera is determined; second, it is checked whether this geometry has any active sensors attached. If the nearest geometry doesn't have sensors, no sensors are activated.
>
> Probably the specification needs to be clarified?
>
>
>                                                       Sergey Bederov
>
>
>
>> -----Original Message-----
>> From: x3d-public-bounces at web3d.org [mailto:x3d-public-bounces at web3d.org] On
>> Behalf Of Dave A
>> Sent: Saturday, May 12, 2012 11:15 AM
>> To: x3d-public at web3d.org
>> Subject: [X3D-Public] What is the behavior of Touch/Drag sensors when
>> occluded?
>>
>> Let's say you have an object that has a TouchSensor on it. It happens to be
>> behind a (let's say) semi-transparent object. Maybe that material has a
>> texture that looks like chain-link fence or maybe it's a window.
>>
>> Should I be able to touch it?
>>
>> I don't see anything in the spec that really addresses this.
>>
>> What I would hope for in a knee-jerk way is, it would let me pick 'through'
>> transparent textures. But I realize this is a dicey proposition to make a
>> blanket rule.
>>
>> So my next thought is that it would let me pick through anything that
>> doesn't also have a sensor like that on it. But again, easy to find examples
>> of why that's not good.
>>
>> So ultimately, what I expect, is some sort of boolean or node or something
>> that says 'ignore for picking' or something to that effect.
>>
>> Anyone know if Contact has such an option?
>>
>> Dave A
>>
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