Objects selectable only on visible part

[ErDetEnAnd?]

Hello again.

Selection works on polygons, so if a selectable object carries a (partial) transparent texture, it would also be selected when clicked on the invisible part. Is there some kind of solution for this?

Regards.

[EgonOlsen]

In theory, it should be possible to do something like this:

• determine the picking point in camera space
• transform that point into object space
• transform that point into texture space
• perform a look up on the texture if that point is transparent or not

However, that is quite complex to do. What exactly do you need this for? Maybe there's a simpler solution that covers your case.

[ErDetEnAnd?]

In my program billboards sometimes work as labels which should be selectable. The label surrounds some text, and fits hardly into a 2^x texture size. So the transparent part of the texture (outside the label) becomes selectable :-(

[EgonOlsen]

But why are you using the whole 2^x pixels of the texture for texturing the label if only a part of it is actually used? Maybe a screen shot helps to understand better what you are doing.

[ErDetEnAnd?]

You sugguest jPCT to autoscale it?

[EgonOlsen]

You sugguest jPCT to autoscale it?

Autoscale what? What i meant was, that there should be no parts of the texture used for the label quad except for the label itself. It's difficult to explain...that's why i was asking for a picture to see if we are talking about the same thing...

[paulscode]

Depending on what you are using this for, you might be able to make the polys smaller and change your UV coordinates so that only the non-transparent part of the texture is drawn.

[EgonOlsen]

Depending on what you are using this for, you might be able to make the polys smaller and change your UV coordinates so that only the non-transparent part of the texture is drawn.

That's what i tried to describe and wasn't really able to...