A google search for "Ray Intersection Tests" gives a number of
good links on how to do this. Also, Peter Shirley's book "Realistic
Ray Tracing" is a fantastic introduction to the subject. But I have
no example code on hand that could be used on Android.
-Anton
On May 31, 8:47 am, quill <[email protected]> wrote:
> hi Anton, is there some example code to refer to?
>
> On 5月31日, 下午10时35分, Anton <[email protected]> wrote:
>
> > Usually this is solved by having ray-object intersection code for
> > all of your geometry. If your 3D objects are all polygon meshes then
> > you need ray-polygon intersection code. You then generate a ray from
> > the eye point through the screen point that the user is touching.
> > This ray is then tested against all of your geometry to find the
> > closest hit. That tells you what object was hit as well as where on
> > the object. Of coarse, if your scene has many objects with lots of
> > polygons to test you will want to use some sort of spacial data
> > structure to speed up the hit testing. However, since you only need
> > it to run at "human speeds" you can get away with doing a lot of hit
> > tests before you have to resort to acceleration structures. One
> > simple thing to do is to hit test the objects bounding volumes
> > (spheres are particularly easy). That lets you not test the
> > individual polygons in objects that fail the bounding volume test. If
> > you have scripts for your objects that need to receive touch events
> > you can pass the event along to the object once you've determined
> > which object is hit.
>
> > -Anton
>
> > On May 31, 2:24 am, quill <[email protected]> wrote:
>
> > > HI all,
> > > I am writing a game using OPENGL, there are several 3D objects in my
> > > surfaceview.
> > > My question is:
> > > Should each 3D object implement view in order to get touch events?
> > > Or there is other way to do this?
>
> > > Thank you!
>
>
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