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EntityPick example please

Blitz3D Forums/Blitz3D Beginners Area/EntityPick example please

fox95871(Posted 2008) [#1]
Would someone mind making an example using EntityPick, LinePick, CameraPick, and EntityPickMode? None of the docs have examples for them, though they all refer to each other for reference!? CameraPick has an example, but it doesn't use the other 3 in it, so I don't understand how it relates. Hope someone here can help :)


Beaker(Posted 2008) [#2]
I don't have examples, but EntityPick, LinePick and CameraPick all fundamentally do the same thing. EntityPick does a line pick from the position of the entity (0,0,0) to infinity in front of the entity (0,0,infinity). LinePick is the same but picks from the x,y,z position to an offset position dx,dy,dz relative to the start point.

EntityPickMode chooses whether an entity is picked as an imaginary sphere, imaginary cube, or using the triangles of the mesh.

Hope this helps (a little).


Gabriel(Posted 2008) [#3]
They're all basically raycasting. It casts a ray from any given point in 3D space to any given point in 3D space, and tells you if it hit anything along the way. If it did, it tells you what it hit and where.


Kryzon(Posted 2008) [#4]
Wait wait, I thought entitypick used a sphere, as you can specify the range# of the picking to do. The way you described it's nothing but another linepick in the Z Axis. Is that so?


xtremegamr(Posted 2008) [#5]
This is a simple example. Basically, if the user clicks the sphere with his\her mouse, a message will be displayed.


graphics3d 800,600,0,2

cam=createcamera()
s=createsphere()

;main loop
while not keyhit(1)

setbuffer backbuffer()
cls

if mousehit(1) then
     e=camerapick(cam,mousex(),mousey())
     if e=s then ;if the selected entity is the sphere...
         msg=true ;display a message
     end if
end if

updateworld
renderworld

if msg=true then
     text 0,0,"Ow! That hurt!"
end if

flip
wend



Mortiis(Posted 2008) [#6]
Wait wait, I thought entitypick used a sphere, as you can specify the range# of the picking to do. The way you described it's nothing but another linepick in the Z Axis. Is that so?


It's up to EntityPickMode. If you set the picking mode to sphere for that specific entity, then it shall use sphere.


Stevie G(Posted 2008) [#7]
Wait wait, I thought entitypick used a sphere, as you can specify the range# of the picking to do. The way you described it's nothing but another linepick in the Z Axis. Is that so?


It is just another linepick along the local Z axis of the source entity.

http://www.blitzbasic.com/b3ddocs/command.php?name=EntityPick&ref=3d_a-z


Beaker(Posted 2008) [#8]
My mistake. You are right: EntityPick does have a range. I've never actually used it, cos I use LinePick for most things (more flexible). Your picking can also have a radius which helps prevent lines 'missing' the target with gaps (and math errors) and the like.


Ross C(Posted 2008) [#9]
Note that increasing the raduis also increases the time taken to do the pick.


fox95871(Posted 2009) [#10]
Hmm, this didn't seem to work:



Am I missing something?


Stevie G(Posted 2009) [#11]
Yes, you need to set the entitypickmode of the sphere to 1 or 2.

Stevie


Ross C(Posted 2009) [#12]
e=CameraPick(camera,MouseX(),MouseY())


Won't work. You need to do the pick:

CameraPick(camera,MouseX(),MouseY())
e = PickedEntity()


CameraPick simple executes the linepick. Using Pickedx(), pickedy() etc etc (read the manual) you can get data from the pick. If pickedentity() returns 0, nothing has been picked.


Stevie G(Posted 2009) [#13]
@ Ross, you're wrong. If you run the example above and apply an entitypickmode to the sphere it works just fine. I guess it makes PickedEntity() somewhat redundant.


fox95871(Posted 2009) [#14]
I tried both and neither work. Is there some assumptive thing I'm supposed to already know about? I thought clicking on the sphere was supposed to make the message appear.


Stevie G(Posted 2009) [#15]
As I mentioned in post 11, you need to set the entitypickmode of the sphere. Add this line after the "moveentity sphere ..." line :

EntityPickMode sphere, 1


Works just fine here.

Stevie


fox95871(Posted 2009) [#16]
Oh okay, thanks for explaining that. I was just putting in the code snippets.


fox95871(Posted 2009) [#17]
The only thing I don't understand now is how to make the last parameter of EntityPickMode work in conjunction with EntityVisible, so cube2 will obscure the ghost cube even though it's behind it. I've got cube2 setup as transparent, but I don't know how to do the rest.