How to judge whether a 3D point is visible or not

[lbsswu]

Hi everyone,

Suppose I have opened the Sketchup software, I want to know whether a 3D point is visible or not in current view.
For example, the 3D point may locate on the back of a person, thus we can't see it when the person facing to us.

This should be done by Sketchup ruby code.Could anyone help me?

[sdmitch]

@lbsswu said:

Hi everyone,

Suppose I have opened the Sketchup software, I want to know whether a 3D point is visible or not in current view.
For example, the 3D point may locate on the back of a person, thus we can't see it when the person facing to us.

This should be done by Sketchup ruby code.Could anyone help me?

I placed a construction point, the little black dot just below the horizon, and "Nancy" in the model. I then used the following code to test if the point was visible.

mod = Sketchup.active_model
ent = mod.active_entities
sel = mod.selection
vue = mod.active_view
eye = vue.camera.eye
cp = ent.grep(Sketchup;;ConstructionPoint)[0]
pt = cp.position
vec = pt.vector_to(eye)
hit = mod.raytest([pt,vec])
if hit
 puts "pt is not visible"
else
 puts "pt is visible"
end

---

---

[slbaumgartner]

@sdmitch, is the logic reversed in your test on hit? I think raytest returns nil if the point is not visible.

OK, I'm confused...unfortunately, the Ruby API site is not responding right now (server issues?) so I can't look at the documentation for raytest.

[sdmitch]

if the ray "hits" something then that means that that object must be between the point and the camera. If there are no obstructions then raytest will return nil.

[slbaumgartner]

@sdmitch said:

if the ray "hits" something then that means that that object must be between the point and the camera. If there are no obstructions then raytest will return nil.

Yeah, I figured that out by experimentation since I can't get to the docs. Thanks!

[lbsswu]

@sdmitch said:

@lbsswu said:

Hi everyone,

Suppose I have opened the Sketchup software, I want to know whether a 3D point is visible or not in current view.
For example, the 3D point may locate on the back of a person, thus we can't see it when the person facing to us.

This should be done by Sketchup ruby code.Could anyone help me?

I placed a construction point, the little black dot just below the horizon, and "Nancy" in the model. I then used the following code to test if the point was visible.

mod = Sketchup.active_model
> ent = mod.active_entities
> sel = mod.selection
> vue = mod.active_view
> eye = vue.camera.eye
> cp = ent.grep(Sketchup;;ConstructionPoint)[0]
> pt = cp.position
> vec = pt.vector_to(eye)
> hit = mod.raytest([pt,vec])
> if hit
>  puts "pt is not visible"
> else
>  puts "pt is visible"
> end
> 

Hi, sdmitch. Thank you very much. It works!