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!