Actual location of a parented camera

[AntoineSfx]

I have a rotating null, which drives the rotation of a camera

How do I get the actual location of the camera and its direction in world space ? From the camera object, without rebuilding the transformations manually.

Same question for a constrained (follow path / look at camera)

I'm trying to acquire the origin + directions of the camera in order to find the distance to a specific object in he scene.

[dedeks2999]

Did you try Python expression on sparse param like :

hou.pwd().worldTransform().extractTranslates()[0] for Pos X

hou.pwd().worldTransform().extractRotates()[0] for Rot X

?

[AntoineSfx]

7 hours ago, dedeks2999 said:

Did you try Python expression on sparse param like :

hou.pwd().worldTransform().extractTranslates()[0] for Pos X

hou.pwd().worldTransform().extractRotates()[0] for Rot X

?

Thanks

The UI can fill those fields :

If you need this at Obj level:

Right click on the Tab Header for Transform,  then Reference / Scene Data, then:

obj/cam/Transforms/ World

This will fill T, R, S for you with something like: (for example Translate.X)

{

matrix src_xform = optransform("../cam2");
matrix target_xform_inverted = invert(optransform(opinputpath(".", 0)));
matrix final_xform = src_xform * target_xform_inverted;

matrix rest_xform = identity(4);
matrix self_xform = rest_xform * final_xform;

float result = explodematrixpr(
        self_xform, 
        vector3(ch("./px"), ch("./py"), ch("./pz")),
        vector3(ch("./prx"), ch("./pry"), ch("./prz")),
        chs("./xOrd"), chs("./rOrd"), "TX");
return result;

}

 

and there is no room for error...

 

For my use case, I ended up setting this transform, to a line oriented along Z, at SOP  level, at which point I have a everything I need.

I you do this at OBJ level, obviously in SOP you can't Ray SOP against something else, because it is not transformed yet..