once apon a time far far away....clip points by camera view

[squardis]

Hi,

Once Upon a time far far back in the old houdini, I saw a example of someone clipping all the point that are not in the viewport.

Now I know it is possible with volumes. but I need a node / way that does that on points (for example Instances)

Does anyone know?

THNX

 

[dimovfx]

With Volume SOP you can create Volume based on Camera View. Then you can use Gourp SOP with Bounding Volume to isolate points inside Camera Frustum.

[iamyog]

in an attribWrangle:
 

vector _ndc = toNDC("/obj/cam1", @P);

float _errorx = ch("errorx");
float _errory = ch("errory");
float _errorz = ch("errorz");

if ((_ndc[0] < 0 - _errorx) || (_ndc[0] > 1 + _errorx))   removepoint(geoself(), @ptnum);
if ((_ndc[1] < 0 - _errory) || (_ndc[1] > 1 + _errory))   removepoint(geoself(), @ptnum);
if ((_ndc[2] > 0 + _errorz))   removepoint(geoself(), @ptnum);

update the path to your camera, then set your error margins accordingly

[davpe]

 

[squardis]

I cant try it at the moment rightnow but if you scatter point I think it breaks becouse there is no volume
am I right?

 

[davpe]

you're not. the volume is created out of camera frustrum and used as a mask for grouping points.

[squardis]

38 minutes ago, iamyog said:

in an attribWrangle:
 

vector _ndc = toNDC("/obj/cam1", @P);

float _errorx = ch("errorx");
float _errory = ch("errory");
float _errorz = ch("errorz");

if ((_ndc[0] < 0 - _errorx) || (_ndc[0] > 1 + _errorx))   removepoint(geoself(), @ptnum);
if ((_ndc[1] < 0 - _errory) || (_ndc[1] > 1 + _errory))   removepoint(geoself(), @ptnum);
if ((_ndc[2] > 0 + _errorz))   removepoint(geoself(), @ptnum);

update the path to your camera, then set your error margins accordingly

Is this a quicker approche in multithreading than the rest?
And where to put this? ( wrangles are getting better and better, but still learning)

[squardis]

6 minutes ago, davpe said:

you're not. the volume is created out of camera frustrum and used as a mask for grouping points.

Thanx!!! It works!!! 
straighth from my mobile and teamviewer   and ofcourcse a big thnx to you guys!!!

 

[davpe]

you're welcome. wrangle solution seems to be more elegant though. and will definitely perform faster with lots of geometry.