Getting objects to face a camera moving on a path

[ziggx]

Hi there,

I've got a bunch of trees on 2D grids and I want them to face the camera as it moves along the path. I found a thread on Sidefx that showed me how to get the grids to face a transforming camera by using a point sop by plugging in these expressions to the Add Normal: x: point("../../cam1",0,"P",0)-$TX

[old school]

Try the Primitive SOP's Lookat Object parameter. Point it at a camera.

The control you have over the orientation of the primitives is through the UpVector parameter field which will pick up point attributes on your primitives (if they are the same).

The idea is to copy your 2x2 RxC grids to points via the Copy SOP. On the template points feeding in to the right hand input of the Copy SOP, insert a Point SOP and add both N normals (set to 0,0,1 or whatever works) and up set to 0, 1, 0.

In the Copy SOP, enable the "Use Template Point Attributes" and make sure the wild card * is in the To Point Set parameter.

Finally in the Primitive SOPs Up Vector parameters, put $UPX, $UPY and $UPZ to orient your cards upright.

Have a look at the example file to see if this is the behaviour you want.

orient_cards_to_camera_primitive_sop.hip

[ziggx]

Hey Old School,

Absolutely spot on! Thank you very much - I've been bashing my head against the wall for most of the day on this.

Many thanks

Ziggx

[anim]

if you need planes to rotate only in Y axis so the trees always stay on the ground

then you can use something like you have in your first post

orient_card_roty_to_camera.hip

[ziggx]

if you need planes to rotate only in Y axis so the trees always stay on the ground

then you can use something like you have in your first post

Thanks anim - the trick is to use template point attributes in the copy sop - I was missing that.

Best Wishes

Ziggy