Points From Image (only non-alpha)

[Atom]

Hi All,

 

I was just wondering how to get a grid of points from an image? I only want a point where the alpha is on-zero.

 

Is this a COPs to OBJ function?

[eetu]

Create a grid of points, project uvs on it, read rgba values to the points in a vopsop using a texture vop, delete the ones with a==0.

 

Check e.g. http://forums.odforce.net/topic/20716-unofficial-challenge-boxified-images/

[Atom]

Thanks for the starting recipe. I am kind of stuck at adding the VOPSOP. Why doesn't this show up in my list? I tried the object context and inside the object but VOPSOP does not seem to exist anymore in R14?

 

Also, the texture node outputs a clr. How do I convert that to just get the 4th value, alpha, to do the compare?

Edited March 26, 2015 by Atom

[Robert]

Vopsops don't exist anymore. The attribvop has replaced it. I guess many people still make a habit of saying vopsop when they mean the attribvop. (They are afraid to let go of their beloved vopsop!)

In the texture VOP you have to set the signature to RGBA values and then you can use a vector4 to float and take the 4th output, which is your alpha.

Edited March 26, 2015 by Robert

[Atom]

Thanks for the information. I have come a little farther. 

 

There is no Delete in VOP and there is no Group either.

 

How do I remove the unwanted points from the result? (before I map the final points back into P)

Edited March 26, 2015 by Atom

[Robert]

In the attribvop there is the add attribute vop which has the "group" attribute class. Deleting the points is done with the removepoint VOP or outside the attribvop with a blast or delete node.

The removepoint vop only needs a point number so you could skip the adding to group part probably.