for some reason when i do this tutorial and use the pic() expression the performance is very very slow compared to his system. I have a quad core.
but it takes 10 seconds to compute one frame for just a few particles. in his scene it is considerably faster!

any ideas as to why this expression is performing so slowly?

You would have to attach your working file for us to help.

here tis. the colors also dont seem to render…

Hi,

This issue has been already raised some time last year, and as far as I know you can forget about the way it was done in the tutorial - it simply does not work as expected in 10.x.

I recall somebody on the forum posting an alternate, VOP-based solution, which is blazingly fast - I can't do it now, but later tonight I'll try to locate the hip file and will post it here.

Cheers,
Greg

Here is one way of doing this with a vop sop.

wow. that is fast. thanks.

i've tried to use your method on a sphere of particles and using a spherical uv map node. however in this situation it doesn't seem to pickup up the color properly. why might this be?

change your uv attribute to point instead of vertex(which is not inherited by pops)
you can do it in uvtexture SOP, just specify Apply To parameter to Point Texture

to avoid bad uvs, you can add Facet SOP before uvtexture and check Pre-compute Normals and Unique Points

tamte
change your uv attribute to point instead of vertex(which is not inherited by pops)
you can do it in uvtexture SOP, just specify Apply To parameter to Point Texture

to avoid bad uvs, you can add Facet SOP before uvtexture and check Pre-compute Normals and Unique Points

I have followed this way of using vops and it is still not working for me could someone take a look at my hip file. the image is not showing up ?

Thanks

Lyonz
I have followed this way of using vops and it is still not working for me could someone take a look at my hip file. the image is not showing up ?

Thanks

Your parameter vop reads UV it should be lower case uv.

mawi

Lyonz
I have followed this way of using vops and it is still not working for me could someone take a look at my hip file. the image is not showing up ?

Thanks

Your parameter vop reads UV it should be lower case uv.

Thanks it works fine now. Wondering if i have this method straight ?

1. Grid used to create particles on surface.
2. The texture node used gets inherited to the pop network for visualisation to work.

3. Vop sop used acts as some type of shader ?

4. (Vop sop) Colour map used to load in a texture but why not use some other texture node ?

5. Why does the the vop network need uv parameter instead of a uv constant to work ? as i thought the uv would always be the same and the particle system is revealing the image.

Lyonz

mawi

Lyonz
I have followed this way of using vops and it is still not working for me could someone take a look at my hip file. the image is not showing up ?

Thanks

Your parameter vop reads UV it should be lower case uv.

Thanks it works fine now. Wondering if i have this method straight ?

1. Grid used to create particles on surface.
2. The texture node used gets inherited to the pop network for visualisation to work.

3. Vop sop used acts as some type of shader ?

4. (Vop sop) Colour map used to load in a texture but why not use some other texture node ?

5. Why does the the vop network need uv parameter instead of a uv constant to work ? as i thought the uv would always be the same and the particle system is revealing the image.

Ok I will try.
Maybe someone can fill in with better explanations.

1. Yes

2. Not just for visualisation. The texture node creates uv-coordinates and stores them in a attribute called uv, later used to look up color on image.

3. Its processing points and assigning/transforming attributes and values on them. In this case the color attribute Cd

4. I dont think there is another SOP-node that takes a texture and applies it to a geometry as color without expressions. If you want you can apply the texture at render time through the shader.

5. The parameter node has nothing to do with changing values. It´s just to bring the attribute uv into VOP-context. The constant-VOP is not doing this.

Thanks