Assign uv vertex attribute

[haggi]

Hi,

I'm creating polygon geometry and I'd like to add a uv vertex attribute.

The creation of the attribute is done with:

GB_AttributeRef uvRef = gdp.addVertexAttrib("uv", 3, GB_ATTRIB_FLOAT, NULL);

It seems that uvs have to be floats to let houdini read them correctly.

But now I have no idea how to assign my values. For normales it works fine with:

prim_poly_ptr->getVertex(vtxId).setValue<UT_Vector3>(normalRef, n);

Unfortunatly there seems to be no float3 type for the uvs. And assigning a vector like;

prim_poly_ptr->getVertex(vtxId).setValue<UT_Vector3>(uvRef, UT_Vector3(1, 2, 0));

crashes my program. Any tips?

[Macha]

I don't know much about the HDK, but would it even make sense to have uv's stored as vectors (do they form a vector space? Maybe they do, dunno)

From the docs:

http://www.sidefx.com/docs/hdk11.0/hdk_geometry_attributes.html#getsetAttributes

and in particular:

ppt->setValue<float>(uv_id, u, 0);

ppt->setValue<float>(uv_id, v, 1);

and

float life[2];

ppt->set<float>(life_id, life, 2);

Edited August 31, 2011 by Macha

[haggi]

Oh, yes. Thanks a lot. Sometimes I'm lost in the documentation.

[haggi]

Still having a problem. It seems that my vertex attribute definition is wrong. I set it with:

GB_AttributeRef uvRef = gdp.addVertexAttrib("uv", 3, GB_ATTRIB_FLOAT, NULL);

This results in this attribute line in my .geo file:

uv 0 float

But it should look like this:

uv 3 float 0 0 0

And of course because its wrong, noting is set or the tool crashes as soon as I try to set a value.

Any ideas what can be wrong with my method to add an vertex attribute?

edit: Okay I found the problem. The size of the attribute as to be given in bytes not in number of elements, so this will work.

GB_AttributeRef uvRef = gdp.addVertexAttrib("uv", sizeof(float) * 3, GB_ATTRIB_FLOAT, NULL);

Edited August 31, 2011 by haggi