Analogue of Attribute "cull" "backfacing" [0],

[atap3d]

Hi.

I want to ask a question about baking in mantra. I will describe my actions because I am not assured of their correctness. Shader which I use for baking looks so.

Shader which I use for reading baking data looks so.

If I render scene for baking and then I render scene for reading baking data, everything will look normally.

But if I change camera orientation and render this with reading shader, there will appear black areas.

It is correct. Because on back side of surface are no points.

In renderman I will easy add missing points by addition of three attributes in rib:

Attribute "cull" "backfacing" [0]
Attribute "cull" "hidden" [0]
Attribute "dice" "rasteroriented" [0]

Whether there is a similar option in mantra?

I have one more small question. How can I bake more than 2 attribute in point cloud? In pcwrite node there are only two attributes(channels) for bake.

Edited June 1, 2009 by atap3d

[brianburke]

Hi atap3d. The parameter you'll want to add to your rop is Enable Hiding. You'll probably want to add Scanline Measuring, ZImportance, and Measure scale as well to control how the micropolygon grids and the resultant point clouds are generated.

[atap3d]

Thank you. All points have appeared.

But if normal of point isn't turned to the camera, shader on this point doesn't execute.

How to make, that shader has executed on all points?

Edited June 2, 2009 by atap3d

[Jason]

Thank you. All points have appeared.

But if normal of point isn't turned to the camera, shader on this point doesn't execute.

How to make, that shader has executed on all points?

I think they are - but you might running into a Bias issue where the ray origins are biased toward camera and then intersecting the surface immediately. Try adding a "Bias Along Normal" (vm_biasnormal) RenderingParameter and it may help?

I do believe Mantra does shade each and every point it generates.

[atap3d]

Try adding a "Bias Along Normal" (vm_biasnormal) RenderingParameter and it may help?

It hasn't helped.

[brianburke]

Yo atap3d the current artifact isn't really an artifact at all - the shader is running as expected on all the micropolygons. Somewhere in your shader however, there is a faceforward routine that is flipping the normals towards the camera and therefore causing the faces to be shaded as though they were facing the interior of your object. You'll want to get rid of this by unchecking any "ensure faces point forward" parameters.

Edited June 2, 2009 by brianburke

[atap3d]

Thank you, brianburke.

How can I bake more than 2 attribute in point cloud? In pcwrite node there are only two attributes(channels) for bake.

[Jason]

The underlying VEX function can do it: http://www.sidefx.com/docs/houdini10.0/vex/functions/pcwrite

Perhaps look into using the Inline Code VOP and add the line yourself?

You'll find there are quite a few things that you can do in VEX that haven't been properly exposed in VOPs. It's always useful taking a look at the VEX functions inside VOPs every now and then.

Thank you, brianburke.

How can I bake more than 2 attribute in point cloud? In pcwrite node there are only two attributes(channels) for bake.