mantra -u question

[ahassan]

Hi !

sorry for "doublepost" my question (from houdini forum) but i could not find solution for my problem.

I tried to bake into texturemap my whole shaded/subdivided geomery by using a "prepass" mantra node (using mantra -u).

The goal is to get back all the final illumination and and final normal(displace,bump..) data from the object it one map, then reuse this map into the second render pass by a custom shader.

My problem is that the baking function works only when there are no "render as subdiv" option on my object.The other problem is the displacement.

A regular `displace anong normal` node is attached to my geo and in the normal mantra pass it renders well ,but with mantra -u it renders black(like something bound problem)(my surface shader handles both front/backface so i think it's not because of this).

Could anyone give some advise for these problems?

thanks in advance

Ashraf

[Jason]

You could try add a property to your ROP (or object or material) to turn off "True Displacements". It may help with that problem.

[ahassan]

Hi Jason,

Thanks for the reply, it works but just for the correct surface normals and surfaceshading(color) data.For getting the correct shadowed shading it is a difference between the displaced and the "bumped"(true displace off) versions.

We try to implement our custom mentalray shader into mantra which has an SSS buffer.Unfortunately it needs all the correct shadowing info from the current scene,without it it is will be biased from the diffuse shading pass producing compositing artifacts.I attached a sample picture how does it looks right now under mentalray, it shows how "sharp" could be the sss data at the shadow border regions.

back to the true displacement problem here is another pic ,it shows that the shadows came from the base object which is not displaced.

This uv baked data is used in other passes for the sss so the shadow won't be correct in the final sss pass.Is there any option to get it work with true displacement?

other interesting thing is some camera clipping issue in uv baking which i thought is camera independent.

I read some post before that the surface shader should handle both back/front normals. This shader i used has this solution(isFrontFace) for the illumination loop.

Am i missed somethig?(is there any auto clipping optimalization in mantra?, sorry i'm not very familiar with the rendering options in mantra).

thanks again,

Ashraf