Category: hou-rendering

Archived post by mattiasmalmer

how do i get the cameras uv space in a materialx shader? i want to do projective texturing in the shader.

This works half-assedly but only on CPUkarma. I load the hit position in worldspace. transform it to cameraspace (using space:camera in the transformpoint) then divide that with hit distance to get a projection. (using ray:hitPz in the mtlxdot) but the camera:space thing does not work in XPU.
I thought this would be the easiest thing ever. anyone having any better tricks?

generating precooked uv data on the geo from the camera is not as good as one tends to get projection errors over larger polygons and such.

ok after the longest time mucking about I found how it is actually done:
You use the coordsys node in LOP:s to define the coordinate system and reference the camera. Then use that coordsys in a mtlxposition and use myCoordinateSysName:ndc to get it in the camera projection space. Neat because then you can use any camera as a projector and so forth.

aw frekk. does not work in xpu.

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Archived post by petersanitra

@squidbean yes and yes, and use .tx, works great for me. You can also use {“KARMA_XPU_OPTIX_SPARSE_TEXTURES” : “1”} to force it to sparse

re mipmapping, it picks correct mipmap level from tx. You can check with this map for example, if you don`t have one around already… dgruwier.gumroad.com/l/LJehG

It`s fun map to use, for example checking displacement, comparing engines etc, fun fun 🙂

Archived post by Peter Sanitra

Re, the difference in volume look on Karma vs Karma XPU. XPU renders at 0.25 step rate by default, and there is no control for it on the ROP, unlike regular Karma CPU. So if you have Regular Karma, have switched volume step rate to 1 on ROP, then your XPU volumes gonna looks “shitty”, compare to that. Way to get nice crisps volumes on XPU is to drop Render geometry settings node and set step rate manually to 1. I`ve seen lot of post about how XPU volumes are ugly, compare to “their engine”, how they lack detail. Yep, they do , when you render at 1/4 res…

Archived post by lewis.taylor

no other engine can do it, so points for that

@tokyomegaplex I’ve been doing this a lot lately

it is a principled shader with no base color, high spec, and low opacity

and a volume rasterizer

you get spec hits, and the white volume look

you’d be able to pump up the spec in comp, this just uses the whitewater particles as is

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Archived post by Maria Mishurenko

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