hi all..

I'm just getting into a VRAY procedural implementation and would like to optimize performance without getting into multithreading the procedural (we depend on an infrastructure which is not multithreaded). The procedural is expected to deliver geometry for large crowds. With that in mind, i had a few questions:

1) Can batching similar geometry and materials when calling addGeometry() from within the procedural significantly improve Mantra's performance? i.e. submit all instances of a particular mesh or material together. In OpenGL renderers this minimizes the number of state changes, but i'm not sure if Mantra cares.

2) If i have a bounding box with 1000 instances of a mesh with the same topology, but displaced vertices and different materials, is there a way to optimize the rendering of that geometry from within a procedural? Something like NVidia's demo at http://developer.download.nvidia.com/SDK/10/direct3d/Source/SkinnedInstancing/doc/SkinnedInstancingWhitePaper.pdf [developer.download.nvidia.com] , though i suspect it's a bit harder to do on non-NVidia hardware :>).

3) when render() is called, is it possible to determine the visible, 3D portion of the bounding box which needs to be rendered? This might result in significant savings if bounding box size is increased.

4) given that the procedural is single-threaded, are there recommended practices to balance the rendering so that it is not bound by the procedural's performance? I'm thinking along the lines of:
a) tuning the size of the micropolygon buckets, or other parameters which might increase the amount of time between calls to the procedural render()
b) controlling shader complexity
c) increasing the procedural's bounding box size
d) increasing the number of characters within the bounding box

Hope they're not FAQs..

Thanks!

Cinesite did dust strikes using custom microsolvers for Clash of the Titans (http://www.sidefx.com/index.php?option=com_content&task=view&id=1838&Itemid=68 [sidefx.com]), an approach which requires significantly more expertise. But it's a true volumetric effect which is also capable of handling depression of the ground so perhaps it is worth it for some frames.

http://code.google.com/p/h2k/ [code.google.com] :>).

Thanks Jeff.. i did look at the type properties window before asking but missed the “Export Parameter to Type Properties” menu option .

hi all..

Does anyone know if it is possible to emulate the Mantra ROP “Extra Image Planes” parameter UI in a custom SOP? It doesn't look like it is using the standard widgets contained in the type properties dialog.

thanks!

hey 42.. i like your fractal flame 8) . Shades of Doc Baily!

BTW Nuke can generate motion blur from 3D passes as well.

I'm just curious whether there is a way to specify the allocation size of an attribute. I'm storing attributes into another file format and it would be nice, if possible, to specify half-float storage in a Houdini-compatible way. There is a GB_STORAGE_FPREAL16 in the HDK, but the AttribCreate SOP doesn't seem to allow this level of control.

Just curious whether anyone has integrated stackless python with Houdini.

Thanks tamte.. your suggested fix works for me. Do you know how the anti-aliasing is determined (screen-level? REYEs-level?)? It seems razor-sharp and if i put a variously-coloured grid behind it the curve colours don't appear to change.

hi all..

I'm trying to map a strip of pixels from the edge of a texture map to a NURBs curve. I've given it a try (attached), and the UVs look ok, but the rendered colours don't seem to match any of the edges of the standard UVcolor.png. Does someone know what i'm missing?

thanks!

Just a minor note, but i've added a rotate VOP to the example in case anyone else might want it.

the modulo VOP is rather interesting :>). Thanks! It's one of those things where you're wondering how best to do it.

ah.. i see. Thanks - that will work fine for my purposes. Now i just have to figure out how to access the positions of the first and last points in the primitive to put the vector between them into an attribute. I don't see a way to do this using the Primitive or AttribCreate SOPs.. perhaps i miss something. Is there a way to do this using existing components?

hi all..

I wrote a SOP to rotate a primitive about an axis defined by its first and last points. Since it isn't modifying geometry i used VEX for its portability and speed, but there doesn't seem to be a way to define or use local variables in the parameters. Looked about and, judging by a post at http://forums.odforce.net/index.php?/topic/8200-vex-sop-and-local-variables/, [forums.odforce.net] this feature may not be supported.

Maybe i'm missing something or there is an easier/better way to do this task?

I could use Python or C++, but the operation in question is performed frequently. Is there a convenient way to add parallelism to HDK SOPs running on the CPU?

thanks!

thanks circusmonkey! Regrettably i haven't found a way to search the RFEs so i must ask you these questions .

hi all..

Just wondering if there are any examples of creating motion blur data for use in COPs. I've tried exporting a 32-bit EXR channel using getblurP(), but the Velocity Blur COP wants velocity data and states that it “can't quite do true motion blur”. There seem to be lots of ways to get the data into Reelsmart and other tools in any case.

thanks

Thanks.. there are so many ways to do things in Houdini that i have to resist the temptation to jump in and invent wheels .

hi all..

I would like to increase the number of points in a curve at areas of greatest curvature. I've looked at the Measure SOP, which is very handy, but it seems to be for 3D surfaces. Maybe there is a better solution?

thanks

For anyone following up, Kalle-Samuli Riihikoski has done some work with 3DC and Houdini:
http://www.vimeo.com/15867403 [vimeo.com]

Here is example.. not guaranteed to be the best way, though.