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OpenCL Wrangle SOP: Geometry Manipulation on the GPU using OpenCL Aug. 24, 2016, 3:29 p.m.

pusat
I hope you can shed some light on these issues. I'm not a Houdini expert but my current area of research requires the power of the GPU to show promising results.
Thank you for your answers, they helped me get started.

One last thing, I'm having trouble getting a scalar field to work. It may just be my inexperience with houdini, but I created a volume node and added it's name as a parameter to the OpenCL wrangle node, but I get this error on the gasopencl solver.



Can you show/explain a simple setup for this? I tried merging the volume with the points, but houdini didn't like that. The field is passed in as a float array. Do I need to pass in the width/height/depth separately? If so, what would the order of the values be?

In the end, I want the node to run a calculation on each point in a set against both a volume and another set of points. In my HDK implmentation, I had 3 inputs, so I was able to do this, but I can't figure out how I would go about this with only 1 input. Merging the points seems like a bad idea because I'd need to figure out which are which and the mismatched attributes worries me.

Hopefully you can help, I understand if what I'm trying to do is complicated.

How to persist an Attribute in Geometry Detail Aug. 23, 2016, 4:54 p.m.

I have a text file representing a regression tree for some machine learning evaluation I'm doing on the GPU.

I'm using a python node to load the text file data, then calling the following to add a detail to the geometry.
left_attrib = geo.addAttrib(hou.attribType.Global, "left", leftArray)

The problem is that I have to load the text file and call addAttrib every frame for it to persist, costing very precious milliseconds. Am I approaching this wrong? I just need some way to take my data and present it to next node (This OpenCL node: https://www.sidefx.com/forum/topic/44718/). [sidefx.com]

Ideally I'd like to only load the txt file once, maybe if frame is 1 or with some reload button.

I'd really appreciate some help with this, thanks.

OpenCL Wrangle SOP: Geometry Manipulation on the GPU using OpenCL Aug. 16, 2016, 7:01 p.m.

pusat
I added another preset for accurate smoothing of meshes. It's the same code I use in my Smooth SOP which now works in real time even for 100 iterations.
I have some questions.

I noticed that as I scrub back and forth on the timeline and watch the Geometry Spreadsheet window, position values change ever so slightly in both the Smooth and Relax preset examples. From my limited knowledge in this area, my understanding is that this is the nature of GPU programming and the fact that the order of kernels isn't guaranteed. Are there any precautions I'd need to take for this concurrent modification of data values? In this case it is fine given the nature of the problem, but I am just curious for things I might need to look out for as I attempt my own programming.

The point of this otl is for facilitating general purpose opencl in Houdini, correct?

What is the point of the “barrier ( CLK_LOCAL_MEM_FENCE );” in the Smooth code?

There is a “Recompile Kernel” check box, but intuitively I'd assume this should be a button. Is this doing something I'm not understanding?

Is copying memory back and forth between the device and the GPU handled automatically in opencl? I was learning a bit of CUDA and I had to handle that myself.

I hope you can shed some light on these issues. I'm not a Houdini expert but my current area of research requires the power of the GPU to show promising results.