4 ms·

I suppose a lot of ideas behind graphics on Larrabee end up in OpenSWR project. So anyone interested in scientific visualization might check it.

by SXX 10y ago

rubber_duck 10y ago
I think Larrabee was interesting because it had the potential to go the other way - it could emulate existing rasterization APIs decently but would allow for new realtime rendering approaches - like raytracing in to some sparse voxel tree structure for non-animated geometry - maybe do hybrid rendering where you would do deferred shading/rasterization for dynamic scene and then ray trace in to the tree for global illumination with static scene and similar stuff. I'm sure emulating OpenGL on the CPU has it's uses outside of being a reference for drivers and such - but it's not really that exciting, GPUs are already excellent at doing that kind of rendering.
- SXX 10y ago
  Actually it's was not only possible to use it for ray tracing, but Intel had it working back in 2008. They also sponsored Uber Entertainment implement it into their game and that was ready before Intel cancelled it: http://www.polygon.com/features/2013/3/19/4094472/uber-hail-mary-monday-night-combat http://www.polygon.com/features/2013/3/19/4094472/uber-hail-...
- elihu 10y ago
  I also wish that had taken off; 3d-graphics via a software ray tracing engine would in a sense be a return to the way things worked in the 90's before hardware rendering, where every game had its own custom engine and developers were always trying crazy new things. In some sense, GPU hardware has gotten flexible enough that we're sort of back in that world again, but writing GPU code isn't quite the same as writing a renderer from scratch. When it comes to ray-tracing in particular, as far as I know there really doesn't exist (except perhaps as research prototypes) any hardware platform that's great at ray tracing. CPUs are okay but they need more parallelism. GPUs are okay but (as far as I understand it) they aren't good with lots of branches and erratic memory accesses. It seems like KNC/KNL ought to be ideal for this kind of thing (and in fact, it appears a fair bit of effort has gone into optimizing Embree for Xeon Phi).
  - pjmlp 10y ago
    You can still do that kind of stuff, but on the GPU with geometry/compute shaders. Now with Metal, DX12 and Vulkan GPU languages, maybe that is ever more approachable, specially in cards like Pascal.
thechao 10y ago
I joined up in 2009 (really too late), and somehow ended up with the "non polygon" rasterization path (Mike Abrash split rasterization: he had the polygon path). After the second time LRB was canceled, my team was shuttled off elsewhere. I had a number of long conversations with D about soft texturing; I didn't understand Tom Forsyth's arguments about why soft texturing wouldn't work. (My back-of-the-envelope numbers were encouraging.) So, in winter of 2011 (12?) I decided to write my own soft texturing unit. What I found was that soft texturing is completely do-able---just not in any sort of reasonable power budget. At the same time a friend, S, decided he wanted to implement a rasterizer (I'd gotten my fill). Between the two of us, we had a rockin' still-frame bilinearly sampled Stanford bunny. A third friend, W, decided to implement a threading model. Threading models for very-high count processors are enormously difficult. I ended up writing much of an OpenGL driver, a shader compiler (through LLVM), and part of a pipeline JIT, i.e., a vertex loader, fixed-function-to-programmable compiler, etc. That project was called SWR; the sanitized projection is OpenSWR. (Looking at the current sources, I'd say that I probably no longer have any code in there.)
- jeffbush 10y ago
  "decided he wanted to implement a rasterizer (I'd gotten my fill)" I see what you did there. :)

I suppose a lot of ideas behind graphics on Larrabee end up in OpenSWR project. So anyone interested in scientific visualization might check it.

by SXX 10y ago

I suppose a lot of ideas behind graphics on Larrabee end up in OpenSWR project. So anyone interested in scientific visualization might check it.

rubber_duck 10y ago

I think Larrabee was interesting because it had the potential to go the other way - it could emulate existing rasterization APIs decently but would allow for new realtime rendering approaches - like raytracing in to some sparse voxel tree structure for non-animated geometry - maybe do hybrid rendering where you would do deferred shading/rasterization for dynamic scene and then ray trace in to the tree for global illumination with static scene and similar stuff. I'm sure emulating OpenGL on the CPU has it's uses outside of being a reference for drivers and such - but it's not really that exciting, GPUs are already excellent at doing that kind of rendering.

SXX 10y ago
Actually it's was not only possible to use it for ray tracing, but Intel had it working back in 2008. They also sponsored Uber Entertainment implement it into their game and that was ready before Intel cancelled it: http://www.polygon.com/features/2013/3/19/4094472/uber-hail-mary-monday-night-combat http://www.polygon.com/features/2013/3/19/4094472/uber-hail-...
elihu 10y ago
I also wish that had taken off; 3d-graphics via a software ray tracing engine would in a sense be a return to the way things worked in the 90's before hardware rendering, where every game had its own custom engine and developers were always trying crazy new things. In some sense, GPU hardware has gotten flexible enough that we're sort of back in that world again, but writing GPU code isn't quite the same as writing a renderer from scratch. When it comes to ray-tracing in particular, as far as I know there really doesn't exist (except perhaps as research prototypes) any hardware platform that's great at ray tracing. CPUs are okay but they need more parallelism. GPUs are okay but (as far as I understand it) they aren't good with lots of branches and erratic memory accesses. It seems like KNC/KNL ought to be ideal for this kind of thing (and in fact, it appears a fair bit of effort has gone into optimizing Embree for Xeon Phi).
- pjmlp 10y ago
  You can still do that kind of stuff, but on the GPU with geometry/compute shaders. Now with Metal, DX12 and Vulkan GPU languages, maybe that is ever more approachable, specially in cards like Pascal.

thechao 10y ago

I joined up in 2009 (really too late), and somehow ended up with the "non polygon" rasterization path (Mike Abrash split rasterization: he had the polygon path). After the second time LRB was canceled, my team was shuttled off elsewhere. I had a number of long conversations with D about soft texturing; I didn't understand Tom Forsyth's arguments about why soft texturing wouldn't work. (My back-of-the-envelope numbers were encouraging.) So, in winter of 2011 (12?) I decided to write my own soft texturing unit. What I found was that soft texturing is completely do-able---just not in any sort of reasonable power budget. At the same time a friend, S, decided he wanted to implement a rasterizer (I'd gotten my fill). Between the two of us, we had a rockin' still-frame bilinearly sampled Stanford bunny. A third friend, W, decided to implement a threading model. Threading models for very-high count processors are enormously difficult. I ended up writing much of an OpenGL driver, a shader compiler (through LLVM), and part of a pipeline JIT, i.e., a vertex loader, fixed-function-to-programmable compiler, etc. That project was called SWR; the sanitized projection is OpenSWR. (Looking at the current sources, I'd say that I probably no longer have any code in there.)

jeffbush 10y ago
"decided he wanted to implement a rasterizer (I'd gotten my fill)" I see what you did there. :)