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I think ray tracing will be handled well enough by generic GPU hardware simply using APIs like Vulkan. Nvidia probably oversold their dedicated components, and

by shmerl 8y ago

I think ray tracing will be handled well enough by generic GPU hardware simply using APIs like Vulkan. Nvidia probably oversold their dedicated components, and AMD will try to go the more straightforward way to compete. Which is good, if same thing can be achieved with portable cross-GPU approaches. GPU lock-in is bad and only wastes developers' time.

deleted 8y ago
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dragontamer 8y ago
A huge portion of ray-tracing is fulfilled by generic GPU hardware. Its the bits that NVidia RTX accelerates that makes the difference. The coarse bounding-box check, as well as the ray/triangle intersection check, has DEDICATED hardware on NVidia RTX series (2060, 2070, 2080, and 2080 Ti). This means that NVidia's RTX cards can determine if a ray is intersecting a triangle, or a rectangle, with less power and at higher speeds than other GPUs. That's a very important operation in the overall Raytracing problem. Future GPUs will need to implement this hardware-accelerated intersection check if they wish to be as fast (or faster) than RTX cards. Alternatively, maybe there's an algorithm to do it as fast in software, but that seems unlikely to me.
- Jasper_ 8y ago
  Ray-triangle intersection is a very small part of the overall problem. Surface shading is considerably expensive, and raytracing makes it worse as you don't have any coherent materials or texture access like you did in rasterization. NVIDIA's model also makes it difficult to sort rays by material.
  - dragontamer 8y ago
    > Ray-triangle intersection is a very small part of the overall problem. Its a small part, but a very memory-latency part of the problem. GPUs typically are very bad at memory-latency. Dedicated units would be able to traverse the BVH tree far more efficiently than a typical GPU shader design. The BVH Tree is your typical tree, pointer-chasing on a GPU is way slower than on a CPU, especially with something like the BVH tree which is far larger than can fit in a cache. A typical shader would just be stuck waiting for memory, while RTX Cores can likely process a ton of them in parallel. Hard to say for sure: NVidia didn't say how its RTX Cores work at the assembly level. But it isn't hard to imagine dedicated units that are more efficient than a typical design.
- shmerl 8y ago
  Let's wait and see, but I expect for AMD to come up with a good enough generic solution which will render Nvidia's dedicated hardware obsolete.

by shmerl 8y ago

deleted 8y ago

[deleted]

dragontamer 8y ago

A huge portion of ray-tracing is fulfilled by generic GPU hardware. Its the bits that NVidia RTX accelerates that makes the difference. The coarse bounding-box check, as well as the ray/triangle intersection check, has DEDICATED hardware on NVidia RTX series (2060, 2070, 2080, and 2080 Ti). This means that NVidia's RTX cards can determine if a ray is intersecting a triangle, or a rectangle, with less power and at higher speeds than other GPUs. That's a very important operation in the overall Raytracing problem. Future GPUs will need to implement this hardware-accelerated intersection check if they wish to be as fast (or faster) than RTX cards. Alternatively, maybe there's an algorithm to do it as fast in software, but that seems unlikely to me.

Jasper_ 8y ago
Ray-triangle intersection is a very small part of the overall problem. Surface shading is considerably expensive, and raytracing makes it worse as you don't have any coherent materials or texture access like you did in rasterization. NVIDIA's model also makes it difficult to sort rays by material.
- dragontamer 8y ago
  > Ray-triangle intersection is a very small part of the overall problem. Its a small part, but a very memory-latency part of the problem. GPUs typically are very bad at memory-latency. Dedicated units would be able to traverse the BVH tree far more efficiently than a typical GPU shader design. The BVH Tree is your typical tree, pointer-chasing on a GPU is way slower than on a CPU, especially with something like the BVH tree which is far larger than can fit in a cache. A typical shader would just be stuck waiting for memory, while RTX Cores can likely process a ton of them in parallel. Hard to say for sure: NVidia didn't say how its RTX Cores work at the assembly level. But it isn't hard to imagine dedicated units that are more efficient than a typical design.
shmerl 8y ago
Let's wait and see, but I expect for AMD to come up with a good enough generic solution which will render Nvidia's dedicated hardware obsolete.