post by Eji @ 10 八月, 2007 06:48

• Real-time radiosity
• Dynamic lighting environments
• Colour bleeding
• Soft shadows
• Character lighting
• Ambient occlusion
• Specular highlights
• Normal mapping
• HDR
• Cross-platform compatibility

Lots of good examples of SPUs doing useful things
- 'Offline' image processing
- Animation
- Physics
- Compression
- Progressive meshing
- Blend shapes
- Extreme vertex/triangle processing
(see: The Naughty Dog guys talk from gdc 2007:
https://ps3.scedev.net/projects/gdc_2007) *：需要帳號
- Clearly very powerful!

Not so hot at replacing fillrate
- Bit difficult to use it as a substitute GPU
- Can't really render part of the scene on SPU and combine results on GPU
Triangle rasterisation setup, streaming…
Hardware filtering, mipmaps, perspective correction…Antialiasing,zbuffering,stencilling…
GPU really benefits from having dedicated hardware for this
Would be god damn complicated
- Also not really workable for post processing
Render scene >dma round through SPUs >process >render through GPU again
Could delay results by a frame?
Still not particularly desirable and large amount of data to move

Most previous work has focused on vertex based operations
- Makes sense given flexibility of SPUs
RSX can efficiently read textures straight from main memory
- Huge advantage for generating anything intended for the GPU on the SPU
- One of the best points of the PS3 architecture
Textures easy to process on SPUs
- Simple to stream in/out in chunks
- However, random accesses need to be made coherent - so not much good if you can't do this
Easy to do inplace modifications
- Possibility of progressively updating a texture
- No need to double buffer if you get sync right

Memory bandwidth is likely to be the bottleneck
- Generating large textures is going to generate problems in a heavily loaded system
- Generating full screen images still going to be unfriendly
- Compression is your friend
- Need to make your memory usage count
Textures are just a storage medium
- Ultimately just a way of getting data into shaders
- Many possibilities!

Originally implemented a GPU version for reference on the PS3
- Runs perfectly fine, but expensive resource

SPU version much faster
- System runs in 5ms on a single SPU (!)
- That's = 1/3r d of an SPU @ 60 fps
- Or 5% of the total SPU potential at 60fps
That' s why we are excited
- Algorithm is scalable so we can crank up the quality
- Still need to explore possibilities unique to the PS3
- SPUs are more flexible than GPUs - haven't really exploited this yet
- Very promising future!