PDA

View Full Version : RGBE vs float HDR



supagu
11-06-2005, 03:15 AM
im looking at HDR rendering, now, im wondering if i should use RGBE or float textures.

what are the pro's and cons of each?

heres my list:

RGBE
pros:
-less memory

cons
-more work on shaders decompressing/compressing

FLOAT
pros:
-less work on shaders

cons
-more memory

i'm guessing i will end up using floats as it would make things simpler and provide better quality, plus im guessing it can support an alpha channel also.

sqrt[-1]
11-06-2005, 03:59 AM
Have you also considered the DXT1 RGB + 16 bit greyscale method that Humus recommends?

You could also include alpha in this scheme if necessary..

Humus
11-06-2005, 11:18 AM
Yes, since you'll get filtering all the way back to R300/NV30, plus less storage space and bandwidth needed, I recommend that method over FP textures. Decoding is three ALU instructions. You may want to check the "HDR Texturing" paper that's included in the latest SDK. It lists a whole range of different formats and encodings that you can use, with their pros and cons.