D3DXMATRIXA16 what "A16" mean?

Graphics and GPU Programming Programming

Started by katsh October 06, 2006 09:16 PM

6 comments, last by katsh 17 years, 6 months ago

140

Author

October 06, 2006 09:16 PM

D3DXMATRIXA16 , -A16 is what? my guess is,, 1. 16bit Alignment 2. cause there is 16 element(_11..._44) which 1? or other meaning?

dave

2,188

October 06, 2006 09:17 PM

jpetrie

13,220

October 06, 2006 09:36 PM

The SDK documentation explains it rather well, and in much more detail. But yes, it's the alignment option.

katsh

140

Author

October 06, 2006 09:47 PM

thx guys.
smoke in my brain was wiped.

Dunge

405

October 06, 2006 11:24 PM

Aligned on 16bit memory

FReY

424

October 07, 2006 12:17 AM

16 *byte* aligned.

do unto others... and then run like hell.

Evil Steve

2,021

October 07, 2006 08:09 AM

Quote:Original post by FReY
16 *byte* aligned.

Yup.

The reason for the alignment is that it can be faster to use the matrix if it's aligned to a certain boundary. SSE2 and 3dNow! both need the matrix aligned. If it's not aligned, I'd guess that D3DX will either copy it to an aligned version, or it'll fallback and use some other method for changing the matrix (E.g. a plain x86 ASM version of a matrix multiply rather than an SSE2 one).

Basically, it's faster to use, but usually takes more memory.