Imagination PowerVR SDK Blog

Is this optimization trick still true?


#1

from OPENGL ES GUIDE of IOS,
https://developer.apple.com/library/ios/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/BestPracticesforShaders/BestPracticesforShaders.html#//apple_ref/doc/uid/TP40008793-CH7-SW3
they say:
[blockquote]Note: It may not seem obvious, but any calculation on the texture coordinates counts as a dependent texture read. For example, packing multiple sets of texture coordinates into a single varying parameter and using a swizzle command to extract the coordinates still causes a dependent texture read.[/blockquote]
as far as I know, it’s PowerVR chips only, but is this still true to new PowerVR GPUs ?


#2

Hi,

Dependent texture reads are significantly more efficient on PowerVR Rogue (Series 6) Graphics Cores than SGX (Series 5). However, there are still small performance gains to be had, so applications should (if possible) calculate UV coordinates before fragment shader execution.

Regards,
Shaun