Could anybody explain dFdx and dFdy for me?
I have read 3dLabs's glslang spec for these
two functions but undertand nothing
The spec says:
These two functions are commonly used to estimate
the filter width used to anti-alias procedural
textures.We are assuming that the expression is being
evaluated in parallel on a SIMD array so that at any
given point in time the value of the function is known
at the grid points represented by the SIMD array.
Local differencing between SIMD array elements can
therefore be used to derive dFdx, dFdy, etc.
What does this mean?
for genType dFdx (genType p)
What does 'p' stand for? The input for
the function 'F'? And where is function
thanks a lot...