what is every element in domainOffset and domainSize stand for?
it is a uint4 number:
kernel.domainOffset(uint(x, y, z, w));
kernel.domainSize(uint(x, y, z, w));
what is the meaning of x,y,z,w in them respectively?
DomainOffset shows the starting point of execution region.
x - starting column, y - starting row, z - starting depth, w - time
Same is for domainSize -
x - domain Width, y - domain Height, z - domain depth, w - time.
4D streams are for future purpose and not supported yet.
starting column start from 0 or 1?
It is 0-based indexing. Please take a look at sample coming with Brook+ SDK under samples\CPP\tutorials