How do I effective sample neighboring pixels and weigh them? I've been doing a simple average the pixels (8 of them) around the point, but since I can't get too accurate, I get ghosting with large blur areas. Is there a better way to blur in a pixel shader? I want to weigh the pixels with the gaussian function, maybe even the separated function (x blur, then y blur) but I want to know how to effectively sample neighboring pixels first.

Ok
what if I passed the dimensions of the texture to the pixel shader, multiply the tex coords (u,v) by the dimension vector(w,h), and then subtract (1,1), and re-divide by the dimenion vector(w,h).

That would give me the difference in texture space between the texel and its neighbors, and multiplying this number by root-2 would give me the diagnols.

this seems like a lot of work though...
darn it

i'll have to do x passes of 8 pixel samples to get a good blur

and screw using gauss's weighing :D

Quote:I've been doing a simple average the pixels (8 of them) around the point, but since I can't get too accurate

how do u mean accurate? U can be accurate down to 1 texel:

1 texel left = Current_coord.x - (1/texture_width)
(y is same)

similarly for 1 texel up:
Current_coord.y - (1/texture_height)


Also if you're trying to average everything in pass thats a bad idea, it's better to use a separable filter (do search on google for separable gaussian kernel). Basically blur horizontally first, then take the blurred texture and blur it vertically. Unfortunately this only works on ps_2_0 cards.. (or ur limited to 4 samples per pass for which u can use the linear sampler instead).