OpenEuphoria

Re: Repeat efficiency

• Posted by Pete Lomax <petelomax at blueyonder.co.uk> Feb 18, 2003
• 480 views

On Tue, 18 Feb 2003 12:30:21 -0800, xerox_irs at lvcm.com wrote:

>"zbuffer=3Drepeat(repeat(0,1024),768)+0.0" --takes a minute but makes

=46irst, take a good, long, hard look at not using fractions. If there
is any way to do this stuff in integers only (eg instead of working
things out in inches with an accuracy of 1/1000th of an inch, just
work everything out in 1/1000th's of inches), then everything will be
fifty times faster as well.

Secondly, especially for something of obviously fixed size like this,
seriously consider allocating a block of memory and knocking up a few
simple routines to peek and poke it. Not strictly euphoria, but once
"black-boxed" you won't care. eg (warning completely untested!):

zbuffer=3Dallocate(1024*768*4)

type x_coord(integer x)
	if x<1 or x>1024 then return 0 end if
	return 1
end type
type y_coord(integer y)
	if y<1 or y>768 then return 0 end if
	return 1
end procedure

procedure setz(x_coord x, y_coord y, integer value)
	poke4(zbuffer+(x-1)*1024+y-1,value)
end procedure

function getz(x_coord x, y_coord y)
	return peek4s(zbuffer+(x-1)*1024+y-1)
end function

You can quickly validate this sort of code by checking that
setz/getz(1,1) stores/gets first four bytes of zbuffer and that
setz/getz(1024,768) the last 4 (ie 1024*768*4-4)

(declare/pass x and y as normal integers, the types above are for
local safety checks only and can be turned off (for speed) by
specifying without type_check once it all works).

HTH

Pete