Sending Color to Specific Location

[SMcNeill]

That's in the spirit of the holiday season!

I was going to change it so it drew a candy cane of text and changed from white to red and green.

I was going to propose "POINT()" but that's unreliable. This program should be studied carefully by beginners before they have anything to do with the "_MEM" functions.

Here's the main thing people need to learn to do with _MEM:

Code: (Select All)

    For y = y1 * _Width * 4 To y2 * _Width * 4 Step _Width
        For x = x1 * 4 To x2 * 4 Step 4

Take the math OUT of the processing loop!!  Most of the time, you see people with something such as:

FOR y = y1 TO y2
    FOR x = x1 TO x2
        IF _MEMGET(m, m.offset + y * 4 * _WIDTH + x * 4, _UNSIGNED LONG) = OldColor THEN _MEMPUT m, m.offst + 4 * _WIDTH + x * 4, NewColor

...

And that's a LOT of math to process inside that loop, which ends up making the mem routines get to the point where they're barely better than POINT and PSET with a plain x/y value. 

If you notice, my whole math formula is a simple: o = m.OFFSET + y + x

That's a LOT less calculations than my previous example up there -- and it's going to be done over and over and over inside that loop!