Posted by BitShifter on April 05, 2000 at 07:04:21:
In reply to: Texture Vertex has "High" flag posted by BitShifter on March 31, 2000 at 11:34:31:
: In the texture list, the vertices have a High flag, which is set if the X/Y coordinate is "high".
: Does "high" here means nearer the top left corner of the whole texture strip?
The Hi-Lo thing is used to make triangle (mostly).
The way to make a triangle is to have the fourth vertex set to zero. If things were left that way, every triangle would have the slanted side on the same side of the basic polygon. It would limit what texture you could put in a triangle (what if that neat little dot thing you wnat in is in the excluded part of the bitmap, heh?).
By rotating, that is, setting vertex No2 in the array as the Hi one, instead of having the default (No1) one can draw a triangle that face some other way.
That way, even though Vertex No4 is set to zero, the actual order in which they are draw is changed.
Of course when one draws the basic figure in the texture strip, one has to un-rotate the coordinates so that the Hi and Lo occupy their default position.
Correct me if I'm wrong.