scaling of flat primitives - Printable Version +- LDraw.org Discussion Forums (https://forums.ldraw.org) +-- Forum: Models and Parts (https://forums.ldraw.org/forum-18.html) +--- Forum: Parts Authoring (https://forums.ldraw.org/forum-19.html) +--- Thread: scaling of flat primitives (/thread-13247.html) scaling of flat primitives - Ingolf Weisheit - 2014-06-21 Hallo, in http://www.ldraw.org/library/primref/ the following is mentioned: "To avoid matrix arithmetic problems in some renderers, the third dimension ({y} in the default orientation) must be given a scaling factor of 1." Is it that strict or is a -1 allowed as well? The reason for the question is that I'm still working on 11767. If I fix the BFC and I mirror or rotate a primitive I get a -1 as scaling factor for y. Is it legal or is it prefered to have a 0 BFC INVERTNEXT statement for many lines of code? regards, Ingolf Re: scaling of flat primitives - Santeri Piippo - 2014-06-21 Both 1 and -1 are legal for flat primitives, yes. Re: scaling of flat primitives - Michael Heidemann - 2014-06-22 The current version of DATHeader finds those "scaled flat subfiles" and will correct this. Re: scaling of flat primitives - Mark Kennedy - 2014-06-23 If you use BFC the sign on the flat dimension will effect which face is displayed so if 1 shows the front -1 will show the back. Re: scaling of flat primitives - Philippe Hurbain - 2014-06-23 Quote:\"To avoid matrix arithmetic problems in some renderers, the third dimension ({y} in the default orientation) must be given a scaling factor of 1.\" Actually I don't think that coefficient in flat direction does matter - except that it shouldn't be 0 (a lot of old LDraw part did have this issue), and of course sign impacts BFC as mentionned by Mark. But anyway we now have a tool that does care for us - thanks, Mike!