[Gzz-commits] gzz/Documentation/Manuscripts/Irregu irregu.tex

[Janne V. Kujala]

CVSROOT:        /cvsroot/gzz
Module name:    gzz
Changes by:     Janne V. Kujala <address@hidden>        02/11/13 05:43:14

Modified files:
        Documentation/Manuscripts/Irregu: irregu.tex 

Log message:
        argh, need full 360 degrees for non-vertical cutting planes

CVSWeb URLs:
http://savannah.gnu.org/cgi-bin/viewcvs/gzz/gzz/Documentation/Manuscripts/Irregu/irregu.tex.diff?tr1=1.33&tr2=1.34&r1=text&r2=text

Patches:
Index: gzz/Documentation/Manuscripts/Irregu/irregu.tex
diff -u gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.33 
gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.34
--- gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.33        Wed Nov 13 
02:57:13 2002
+++ gzz/Documentation/Manuscripts/Irregu/irregu.tex     Wed Nov 13 05:43:14 2002
@@ -400,7 +400,7 @@
 However, the tearout shape can rotate, requiring surfaces
 for all tearing directions in the paper. 
 We compute the outer surfaces for a small number of different 
-tearing directions (45 or 60 degress apart) and store them
+tearing directions and store them
 in the components of a texture. 
 The surface corresponding to a a tearing direction between 
 two stored angles is computed 
@@ -410,10 +410,14 @@
 The interpolation works better for non-vertical cutting planes.
 For a vertical cutting plane, the circle may fit in a narrow valley
 only in a certain angle, making large changes in the outer surface
-over small changes of angle. On the other hand, when the cutting
-plane is closer to horizontal, there can be no such gaps,
+over small changes of angle. 
+When the cutting plane is closer to horizontal, there can be no such gaps,
 because the surface is defined as a displacement from a horizontal plane.
-
+On the other hand, it suffices to store only half of the tearing angles
+of a vertical cutting plane, because 180 degree rotation of the plane 
+has no effect.
+A four-component texture can store angles 45 degress apart for a vertical 
+cutting plane and 90 degrees apart for a non-vertical plane.
 
 Non-photorealistic line-width through mip-mapping.
 %Pyramidal parametrics, Lance Williams (mipmap) ref.