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

[Tuomas J. Lukka]

CVSROOT:        /cvsroot/gzz
Module name:    gzz
Changes by:     Tuomas J. Lukka <address@hidden>        02/11/30 05:26:06

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

Log message:
        HW

CVSWeb URLs:
http://savannah.gnu.org/cgi-bin/viewcvs/gzz/gzz/Documentation/Manuscripts/Irregu/irregu.tex.diff?tr1=1.107&tr2=1.108&r1=text&r2=text

Patches:
Index: gzz/Documentation/Manuscripts/Irregu/irregu.tex
diff -u gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.107 
gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.108
--- gzz/Documentation/Manuscripts/Irregu/irregu.tex:1.107       Sat Nov 30 
05:09:19 2002
+++ gzz/Documentation/Manuscripts/Irregu/irregu.tex     Sat Nov 30 05:26:06 2002
@@ -410,6 +410,7 @@
 defined region to be viewed should always only move edges outwards 
 or whether they may move back inwards at some point (``ebbing'').
 
+\label{secoptions}
 
 \subsection{Algorithm ``How?''} 
 
@@ -583,6 +584,24 @@
 The image of the undistorted shape can be stored in a texture and accessed
 with texture coordinates offset by (read from) another texture.
 This is called an offset (dependent) texture access.
+
+On hardware without such capabilities, such as the NV10, we can
+obtain a similar effect by constraining the offset
+in the direction of the normal. This can be done by rendering
+into a texture a function which is 1 inside the undistorted shape and
+falls off linearly with distance. The hardware is capable of adding
+the value of such a texture and a noise texture and using that (through
+alpha test) as a condition for drawing the fragment.
+
+We stress that this implementation is not necessarily any worse than
+the offset texture implementation: 
+all its effects are within the options described in Section~\ref{secoptions}.
+
+Naturally, the undistorted shape can also be drawn polygonally, using
+the smooth shading interpolation in OpenGL to obtain the linearly
+falling value
+
+
 
 The shape is given by Eq.~(\ref{eq:inside}), which under the 
 assumptions can be written as a point $(x,y)$ being inside the tearout,