X-Git-Url: http://git.asbjorn.biz/?a=blobdiff_plain;ds=sidebyside;f=lib%2Fgfxpoly%2Fxrow.h;h=ee0be13cb80bc05028f07d53c7fd4d521e9e3659;hb=1586c1b6a15a2c2514ef5f45133ac0369d1680b6;hp=51300a3f27d4758d0c02678a426d1014b1429245;hpb=f5626be739a1e1b61f89d7a389be3c4b5d4d9128;p=swftools.git

diff --git a/lib/gfxpoly/xrow.h b/lib/gfxpoly/xrow.h
index 51300a3..ee0be13 100644
--- a/lib/gfxpoly/xrow.h
+++ b/lib/gfxpoly/xrow.h
@@ -3,6 +3,8 @@
 
 #include <stdint.h>
 
+#include "poly.h"
+
 typedef struct _xrow {
     int32_t*x;
     int num;
@@ -11,7 +13,39 @@ typedef struct _xrow {
 } xrow_t;
 
 xrow_t* xrow_new();
+
+/* so the idea is this:
+   Before processing any events for a given y, store the list+tree of the current active
+   list (that might be useful anyway for adding xrow points to segments).
+   Then, for every starting segment and for every segment that receives a point, add a (x,segment)
+   tuple to a list which we later sort.
+   These segments will at that point have their *old* fill styles set.
+   Then, order that list, and also merge identical x values using left<->right comparisons on
+   the *old* active list, so that for every x coordinate we have the rightmost (old) segment. (For
+   small active lists, it might be faster to just mark the segments (and store the x in them), and
+   then walk the active list from left to right, collecting marked segments)
+   This list now gives us the information about what the fill areas look like above the scanline and to
+   the right of segments which received a point.
+   Now, apply fill style changes and resort the list, this time using the *new* active
+   list for merging identical x values. That gives us the information on what fill areas look like
+   *below* the scanline and to the right of segments which received a point.
+   Every time an "above" fillstyle differs from a "below" fillstyle, we need to draw a horizontal
+   line (from right to left, using the below fillstyle).
+*/
+
+/* Another approach: since we really only need to know the below *or* above fillstyles in order to
+   determine whether a horizontal line is still needed (if its edgestyle doesn't change the windstate,
+   it's not needed), we can also process horizontal lines after the start events: walk the temporary
+   end segment list and the active list interleaved for each horizontal line, insert horizontal fragments
+   whenever they seem to modify the fillstyle (e.g. apply them with dir=UP).
+   This means that "very horizontal" segments ending in a scanline that encounter hot pixels
+   on their way (and thus don't receive "their" endpoint) need to store a horizontal event. Same for
+   general segments that pass/intersect multiple hotpixels in a scanline.
+*/
+
+
 void xrow_add(xrow_t*xrow, int32_t x);
+
 void xrow_sort(xrow_t*xrow);
 void xrow_dump(xrow_t*xrow);
 void xrow_reset(xrow_t*xrow);