sub: draw the redirected subwindows using the mesh

1 files changed, 63 insertions, 13 deletions

diff --git a/sub/sub.c b/sub/sub.c
index 6a2425c..ece0e07 100644
--- a/sub/sub.c
+++ b/sub/sub.c
@@ -16,6 +16,7 @@ typedef struct
     Pixmap p;
     int width, height;
     XTriangle *mesh;
+    cairo_matrix_t *m;
     int nNormTri;
     int nTotal;
     bool drawing;
@@ -67,6 +68,7 @@ meshWindow (XTriangle *t, int px1, int py1, int px2, int py2,
                           int cx1, int cy1, int cx2, int cy2)
 {
     meshSquare (&t[0], px1, py1, px2, py2, cx1, cy1, cx2, cy2);
+
     /* Top Row */
     meshSquare (&t[4], SHRT_MIN, SHRT_MIN, px1, py1, SHRT_MIN, SHRT_MIN, cx1, cy1); 
     meshSquare (&t[8], px1, SHRT_MIN, px2, py1, cx1, SHRT_MIN, cx2, cy1);
@@ -89,23 +91,61 @@ static SubWindow
     return NULL;
 }
 
-static void
-paintTri (cairo_t *cr, cairo_surface_t *s, XTriangle p, XTriangle c)
+/* http://www.nsa.gov/academia/_files/collected_learning/high_school/algebra/fractal_fern.pdf */
+static cairo_matrix_t
+setupMatrix (int xp1, int yp1, int xp2, int yp2, int xp3, int yp3,
+	     int xc1, int yc1, int xc2, int yc2, int xc3, int yc3)
 {
+    cairo_matrix_t m;
+    cairo_matrix_t inv;
+    double b6, b7, b8, b9, f6, f7, f8, f9;
+    double det;
+
+    b6 = xc1*(yc2 - yc3) + xc2*(yc3-yc1) + xc3*(yc1-yc2);
+    b7 = xp1*(yc2 - yc3) + xp2*(yc3-yc1) + xp3*(yc1-yc2);
+    b8 = xc1*(xp2 - xp3) + xc2*(xp3-xp1) + xc3*(xp1-xp2);
+    b9 = xc1*(yc2*xp3 - yc3*xp2) + xc2*(yc3*xp1-yc1*xp3) + xc3*(yc1*xp2-yc2*xp1);
+    f6 = b6;
+    f7 = yp1*(yc2 - yc3) + yp2*(yc3-yc1) + yp3*(yc1-yc2);
+    f8 = xc1*(yp2 - yp3) + xc2*(yp3-yp1) + xc3*(yp1-yp2);
+    f9 = xc1*(yc2*yp3 - yc3*yp2) + xc2*(yc3*yp1-yc1*yp3) + xc3*(yc1*yp2-yc2*yp1);
+
+    m.xx = b7/b6;
+    m.xy = b8/b6;
+    m.x0 = b9/b6;
+    m.yx = f7/f6;
+    m.yy = f8/f6;
+    m.y0 = f9/f6;
+
+    det = (m.xx*m.yy-m.xy*m.yx);
+    inv.xx = 1/det * m.yy;
+    inv.yy = 1/det * m.xx;
+    inv.xy = -1/det * m.xy;
+    inv.yx = -1/det * m.yx;
+    inv.x0 = -1/det * (m.yy*m.x0 - m.xy*m.y0);
+    inv.y0 = -1/det * (m.xx*m.y0 - m.yx*m.x0);
 
+    return inv;
+}
+
+static void
+paintTri (cairo_t *cr, SubWindow *s, int i)
+{
+    cairo_pattern_t *pattern = cairo_pattern_create_for_surface (s->s);
+    cairo_pattern_set_matrix (pattern, &s->m[i]);
+    cairo_set_source (cr, pattern);
+    cairo_move_to (cr, s->mesh[2*i].p1.x >> 16, s->mesh[2*i].p1.y >> 16);
+    cairo_line_to (cr, s->mesh[2*i].p2.x >> 16, s->mesh[2*i].p2.y >> 16);
+    cairo_line_to (cr, s->mesh[2*i].p3.x >> 16, s->mesh[2*i].p3.y >> 16);
+    cairo_fill (cr);
+    cairo_pattern_destroy (pattern);
 }
 
 static void
 drawSubWindow (cairo_t *cr, SubWindow *s)
 {
-    /* The next two lines are just temporary, until I write proper code to draw
-     * arbitrary triangles in the mesh - which will allow for more exotic
-     * meshes to be used, and really neat effects to be done
-     */
-    cairo_set_source_surface (cr, s->s, s->mesh[0].p1.x>>16, s->mesh[0].p1.y>>16);
-    cairo_paint (cr);
     for (int i = 0; i+1 < s->nNormTri; i+=2)
-        paintTri (cr, s->s, s->mesh[i], s->mesh[i+1]);
+        paintTri (cr, s, i/2);
 }
 
 static void
@@ -195,12 +235,22 @@ main (int argc, char **argv)
     for (int i = 0; i < N_SUB; i++)
     {
 	sub[i].nTotal = 36;
-        sub[i].mesh = malloc (sizeof(XTriangle) * sub[i].nTotal);
         sub[i].nNormTri = 4;
+        sub[i].mesh = malloc (sizeof(XTriangle) * sub[i].nTotal);
+        sub[i].m = malloc (sizeof(cairo_matrix_t) * sub[i].nNormTri / 2);
         meshWindow (&sub[i].mesh[0], CSIZE*i, CSIZE*i, CSIZE*(i+1), CSIZE*(i+1), 0, 0, CSIZE, CSIZE);
         XCompositeSetTriangularCoordinateMesh (d, sub[i].id, sub[i].mesh, sub[i].nNormTri, sub[i].nTotal - sub[i].nNormTri);
         sub[i].p = XCompositeNameWindowPixmap (d, sub[i].id);
 
+	for (int j = 0; j < sub[i].nNormTri; j+=2)
+	{
+	    XTriangle p = sub[i].mesh[j];
+	    XTriangle c = sub[i].mesh[j+1];
+	    sub[i].m[j/2] = setupMatrix (p.p1.x>>16, p.p1.y>>16, p.p2.x>>16, p.p2.y>>16, p.p3.x>>16, p.p3.y>>16,
+					 c.p1.x>>16, c.p1.y>>16, c.p2.x>>16, c.p2.y>>16, c.p3.x>>16, c.p3.y>>16);
+
+	}
+
         sub[i].s = cairo_xlib_surface_create (d, sub[i].id, v, CSIZE, CSIZE);
         sub[i].cr = cairo_create (sub[i].s);
 
@@ -229,7 +279,7 @@ main (int argc, char **argv)
         }
         break;
         case MotionNotify:
-            if ( ev.xany.window == w ) continue;
+            if ( ev.xany.window == w ){fprintf(stderr,"(%d %d) (%d %d)\n",ev.xbutton.x_root, ev.xbutton.y_root, ev.xbutton.x, ev.xbutton.y); continue;}
             SubWindow *s = findSubwindow (ev.xany.window);
             if(s->drawing)
             {
@@ -240,7 +290,7 @@ main (int argc, char **argv)
                 cairo_stroke (s->cr);
                 drawWindow (cr);
 fprintf(stderr,"ev - w:0x%x\t(%d %d)\t(%d %d)\n",(unsigned)ev.xany.window,ev.xbutton.x_root, ev.xbutton.y_root,ev.xbutton.x, ev.xbutton.y);
-int x, y, rx, ry;
+/*int x, y, rx, ry;
 Window child, root;
 unsigned mask;
 XTranslateCoordinates (d, RootWindow(d, 0), s->id, ev.xbutton.x_root, ev.xbutton.y_root, &x, &y, &child);
@@ -248,7 +298,7 @@ XTranslateCoordinates (d, s->id, RootWindow(d, 0), ev.xbutton.x, ev.xbutton.y, &
 fprintf(stderr,"tr - w:0x%x\t(%d %d)\t(%d %d)\n",(unsigned)ev.xany.window,rx,ry,x,y);
 XQueryPointer (d, s->id, &root, &child, &rx, &ry, &x, &y, &mask);
 fprintf(stderr,"qu - w:0x%x\t(%d %d)\t(%d %d)\n\n",(unsigned)ev.xany.window,rx,ry,x,y);
-            }
+*/            }
             s->x = ev.xbutton.x;
             s->y = ev.xbutton.y;
             break;