vulkan: Make fill node handle multiple contours

We still only handle standard contours, but now we can do multiple.

gsk/vulkan/gskvulkanfillop.c

@@ -65,16 +65,31 @@ gsk_vulkan_fill_op_reserve_descriptor_sets (GskVulkanOp     *op,
 {
   GskVulkanFillOp *self = (GskVulkanFillOp *) op;
   const GskContour *contour;
+  gsize size, i, n;
   guchar *mem;
 
-  //g_warn_if_fail (gsk_path_get_n_contours (self->path) == 1);
-  contour = gsk_path_get_contour (self->path, 0);
+  size = sizeof (guint32);
+  n = gsk_path_get_n_contours (self->path);
+  for (i = 0; i < n; i++)
+    {
+      contour = gsk_path_get_contour (self->path, i);
+      size += gsk_contour_get_shader_size (contour);
+    }
 
   mem = gsk_vulkan_render_get_buffer_memory (render,
-                                             gsk_contour_get_shader_size (contour),
+                                             size,
                                              G_ALIGNOF (float),
                                              &self->buffer_offset);
-  gsk_contour_to_shader (contour, mem);
+
+  *(guint32*) mem = n;
+  mem += sizeof (guint32);
+
+  for (i = 0; i < n; i++)
+    {
+      contour = gsk_path_get_contour (self->path, i);
+      gsk_contour_to_shader (contour, mem);
+      mem += gsk_contour_get_shader_size (contour);
+    }
 }
 
 static const GskVulkanShaderOpClass GSK_VULKAN_FILL_OP_CLASS = {

gsk/vulkan/resources/fill.frag

@@ -216,15 +216,16 @@ cubic_distance_squared (vec2 uv,
 }
 
 float
-path_distance (vec2 p)
+standard_contour_distance (vec2      p,
+                           inout int path_idx,
+                           inout int w)
 {
-  int n_points = get_int (in_points_id);
-  int ops_idx = in_points_id + 1;
+  int n_points = get_int (path_idx);
+  int ops_idx = path_idx + 1;
   int pts_idx = ops_idx + n_points;
 
   vec2 start = get_point (pts_idx);
   float d = dot (p - start, p - start);
-  int w = 0;
   int op = GSK_PATH_MOVE;
   
   for (int i = 1; i < n_points; i++)
@@ -273,6 +274,26 @@ path_distance (vec2 p)
       d = min (d, line_distance_squared (p, start, end, w));
     }
 
+  path_idx = pts_idx;
+
+  return d;
+}
+
+float
+path_distance (vec2 p)
+{
+  int path_idx = in_points_id;
+
+  int n = get_int (path_idx);
+  path_idx++;
+  int w = 0;
+  float d = 1e38;
+  
+  while (n-- > 0)
+    {
+       d = min (d, standard_contour_distance (p, path_idx, w));
+    }
+
   if (in_fill_rule == GSK_FILL_RULE_WINDING)
     {
       if (w == 0)