first attempt at realistic rendering

1 files changed, 137 insertions, 20 deletions

diff --git a/lib/svg/svg.py b/lib/svg/svg.py
index 852215f2..147fdc84 100644
--- a/lib/svg/svg.py
+++ b/lib/svg/svg.py
@@ -1,9 +1,124 @@
-import simpletransform, simplestyle, inkex
+import math
+import simpletransform, simplestyle, simplepath, inkex
 
-from .units import get_viewbox_transform
-from .tags import SVG_GROUP_TAG, INKSCAPE_LABEL, INKSCAPE_GROUPMODE, SVG_PATH_TAG
+from .units import get_viewbox_transform, PIXELS_PER_MM
+from .tags import SVG_GROUP_TAG, INKSCAPE_LABEL, INKSCAPE_GROUPMODE, SVG_PATH_TAG, SVG_DEFS_TAG
 from ..i18n import _
-from ..utils import cache
+from ..utils import cache, Point
+
+
+# The stitch vector path looks like this:
+#  _______
+# (_______)
+#
+# It's 0.4mm high, which is the approximate thickness of common machine embroidery threads.
+
+# 1.52 pixels = 0.4mm
+stitch_height = 1.52
+
+# This vector path starts at the origin and contains a placeholder (%s) for the stitch length.
+stitch_path = "M0,0c0.386,0,0.417,0.378,0.428,0.759c0.012,0.382,-0.048,0.754,-0.428,0.759h-%sc-0.357,-0.003,-0.399,-0.376,-0.413,-0.759c-0.014,-0.382,0.067,-0.759,0.413,-0.759z"
+
+# This filter makes the above stitch path look like a real stitch with lighting.
+realistic_filter = """
+    <filter
+       style="color-interpolation-filters:sRGB"
+       id="realistic-stitch-filter"
+       x="-0.40000001"
+       width="1.8"
+       y="-0.40000001"
+       height="1.8">
+      <feGaussianBlur
+         stdDeviation="1.5"
+         id="feGaussianBlur1542-6"
+         in="SourceAlpha" />
+      <feComponentTransfer
+         id="feComponentTransfer1544-7"
+         result="result1">
+        <feFuncR
+           id="feFuncR1546-5"
+           type="identity" />
+        <feFuncG
+           id="feFuncG1548-3"
+           type="identity" />
+        <feFuncB
+           id="feFuncB1550-5"
+           type="identity"
+           slope="4.5300000000000002" />
+        <feFuncA
+           id="feFuncA1552-6"
+           type="gamma"
+           slope="0.14999999999999999"
+           intercept="0"
+           amplitude="3.1299999999999999"
+           offset="-0.33000000000000002" />
+      </feComponentTransfer>
+      <feComposite
+         in2="SourceAlpha"
+         id="feComposite1558-2"
+         operator="in" />
+      <feGaussianBlur
+         stdDeviation="0.089999999999999997"
+         id="feGaussianBlur1969" />
+      <feMorphology
+         id="feMorphology1971"
+         operator="dilate"
+         radius="0.10000000000000001" />
+      <feSpecularLighting
+         id="feSpecularLighting1973"
+         result="result2"
+         specularConstant="0.70899999"
+         surfaceScale="33.81000137">
+        <fePointLight
+           id="fePointLight1975"
+           z="10" />
+      </feSpecularLighting>
+      <feGaussianBlur
+         stdDeviation="0.040000000000000001"
+         id="feGaussianBlur1979" />
+      <feComposite
+         in2="SourceGraphic"
+         id="feComposite1977"
+         operator="arithmetic"
+         k2="1"
+         k3="1"
+         result="result3"
+         k1="0"
+         k4="0" />
+      <feComposite
+         in2="SourceAlpha"
+         id="feComposite1981"
+         operator="in" />
+    </filter>
+"""
+
+def realistic_stitch(start, end):
+    """Generate a stitch vector path given a start and end point."""
+
+    end = Point(*end)
+    start = Point(*start)
+
+    stitch_length = (end - start).length()
+    stitch_center = (end + start) / 2.0
+    stitch_direction = (end - start)
+    stitch_angle = math.atan2(stitch_direction.y, stitch_direction.x)
+
+    stitch_length = max(0, stitch_length - 0.2 * PIXELS_PER_MM)
+
+    # create the path by filling in the length in the template
+    path = simplepath.parsePath(stitch_path % stitch_length)
+
+    simplepath.scalePath(path, 1, 0.8)
+
+    # rotate the path to match the stitch
+    rotation_center_x = -stitch_length / 2.0
+    rotation_center_y = stitch_height / 2.0
+    simplepath.rotatePath(path, stitch_angle, cx=rotation_center_x, cy=rotation_center_y)
+
+    # move the path to the location of the stitch
+    simplepath.translatePath(path, stitch_center.x, stitch_center.y)
+
+    return simplepath.formatPath(path)
 
 
 def color_block_to_point_lists(color_block):
@@ -37,22 +152,21 @@ def color_block_to_paths(color_block, svg):
     # We could emit just a single path with one subpath per point list, but
     # emitting multiple paths makes it easier for the user to manipulate them.
     for point_list in color_block_to_point_lists(color_block):
-        color = color_block.color.visible_on_white.to_hex_str()
-        paths.append(inkex.etree.Element(
-            SVG_PATH_TAG,
-            {'style': simplestyle.formatStyle(
-                {'stroke': color,
-                'stroke-width': "0.4",
-                'fill': 'none'}),
-            'd': "M" + " ".join(" ".join(str(coord) for coord in point) for point in point_list),
-            'transform': get_correction_transform(svg),
-            'embroider_manual_stitch': 'true',
-            'embroider_trim_after': 'true',
-            }))
-
-    # no need to trim at the end of a thread color
-    if paths:
-        paths[-1].attrib.pop('embroider_trim_after')
+        color = color_block.color.visible_on_white.darker.to_hex_str()
+        start = point_list[0]
+        for point in point_list[1:]:
+            paths.append(inkex.etree.Element(
+                SVG_PATH_TAG,
+                {'style': simplestyle.formatStyle(
+                    {
+                        'fill': color,
+                        'stroke': 'none',
+                        'filter': 'url(#realistic-stitch-filter)'
+                    }),
+                'd': realistic_stitch(start, point),
+                'transform': get_correction_transform(svg)
+                }))
+            start = point
 
     return paths
 
@@ -78,4 +192,7 @@ def render_stitch_plan(svg, stitch_plan):
                                         INKSCAPE_LABEL: "color block %d" % (i + 1)})
         group.extend(color_block_to_paths(color_block, svg))
 
+    defs = svg.find(SVG_DEFS_TAG)
+    defs.append(inkex.etree.fromstring(realistic_filter))
+
     svg.append(layer)