Fix for dashed line options not working as expected in some applications

when combined with geometry modifiers.

The problem is that users were not able to choose the time when the
dashed line options are applied.  Instead, the dashed line options were
applied only before geometry modifiers were employed.  Since dashes were
separate strokes, the geometry modifiers were processed dash by dash.
Depending on users' artistic intention, this may or may not lead to
expected stylization results, as reported by octane98 in the
BlenderArtists Freestyle thread on January 3, 2012.
http://blenderartists.org/forum/showthread.php?89986-Freestyle-for-Blender&p=2018592&viewfull=1#post2018592

Now the Strokes tab of the Freestyle Line Style panel has two sets of
dashed line options.  One is in the Splitting section of the Strokes tab
and used for splitting strokes by dashed line patterns.  The other set
is called "Dashed Line" and used to generate dashed lines based on the
strokes after the geometry modifiers are applied.  The two sets of
dashed line options are independent of each other, so that users can
enable one of them as well as both at the same time.

1 files changed, 67 insertions, 22 deletions

diff --git a/release/scripts/freestyle/style_modules/parameter_editor.py b/release/scripts/freestyle/style_modules/parameter_editor.py
index e817771732a..71d55e9a541 100644
--- a/release/scripts/freestyle/style_modules/parameter_editor.py
+++ b/release/scripts/freestyle/style_modules/parameter_editor.py
@@ -762,6 +762,8 @@ class RoundCapShader(StrokeShader):
             r = self.round_cap_thickness((nverts_end - i + 1) * n)
             stroke[-i-1].setAttribute(attr)
             stroke[-i-1].attribute().setThickness(R * r, L * r)
+        # update the curvilinear 2D length of each vertex
+        stroke.UpdateLength()
 
 class SquareCapShader(StrokeShader):
     def shade(self, stroke):
@@ -798,24 +800,26 @@ class SquareCapShader(StrokeShader):
         d = p - q
         stroke[-1].setPoint(p + d / d.length * caplen_beg)
         stroke[-1].setAttribute(attr)
+        # update the curvilinear 2D length of each vertex
+        stroke.UpdateLength()
 
-# dashed line
+# Split by dashed line pattern
 
-class DashedLineStartingUP0D(UnaryPredicate0D):
+class SplitPatternStartingUP0D(UnaryPredicate0D):
     def __init__(self, controller):
         UnaryPredicate0D.__init__(self)
         self._controller = controller
     def __call__(self, inter):
         return self._controller.start()
 
-class DashedLineStoppingUP0D(UnaryPredicate0D):
+class SplitPatternStoppingUP0D(UnaryPredicate0D):
     def __init__(self, controller):
         UnaryPredicate0D.__init__(self)
         self._controller = controller
     def __call__(self, inter):
         return self._controller.stop()
 
-class DashedLineController:
+class SplitPatternController:
     def __init__(self, pattern, sampling):
         self.sampling = float(sampling)
         k = len(pattern) // 2
@@ -845,6 +849,35 @@ class DashedLineController:
             return True
         return False
 
+# Dashed line
+
+class DashedLineShader(StrokeShader):
+    def __init__(self, pattern):
+        StrokeShader.__init__(self)
+        self._pattern = pattern
+    def getName(self):
+        return "DashedLineShader"
+    def shade(self, stroke):
+        index = 0 # pattern index
+        start = 0.0 # 2D curvilinear length
+        visible = True
+        sampling = 1.0
+        it = stroke.strokeVerticesBegin(sampling)
+        while not it.isEnd():
+            pos = it.t()
+            # The extra 'sampling' term is added below, because the
+            # visibility attribute of the i-th vertex refers to the
+            # visibility of the stroke segment between the i-th and
+            # (i+1)-th vertices.
+            if pos - start + sampling > self._pattern[index]:
+                start = pos
+                index += 1
+                if index == len(self._pattern):
+                    index = 0
+                visible = not visible
+            it.getObject().attribute().setVisible(visible)
+            it.increment()
+
 # predicates for chaining
 
 class AngleLargerThanBP1D(BinaryPredicate1D):
@@ -1117,29 +1150,28 @@ def process(layer_name, lineset_name):
         Operators.sequentialSplit(Curvature2DAngleThresholdUP0D(min_angle, max_angle))
     if linestyle.use_split_length:
         Operators.sequentialSplit(Length2DThresholdUP0D(linestyle.split_length), 1.0)
+    if linestyle.use_split_pattern:
+        pattern = []
+        if linestyle.split_dash1 > 0 and linestyle.split_gap1 > 0:
+            pattern.append(linestyle.split_dash1)
+            pattern.append(linestyle.split_gap1)
+        if linestyle.split_dash2 > 0 and linestyle.split_gap2 > 0:
+            pattern.append(linestyle.split_dash2)
+            pattern.append(linestyle.split_gap2)
+        if linestyle.split_dash3 > 0 and linestyle.split_gap3 > 0:
+            pattern.append(linestyle.split_dash3)
+            pattern.append(linestyle.split_gap3)
+        if len(pattern) > 0:
+            sampling = 1.0
+            controller = SplitPatternController(pattern, sampling)
+            Operators.sequentialSplit(SplitPatternStartingUP0D(controller),
+                                      SplitPatternStoppingUP0D(controller),
+                                      sampling)
     # select chains
     if linestyle.use_min_length or linestyle.use_max_length:
         min_length = linestyle.min_length if linestyle.use_min_length else None
         max_length = linestyle.max_length if linestyle.use_max_length else None
         Operators.select(LengthThresholdUP1D(min_length, max_length))
-    # dashed line
-    if linestyle.use_dashed_line:
-        pattern = []
-        if linestyle.dash1 > 0 and linestyle.gap1 > 0:
-            pattern.append(linestyle.dash1)
-            pattern.append(linestyle.gap1)
-        if linestyle.dash2 > 0 and linestyle.gap2 > 0:
-            pattern.append(linestyle.dash2)
-            pattern.append(linestyle.gap2)
-        if linestyle.dash3 > 0 and linestyle.gap3 > 0:
-            pattern.append(linestyle.dash3)
-            pattern.append(linestyle.gap3)
-        if len(pattern) > 0:
-            sampling = 1.0
-            controller = DashedLineController(pattern, sampling)
-            Operators.sequentialSplit(DashedLineStartingUP0D(controller),
-                                      DashedLineStoppingUP0D(controller),
-                                      sampling)
     # prepare a list of stroke shaders
     shaders_list = []
     for m in linestyle.geometry_modifiers:
@@ -1269,5 +1301,18 @@ def process(layer_name, lineset_name):
         shaders_list.append(RoundCapShader())
     elif linestyle.caps == "SQUARE":
         shaders_list.append(SquareCapShader())
+    if linestyle.use_dashed_line:
+        pattern = []
+        if linestyle.dash1 > 0 and linestyle.gap1 > 0:
+            pattern.append(linestyle.dash1)
+            pattern.append(linestyle.gap1)
+        if linestyle.dash2 > 0 and linestyle.gap2 > 0:
+            pattern.append(linestyle.dash2)
+            pattern.append(linestyle.gap2)
+        if linestyle.dash3 > 0 and linestyle.gap3 > 0:
+            pattern.append(linestyle.dash3)
+            pattern.append(linestyle.gap3)
+        if len(pattern) > 0:
+            shaders_list.append(DashedLineShader(pattern))
     # create strokes using the shaders list
     Operators.create(TrueUP1D(), shaders_list)