From 569abc900f42d8e7b70520e2c9ef8a5547878266 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 16 Jun 2019 11:52:27 +0300
Subject: [PATCH] Add looping detection to animation exporter

Since Blender's actions do not have a looping property, detect looping by
comparing the first and last keyframes of each curve.
---
 blender/io_mspgl/__init__.py         |  2 ++
 blender/io_mspgl/animation.py        | 23 ++++++++++++++++++++++-
 blender/io_mspgl/export_animation.py |  5 ++++-
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/blender/io_mspgl/__init__.py b/blender/io_mspgl/__init__.py
index f0cb6579..3ce60c4c 100644
--- a/blender/io_mspgl/__init__.py
+++ b/blender/io_mspgl/__init__.py
@@ -98,6 +98,7 @@ class ExportMspGLAnimation(bpy.types.Operator, ExportMspGLBase):
 
 	export_all = bpy.props.BoolProperty(name="Export all animations", description="Export all animations present on the selected objects' NLA tracks")
 	collection = bpy.props.BoolProperty(name="As a collection", description="Export the animations as a single collection file", default=True)
+	looping_threshold = bpy.props.FloatProperty(name="Looping threshold", description="Tolerance for curve beginning and end values for looping", min=0.0, soft_max=1.0, precision=4, default=0.001)
 
 	def check(self, context):
 		result = False
@@ -122,6 +123,7 @@ class ExportMspGLAnimation(bpy.types.Operator, ExportMspGLBase):
 		col.prop(self, "export_all")
 		if self.export_all:
 			col.prop(self, "collection")
+		col.prop(self, "looping_threshold")
 
 class ExportMspGLScene(bpy.types.Operator, ExportMspGLBase):
 	bl_idname = "export_scene.mspgl_scene"
diff --git a/blender/io_mspgl/animation.py b/blender/io_mspgl/animation.py
index ffce11f5..59f34b4d 100644
--- a/blender/io_mspgl/animation.py
+++ b/blender/io_mspgl/animation.py
@@ -1,3 +1,4 @@
+import math
 import mathutils
 
 class Curve:
@@ -34,6 +35,7 @@ class Animation:
 		self._action = action
 		self.curves = [Curve(c) for c in action.fcurves]
 		self.fps = 1
+		self.looping = False
 
 		for c in self.curves:
 			for i in range(0, len(c.knots)-1, 3):
@@ -77,6 +79,24 @@ class Animation:
 	def __getattr__(self, attr):
 		return getattr(self._curve, attr)
 
+	def check_looping(self, threshold):
+		self.looping = True
+		for c in self.curves:
+			first_y = c.knots[0][1]
+			last_y = c.knots[-1][1]
+			d = abs(last_y-first_y)
+
+			if c.data_path=="rotation_euler":
+				while d>math.pi/2:
+					d -= math.pi
+				while d<-math.pi/2:
+					d += math.pi
+
+			print("Difference for {} {} is {}".format(c.data_path, c.array_index, d))
+			if d>threshold:
+				self.looping = False
+				break
+
 	def change_fps(self, fps):
 		scale = self.fps/fps
 		self.fps = fps
@@ -89,8 +109,9 @@ class Animation:
 			k.time *= scale
 
 
-def create_animation_from_action(context, action):
+def create_animation_from_action(context, action, *, looping_threshold=0.001):
 	anim = Animation(action)
 	render = context.scene.render
+	anim.check_looping(looping_threshold)
 	anim.change_fps(render.fps/render.fps_base)
 	return anim
diff --git a/blender/io_mspgl/export_animation.py b/blender/io_mspgl/export_animation.py
index e2c7733d..0d72edb4 100644
--- a/blender/io_mspgl/export_animation.py
+++ b/blender/io_mspgl/export_animation.py
@@ -5,6 +5,7 @@ class AnimationExporter:
 	def __init__(self):
 		self.export_all = False
 		self.collection = True
+		self.looping_threshold = 0.001
 
 	def export_to_file(self, context, out_fn):
 		if self.export_all:
@@ -55,7 +56,7 @@ class AnimationExporter:
 
 	def export_animation(self, context, action):
 		from .animation import create_animation_from_action
-		anim = create_animation_from_action(context, action)
+		anim = create_animation_from_action(context, action, looping_threshold=self.looping_threshold)
 
 		from .datafile import Resource, Statement
 		resource = Resource(action.name+".anim")
@@ -100,5 +101,7 @@ class AnimationExporter:
 
 			resource.statements.append(st)
 
+		resource.statements.append(Statement("looping", anim.looping))
+
 		return resource
 
-- 
2.43.0