Initial commit

Version 0.1 for both curveAtFrame and wiggle functions.

README.md

@@ -1,2 +1,46 @@
 # VF-BlenderDriverFunctions
 Functions for use in Blender channel drivers.
+
+Installation and usage:
+- Download the .py file
+- Open up Blender preferences
+- Install the add-on
+- Enable
+- Add a driver to any channel via keyboard shortcut (usually "D"), context menu (right-click), or directly (typing "#" and then the function)
+
+
+## curveAtFrame
+This driver function is intended to mimic Adobe After Effect's "valueAtTime" expression, returning the value of an animated channel from the specified point in time.
+
+After Effects expression reference:
+```javascript
+thisComp.layer("Cube").transform.position.valueAtTime(time-0.167)[0]
+```
+This returns the value of the "Cube" layer's X position from 0.167 seconds in the past, relative to the current time.
+
+Blender driver equivalent:
+```javascript
+curveAtFrame("Cube", 0, frame-5)
+```
+This returns the value of the "Cube" object's first animation curve from 5 frames in the past, relative to the current frame.
+
+Note that Blender's time sampling doesn't allow references to an object's transform property; it has to be an animation curve, and it can only be referenced by index. The first channel that is keyframed will be assigned index 0, the second channel to be animated will be index 1, and so on.
+
+
+## wiggle
+Designed to mimic Adobe After Effect's "wiggle" expression with similar frequency (colloquially known as wiggles per second) and octave settings.
+
+After Effects expression reference:
+```javascript
+seedRandom(4, true);
+wiggle(3, 200, 1)
+```
+This automatically animates a channel using a static seed of 4 with about 3 "wiggles" per second, a potential distance range of -200 to 200 pixels, and 1 octave of noise.
+
+Blender driver equivalent:
+```javascript
+wiggle(3, 0.2, 1, 4)
+```
+This automatically animates a channel and vaguely matches AE's 3 "wiggles" per second, a potential distance range of -200mm to 200mm (if used in a transform channel), with 1 octave of noise, and a random seed of 4 (seeds can be any floating point number, including negative numbers).
+
+Note that unlike After Effects, driver functions in Blender don't automatically receive unique identifiers for each channel they are applied to, so a unique seed value must be provided by the user.

VF_curveAtFrame.py

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+bl_info = {
+ "name": "VF curveAtFrame",
+ "author": "John Einselen - Vectorform LLC",
+ "version": (0, 1),
+ "blender": (2, 80, 0),
+ "location": "Channel driver -> curveAtFrame(\"Cube\", 0, frame-5)",
+ "description": "Adds curveAtFrame(objectName, curveIndex, time) driver function",
+ "warning": "inexperienced developer, use at your own risk",
+ "wiki_url": "",
+ "tracker_url": "",
+ "category": "Rigging"}
+
+# Thanks for the help:
+# https://blenderartists.org/t/read-object-properties-from-a-specific-frame/531238/2
+# https://blender.stackexchange.com/questions/71305/how-to-make-an-addon-with-custom-driver-function
+
+# Example usage:
+# curveAtFrame("Cube", 0, frame-5)
+# returns the "Cube" object's first animation curve value 5 frames in the past
+# note that Blender requires an animation curve to get time-based data, and doesn't reference them by type or name, only index number
+
+import bpy
+from bpy.app.handlers import persistent
+from bpy.app import driver_namespace as dns
+
+def curve_at_time(name, channel, frame):
+ obj = bpy.data.objects[name]
+ fcurve = obj.animation_data.action.fcurves[channel]
+ return fcurve.evaluate(frame)
+
+@persistent
+def load_handler(dummy):
+ dns = bpy.app.driver_namespace
+ dns["curveAtFrame"] = curve_at_time
+
+def register():
+ load_handler(None)
+ bpy.app.handlers.load_post.append(load_handler)
+
+def unregister():
+ bpy.app.handlers.load_post.remove(load_handler)
+
+if __name__ == "__main__":
+ register()

VF_wiggle.py

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+bl_info = {
+ "name": "VF wiggle",
+ "author": "John Einselen - Vectorform LLC",
+ "version": (0, 1),
+ "blender": (2, 80, 0),
+ "location": "Channel driver -> wiggle(2, 0.5, 1, 2.5)",
+ "description": "Adds wiggle(frequency, amplitude, octaves, seed) driver function",
+ "warning": "inexperienced developer, use at your own risk",
+ "wiki_url": "",
+ "tracker_url": "",
+ "category": "Rigging"}
+
+# Thanks for the help:
+# https://blender.stackexchange.com/questions/71305/how-to-make-an-addon-with-custom-driver-function
+
+# Example usage:
+# wiggle(2, 2, 5)
+# this is vaguely comparable to AE's 2 wiggles per second with 2 octaves and a random seed of 5
+
+import bpy
+from bpy.app.handlers import persistent
+from bpy.app import driver_namespace as dns
+from mathutils import noise
+
+def wiggle(freq, amp, oct, seed):
+ time = bpy.context.scene.frame_current / bpy.context.scene.render.fps
+ pos = (time*0.73*freq, time*0.53*freq, seed) # magic numbers to try and mimic the actually-faster-than-per-second wiggle value in AE
+ return noise.fractal(pos, 1.0, 2.0, oct, noise_basis='PERLIN_ORIGINAL') * amp
+
+@persistent
+def load_handler(dummy):
+ dns = bpy.app.driver_namespace
+ dns["wiggle"] = wiggle
+
+def register():
+ load_handler(None)
+ bpy.app.handlers.load_post.append(load_handler)
+
+def unregister():
+ bpy.app.handlers.load_post.remove(load_handler)
+
+if __name__ == "__main__":
+ register()