Drivers: "Scripted Expression" drivers (i.e. PyDrivers) work again

Now it is possible to write a Python Expression using the variable names for driver targets (see mockup from initial commit) to substitute the appropriate values into the expression.

In the __global__ namespace for PyDriver evaluation, the following modules are available:
* __builtins__ - i.e. the builtin Python functions
* bpy - new Python API
* math or m - math module

For example:
Consider a driver with three targets, named: A, B, C
Now, you could write an expression like:
   C if A < 5 else B
or even:
   2*C if A < 5 or A > 20 else m.PI*B

Of course, you don't have to have three targets, the above was just an example.

TODO:
* Bring back way to load pydrivers.py
* Blender.Noise equivalent would be nice to have

P.S.  I hope I haven't made any terrible Python API coding errors here (i.e. mem leaks, etc.)

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_fcurve.h b/source/blender/blenkernel/BKE_fcurve.h
index f973f86972d..3dd083476ce 100644
--- a/source/blender/blenkernel/BKE_fcurve.h
+++ b/source/blender/blenkernel/BKE_fcurve.h
@@ -33,6 +33,8 @@ struct ChannelDriver *fcurve_copy_driver(struct ChannelDriver *driver);
 void driver_free_target(struct ChannelDriver *driver, struct DriverTarget *dtar);
 struct DriverTarget *driver_add_new_target(struct ChannelDriver *driver);
 
+float driver_get_target_value(struct ChannelDriver *driver, struct DriverTarget *dtar);
+
 /* ************** F-Curve Modifiers *************** */
 
 /* F-Curve Modifier Type-Info (fmi):