Maybe something like this might help for the first part of the problem?
import maya.cmds as cmdsimport maya.OpenMaya as om
# This point would refer to our particle birth location
point = om.MPoint(*cmds.xform(q=True, t=True, ws=True))
# Loading the curve, in case we didn't have it already
curve = om.MObject()
sel = om.MSelectionList()
om.MGlobal.getSelectionListByName("curveShape1", sel)
sel.getDependNode(0, curve)
curveFn = om.MFnNurbsCurve(curve)
# Have to use pointers to get double data
double1 = om.MScriptUtil(0.0)
double2 = om.MScriptUtil(0.0)
ptr1 = double1.asDoublePtr()
ptr2 = double2.asDoublePtr()
# Get the parameter range of the curve
curveFn.getKnotDomain(ptr1, ptr2)
start = double1.getDouble(ptr1)
end = double2.getDouble(ptr2)
# Get the parameter value for our point location
curveFn.getParamAtPoint(point, ptr1, 0.5)
param = double1.getDouble(ptr1)
# Normalize to 0-1
norm = param / (end-start)
This might get you the scaled value of the point on the curve?
On Fri, Jun 13, 2014 at 5:47 PM, Eric Corriel <[email protected]>
wrote:
> Imagine there's:
>
> - curve1
> - particles1 emitted from curve1
> - black to white ramp1
>
>
> I'd like to:
>
> - use a black to white ramp to control the lifespan of particles being
> emitted along a curve
> - by somehow mapping particle1.lifespanPP to ramp1.getValueAtPosition()
> - where the argument passed into getValueAtPosition() is the
> normalized value of where the particle was born on the curve (a float from
> 0 to 1, where 0 represents one end of the curve and 1 represents the other
> end)
>
> So the two problems are:
>
> 1. Find, on a scale of 0 to 1, where a particle was born along the
> length of the curve
> 2. Once that's found, how can I use the ramp as something like a
> lookup table to get a value to set particle1.lifespanPP?
>
> Any help would be greatly appreciated. If there's an easier way of doing
> this, I'm all ears. Also greatly appreciated would be explaining this to
> me like I'm 5…Thanks!
>
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