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 # LightGuide – Defining control points to create parameters variation along the guide

 Last update: 29.07.2026 

This page presents you an example on how to define Control Points to create parameter variation along the guide curve of a Light Guide.

```ironpython
# Light Guide
LightGuide1 = SpeosDes.LightGuide.Create()
            
# Guide curve
Curve_LightGuide = GetRootPart().Curves[4] 
LightGuide1.GuideCurve.Set(Curve_LightGuide)
            
# Body
LightGuide1.BodyProfileDiameter = 5
            
# Prisms orientation
X_Axis =  GetRootPart().Curves[1]
LightGuide1.OpticalAxis.Set(X_Axis)
            
LightGuide1.PrismsOperationType = SpeosDes.LightGuide.EnumPrismsOperationType.Hybrid
LightGuide1.ReverseOpticalAxisDirection = False
            
# Distances
LightGuide1.DistancesType = SpeosDes.LightGuide.EnumDistancesType.Curvilinear
LightGuide1.DistanceStart = 2
LightGuide1.DistanceEnd = 2
            
# Prism geometries
LightGuide1.StepType = "Control points"
            
stepConfig = LightGuide1.StepConfigurations
print "Number of configurations: " + str(stepConfig.Count)
            
for config in LightGuide1.StepConfigurations:
    print "Position: " + str(config.Position) + ", Value: " + str(config.Value)
            
controlPoint = LightGuide1.StepConfigurations.AddNew(0)
controlPoint.Position = 50
controlPoint.Value = 3
            
print "After adding new configuration: "
for config in LightGuide1.StepConfigurations:
    print "Position: " + str(config.Position) + ", Value: " + str(config.Value)
            
# Add after the index
child = LightGuide1.StepConfigurations.AddNew(0)
child.Position = 30
child.Value = 4   
            
LightGuide1.OffsetType = "Constant"
LightGuide1.OffsetValue = 4
            
LightGuide1.StartAngleType = "Input file"
LightGuide1.EndAngleType = "Automatic"
            
LightGuide1.CSVFile = ".\\LightGuide_export.csv"
            
LightGuide1.Compute() 

```