You can color spline primitives along their length by setting root and tip colors using custom shader parameters. Root and tip colors appear in the rendered Description, but not in the XGen preview. 
	 
- Click the 
		  Preview/Output tab, and in the 
		  Custom Shader Parameters section, do the following: 
		  - In the space beside Name, type tip_color. 
			 
- From the drop-down list beside 
				Name, select 
				color. 
			 
- Click 
				 to create the parameter. to create the parameter.
 The 
			  tip_color parameter appears in the 
			 Custom Shader Parameters. 
		   
- Repeat step 
		  1 to create a parameter named 
		   root_color. 
		  Use an expression to add color for the tip and root color. 
		   
- Click this icon 
		   beside the parameters to open the 
		  XGen Expression Editor. beside the parameters to open the 
		  XGen Expression Editor.
- In the 
		  XGen Expression Editor, click the 
		  Samples tab. 
		
-  Click the 
		  + 
		   beside 
		  Global and then 
		  + 
		   beside 
		  UI. 
		
- From the expression list that appears, click a color-related expression such as 
		  color_green. 
		
- Click 
		  Accept. 
		  The 
			 tip_color parameter is now set to green. 
		   
- Click the color swatch to set a new color. 
		
- Repeat steps 4 to 8 for 
		  root_color. 
		
- Launch a renderer to render your Description.