FillBetween3d.py

# -*- coding: utf-8 -*-
"""
Created on Fri Jul 12 14:04:23 2019

@author: artmenlope
"""

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
from mpl_toolkits.mplot3d.art3d import Poly3DCollection



def fill_between_3d(ax,x1,y1,z1,x2,y2,z2,mode=1,c='steelblue',alpha=0.6):
    
    """
    
    Function similar to the matplotlib.pyplot.fill_between function but 
    for 3D plots.
       
    input:
        
        ax -> The axis where the function will plot.
        
        x1 -> 1D array. x coordinates of the first line.
        y1 -> 1D array. y coordinates of the first line.
        z1 -> 1D array. z coordinates of the first line.
        
        x2 -> 1D array. x coordinates of the second line.
        y2 -> 1D array. y coordinates of the second line.
        z2 -> 1D array. z coordinates of the second line.
    
    modes:

        mode = 1 -> Fill between the lines using the shortest distance between 
                    both. Makes a lot of single trapezoids in the diagonals 
                    between lines and then adds them into a single collection.
                    
        mode = 2 -> Uses the lines as the edges of one only 3d polygon.
           
    Other parameters (for matplotlib): 
        
        c -> the color of the polygon collection.
        alpha -> transparency of the polygon collection.
        
    """

    if mode == 1:
        
        for i in range(len(x1)-1):
            
            verts = [(x1[i],y1[i],z1[i]), (x1[i+1],y1[i+1],z1[i+1])] + \
                    [(x2[i+1],y2[i+1],z2[i+1]), (x2[i],y2[i],z2[i])]
            
            ax.add_collection3d(Poly3DCollection([verts],
                                                 alpha=alpha,
                                                 linewidths=0,
                                                 color=c))

    if mode == 2:
        
        verts = [(x1[i],y1[i],z1[i]) for i in range(len(x1))] + \
                [(x2[i],y2[i],z2[i]) for i in range(len(x2))]
                
        ax.add_collection3d(Poly3DCollection([verts],alpha=alpha,color=c))