Triangle.py

from Vector3D import *
import math
class Triangle:
    def __init__(self,v1,v2,v3,color=Vector(255,0,0)): #3d Vectors represent colors!
        self.v1=v1
        self.v2=v2
        self.v3=v3
        self._normal=None #STARTING AT LEFT
        self._rnormal=None #normal from right
        self._centre=(v1+v2+v3)/3
        self.color=color

    @property
    def normal(self):
        if (self._normal is None):
            self._normal = (self.v3-self.v1)*(self.v2-self.v1)
        return self._normal
    @property
    def rnormal(self):
        if (self._rnormal is None):
            if (self._normal is None):
                self._rnormal = (self.v2-self.v1)*(self.v3-self.v1)
            else:
                self._rnormal = -self.normal
        return self._rnormal
    @property
    def centre(self):
        if (self._centre is None):
            self._centre = (self.v1+self.v2+self.v3)/3
        return self._centre
    def __repr__(self):
        return "Triangle({},{},{},{})".format(self.v1,self.v2,self.v3,self.color)
    
    def normal_angle(self,point): #ONLY FOR RENDERER! MAY BE DEPRECATED
        """the angle of the normal with another vector"""
        return self.normal.angle(point-self.centre)
    def shade(self,light):
        """shading method"""
        self.shadeVal=(self.normal.angle(light-self.centre)/math.pi)*255
        self.color=Vector(self.color.x - self.shadeVal,self.color.y - self.shadeVal,self.color.z - self.shadeVal)#