import math
from OpenGL.GL import *
from OpenGL.GLUT import *
from Vector import *

def drawStrokeString(text, position=None, font=GLUT_STROKE_ROMAN):
    if position:
        glTranslatef(position[0], position[1], position[2])
    for c in text:
        glutStrokeCharacter(font, ord(c))

def drawBitmapString(text, position=None, font=GLUT_BITMAP_TIMES_ROMAN_24):
    if position:
        if len(position) > 2:
            glRasterPos3fv(position)
        else:
            glRasterPos2fv(position)
    for c in text:
        glutBitmapCharacter(font, ord(c))

def drawAxes():
    X_Axis.drawLine();
    drawBitmapString("X",X_Axis,GLUT_BITMAP_TIMES_ROMAN_24);
    Y_Axis.drawLine();
    drawBitmapString("Y",Y_Axis,GLUT_BITMAP_TIMES_ROMAN_24);
    Z_Axis.drawLine();
    drawBitmapString("Z",Z_Axis,GLUT_BITMAP_TIMES_ROMAN_24);

def degreesToRadians(angle):
    return angle * math.pi / 180.0

def radiansToDegrees(angle):
    return angle * 180.0 / math.pi

def computeNormal(v0, v1, v2):
    A = [ v2[0] - v1[0], v2[1] - v1[1], v2[2] - v1[2] ]
    B = [ v0[0] - v1[0], v0[1] - v1[1], v0[2] - v1[2] ]
    product = [ A[1] * B[2] - A[2] * B[1],
                A[2] * B[0] - A[0] * B[2],
                A[0] * B[1] - A[1] * B[0] ]
    length = math.sqrt(product[0]*product[0] + product[1]*product[1] + product[2]*product[2])
    if (length == 0):      # If there's a problem,
        return Y_Axis   # return an arbitrary result
    else:
        return Vector([ product[0]/length, product[1]/length, product[2]/length ])