matrix.py

import math

def make_bezier():
    return [
        [-1, 3, -3, 1],
        [3, -6, 3, 0],
        [-3, 3, 0, 0],
        [1, 0, 0, 0]
    ]

def make_hermite():
    return [
        [2, -3, 0, 1],
        [-2, 3, 0, 0],
        [1, -2, 1, 0],
        [1, -1, 0, 0]
    ]

def generate_curve_coefs( p0, p1, p2, p3, t ):
    coefs = [[p0, p1, p2, p3]]
    if t == 'hermite':
        curve = make_hermite()
    else:
        curve = make_bezier()

    matrix_mult(curve, coefs)
    return coefs

def make_translate( x, y, z ):
    t = new_matrix()
    ident(t)
    t[3][0] = x
    t[3][1] = y
    t[3][2] = z
    return t

def make_scale( x, y, z ):
    t = new_matrix()
    ident(t)
    t[0][0] = x
    t[1][1] = y
    t[2][2] = z
    return t

def make_rotX( theta ):
    t = new_matrix()
    ident(t)
    t[1][1] = math.cos(theta)
    t[2][1] = -1 * math.sin(theta)
    t[1][2] = math.sin(theta)
    t[2][2] = math.cos(theta)
    return t

def make_rotY( theta ):
    t = new_matrix()
    ident(t)
    t[0][0] = math.cos(theta)
    t[0][2] = -1 * math.sin(theta)
    t[2][0] = math.sin(theta)
    t[2][2] = math.cos(theta)
    return t

def make_rotZ( theta ):
    t = new_matrix()
    ident(t)
    t[0][0] = math.cos(theta)
    t[1][0] = -1 * math.sin(theta)
    t[0][1] = math.sin(theta)
    t[1][1] = math.cos(theta)
    return t

def print_matrix( matrix ):
    s = ''
    for r in range( len( matrix[0] ) ):
        for c in range( len(matrix) ):
            s+= str(matrix[c][r]) + ' '
        s+= '\n'
    print s

def ident( matrix ):
    for r in range( len( matrix[0] ) ):
        for c in range( len(matrix) ):
            if r == c:
                matrix[c][r] = 1
            else:
                matrix[c][r] = 0

def scalar_mult( matrix, s ):
    for r in range( len( matrix[0] ) ):
        for c in range( len(matrix) ):
            matrix[c][r]*= s
            
#m1 * m2 -> m2
def matrix_mult( m1, m2 ):

    point = 0
    for row in m2:
        #get a copy of the next point
        tmp = row[:]
        
        for r in range(4):
            m2[point][r] = (m1[0][r] * tmp[0] +
                            m1[1][r] * tmp[1] +
                            m1[2][r] * tmp[2] +
                            m1[3][r] * tmp[3])
        point+= 1

def new_matrix(rows = 4, cols = 4):
    m = []
    for c in range( cols ):
        m.append( [] )
        for r in range( rows ):
            m[c].append( 0 )
    return m