star.py

#  Sun Mar 01 18:30:17 PST 2015  
#
#  Base star class which is the basic unit of composition for the Galaxy.  In #  the future should pull out the geomatric transformation functions into a
#  base class, but this'll work for now.
#

import sys, math, pygame, random

from Vec3d import Vec3d

class star3D:

    def __init__(self, v = Vec3d(0,0,0), color = (255,255,255), size=1 ):
        self.v = v 
        self.color = color
        self.size  = size

    def rotateX(self, angle):
        """ Rotate the star around the X axis by the given angle in degrees. """
        return star3D(self.v.rotated_around_x(angle), self.color, self.size)

    def rotateXaroundViewer(self, viewer):
        v = self.v - viewer.position
        return star3D(v.rotated_around_x(viewer.direction.get_angle_around_x()), self.color,self.size)
 
    def rotateYaroundViewer(self, viewer):
        v = self.v - viewer.position
        return star3D(v.rotated_around_y(viewer.direction.get_angle_around_y()), self.color,self.size)
 
    def rotateZaroundViewer(self, viewer):
        v = self.v - viewer.position
        return star3D(v.rotated_around_y(viewer.direction.get_angle_around_z()), self.color,self.size)

    def rotateY(self, angle):
        """ Rotate the star around the Y axis by the given angle in degrees. """
        return star3D(self.v.rotated_around_y(angle), self.color, self.size)
 
    def rotateZ(self, angle):
        """ Rotate the star around the Z axis by the given angle in degrees. """
        return star3D(self.v.rotated_around_z(angle), self.color, self.size)
 
    def project(self, win_width, win_height, galaxy_pos, fov, viewer):
        """ Transforms this 3D point to 2D using a perspective projection. """

        # The following chunc of code determines whether the star is
        # outside of the viewers scope by simplistically determining if
        # it is behind the viewer, in which case, it doesn't project the
        # star

        # Note the the viewer is viewer_d along the z axes and looking
        # back (0,0,-1) therefore we use S+V to find the distance
        dist = self.v - viewer.position # distance from star to viewer

        if dist.z > 0:
            return None

        if ((viewer.position.z - self.v.z) + galaxy_pos.z) == 0:
            factor = 0
        else:    
            factor = fov / ((viewer.position.z - self.v.z) + galaxy_pos.z)
        x = (self.v.x+galaxy_pos.x+viewer.position.x) * factor + win_width / 2
        y = -(self.v.y+galaxy_pos.y+viewer.position.y) * factor + win_height / 2
        return star3D(Vec3d(x, y, 0), self.color, self.size)