WUT_Computer_Science/Programming/TRAK/sightpy/ray.py

from .utils.constants import *
from .utils.vector3 import vec3, extract, rgb
import numpy as np
from functools import reduce as reduce 

RAYS = 0
PRIMARY_RAYS = 0


class Ray:    
    """Info of the ray and the media it's travelling"""
    def __init__(self,origin, dir, depth, n, reflections, transmissions, diffuse_reflections):

        self.origin  = origin   # the point where the ray comes from
        self.dir = dir          # direction of the ray
        self.depth = depth     # ray_depth is the number of the refrections + transmissions/refractions, starting at zero for camera rays
        self.n = n             # ray_n is the index of refraction of the media in which the ray is travelling
        
        # Instead of defining a index of refraction (n) for each wavelenght (computationally expensive) we aproximate defining the index of refraction
        # using a vec3 for red = 630 nm, green 555 nm, blue 475 nm, the most sensitive wavelenghts of human eye.
        
        # Index a refraction is a complex number. 
        # The real part is involved in how much light is reflected and model refraction direction via Snell Law.
        # The imaginary part of n is involved in how much light is reflected and absorbed. For non-transparent materials like metals is usually between (0.1j,3j)
        # and for transparent materials like glass is  usually between (0.j , 1e-7j)


        self.reflections = reflections  #reflections is the number of the refrections, starting at zero for camera rays
        self.transmissions = transmissions  #transmissions is the number of the transmissions/refractions, starting at zero for camera rays
        self.diffuse_reflections = diffuse_reflections  #reflections is the number of the refrections, starting at zero for camera rays
        
        global RAYS 
        RAYS += 1
        if  self.reflections == 0 and self.transmissions == 0 and self.diffuse_reflections == 0:
            global PRIMARY_RAYS
            PRIMARY_RAYS += 1


    def extract(self,hit_check):
        return Ray(self.origin.extract(hit_check), self.dir.extract(hit_check), self.depth,  self.n.extract(hit_check), self.reflections, self.transmissions,self.diffuse_reflections)


class Hit:  
    """Info of the ray-surface intersection"""
    def __init__(self, distance, orientation, material, collider,surface):
        self.distance = distance
        self.orientation = orientation 
        self.material = material
        self.collider = collider
        self.surface = surface
        self.u = None
        self.v = None
        self.N = None
        self.point = None 

    def get_uv(self):
        if self.u is None: #this is for prevent multiple computations of u,v
            self.u, self.v = self.collider.assigned_primitive.get_uv(self)
        return self.u, self.v

    def get_normal(self):
        if self.N is None: #this is for prevent multiple computations of normal
            self.N = self.collider.get_N(self)
        return self.N



def get_raycolor(ray, scene):

    inters = [s.intersect(ray.origin, ray.dir) for s in scene.collider_list]
    distances, hit_orientation = zip(*inters)

    
    # get the shortest distance collision
    nearest = reduce(np.minimum, distances)
    color = rgb(0., 0., 0.)

    
    for (coll, dis , orient) in zip(scene.collider_list, distances, hit_orientation):
        hit_check = (nearest != FARAWAY) & (dis == nearest)

        if np.any(hit_check):  

            material = coll.assigned_primitive.material
            hit_info = Hit(extract(hit_check,dis) , extract(hit_check,orient), material, coll, coll.assigned_primitive)

            
            
            cc = material.get_color(scene,  ray.extract(hit_check), hit_info)
            color += cc.place(hit_check)

    return color
    



def get_distances(ray, scene): #Used for debugging ray-surface collisions. Return a grey map of objects distances.

    inters = [s.intersect(ray.origin, ray.dir) for s in scene.collider_list]
    distances, hit_orientation = zip(*inters)
    # get the shortest distance collision
    nearest = reduce(np.minimum, distances)
    
    max_r_distance = 10
    r_distance = np.where(nearest <= max_r_distance, nearest, max_r_distance)
    norm_r_distance = r_distance/max_r_distance
    return rgb(norm_r_distance, norm_r_distance, norm_r_distance)

def get_rays():
    return RAYS, PRIMARY_RAYS