"Spheres in Cancun"

Required:
* Depth should be at least 4. Otherwise last sphere is shaded as black.
Image traced with depth = 5
Required extensions:
* Adaptive antialiasing
* Background image mapping - attached original image employed.

RAY file contents:
SBT-raytracer 1.0

camera {
position = (0,0,-3);
viewdir = (0,0,1);
aspectratio = 1;
updir = (0,1,0);
}


directional_light {
direction = (0, 0, 1);
colour = (1.0, 1.0, 1.0);
}
point_light {
position = (0,0,-.5);
colour = (1.0,1.0,1.0)
constant_attenuation_coeff= 0.25;
linear_attenuation_coeff = 0.003372407;
quadratic_attenuation_coeff = 0.000045492;
}

point_light {
position = (3,0,-4);
colour = (0.1,0.1,0.2)
constant_attenuation_coeff= 0.25;
linear_attenuation_coeff = 0.003372407;
quadratic_attenuation_coeff = 0.000045492;
}

translate(0,0,.6,
scale(1.5,
sphere {
material = {
transmissive = (0.95,0.95,1);
index = 1.15;
}
}))

translate(0,0,1,
scale(.75,
sphere {
material = {
transmissive = (0.95,0.95,0.99);
index = 1.09;
}
}))

translate(0,0,1,
scale(.25,
sphere {
material = {
transmissive = (0.99,0.99,0.95);
index = 1.5;
}
}))