public static double intersection_ray_sphere(double[] position, double[] vector, sphere_class sphere)
{
double output_t = double.PositiveInfinity;
position = vector_class.vector_subtract(position, sphere.center);
double a = vector_class.vector_dot_product(vector, vector);
double b = 2 * vector_class.vector_dot_product(vector, position);
double c = vector_class.vector_dot_product(position, position) - (sphere.radius * sphere.radius);
double discriminant = b * b - 4 * a * c;
if (discriminant < 0)
{
return(output_t);
}
double distance_square_root = System.Math.Sqrt(discriminant);
double q = 0;
if (b < 0)
{
q = (-b - distance_square_root) * 0.5;
}
else
{
q = (-b + distance_square_root) * 0.5;
}
double t0 = q / a;
double t1 = c / q;
if (t0 > t1)
{
double temporary = t0;
t0 = t1;
t1 = temporary;
}
if (t1 < 0)
{
return(output_t);
}
if (t0 < 0)
{
output_t = t1;
return(output_t);
}
else
{
output_t = t0;
return(output_t);
}
}
private void read_spheres()
{
while (text_read_letter() == 's')
{
sphere_class sphere_temporary;
sphere_temporary = new sphere_class();
for (int i = 0; i < 3; i++)
{
sphere_temporary.center[i] = text_read_number();
}
sphere_temporary.radius = text_read_number();
sphere_temporary.material_index = (int)text_read_number();
sphere.Add(sphere_temporary);
}
}
public double[] get_next_direction_sphere(double[] input_position, double[] input_vector, sphere_class input_sphere, ref double incidence_ior, ref double[] multiplier)
{
double[] output_vector = new double[3];
double[] random_vector = new double[3];
double[] sphere_normal = new double[3];
double[] u = new double[3];
double[] v = new double[3];
double a, b, c, angle, radius;
angle = 2 * System.Math.PI * random.NextDouble();
radius = System.Math.Sqrt(random.NextDouble());
a = System.Math.Sin(angle) * radius;
b = System.Math.Cos(angle) * radius;
c = System.Math.Sqrt(1.0 - (a * a + b * b));
sphere_normal = input_sphere.get_normal(input_position);
if (vector_class.vector_dot_product(sphere_normal, input_vector) > 0)
{
sphere_normal = vector_class.vector_negative(sphere_normal);
}
double[] temporary = new double[3];
for (int i = 0; i < 3; i++)
{
temporary[i] = random.NextDouble();
}
u = vector_class.vector_cross_product(sphere_normal, temporary);
v = vector_class.vector_cross_product(sphere_normal, u);
u = vector_class.vector_cross_product(sphere_normal, v);
u = vector_class.vector_unitize(u);
v = vector_class.vector_unitize(v);
random_vector = vector_class.vector_add(vector_class.vector_add(vector_class.vector_scale(v, b),
vector_class.vector_scale(u, a)),
vector_class.vector_scale(sphere_normal, c));
if (random.NextDouble() * (reflectivity_mean + refractivity_mean) < reflectivity_mean) //reflect
{
output_vector = vector_class.vector_average(random_vector,
get_reflection(input_vector, sphere_normal),
reflect_glossiness);
for (int n = 0; n < 3; n++)
{
multiplier[n] *= color[n].reflectivity;
}
}
else //refract
{
output_vector = vector_class.vector_average(vector_class.vector_negative(random_vector),
get_refraction(input_vector, sphere_normal, incidence_ior, ref multiplier),
refract_glossiness);
for (int n = 0; n < 3; n++)
{
multiplier[n] *= color[n].refractivity;
}
incidence_ior = refractive_index;
}
return(output_vector);
}
