public bool hit(ray r, float t_min, float t_max, hit_record rec)
{
vec3 oc = r.Origin - center;
float a = vec3.dot(r.Direction, r.Direction);
float b = vec3.dot(oc, r.Direction);
float c = vec3.dot(oc, oc) - radius * radius;
float discriminant = b * b - a * c;
if (discriminant > 0)
{
float temp = (-b - (float)Math.Sqrt(discriminant)) / a;
if (temp < t_max && temp > t_min)
{
rec.t = temp;
rec.p = r.point_at_parameter(rec.t);
rec.normal = (rec.p - center) / radius;
return(true);
}
temp = (-b + (float)Math.Sqrt(discriminant)) / a;
if (temp < t_max && temp > t_min)
{
rec.t = temp;
rec.p = r.point_at_parameter(rec.t);
rec.normal = (rec.p - center) / radius;
return(true);
}
}
return(false);
}
public bool hit(ray r, float t_min, float t_max, hit_record rec)
{
hit_record temp_rec = new hit_record();
bool hit_anything = false;
double closest_so_far = t_max;
for (int i = 0; i < list_size; i++)
{
if (list[i].hit(r, t_min, (float)closest_so_far, temp_rec))
{
hit_anything = true;
closest_so_far = temp_rec.t;
rec = temp_rec;
}
}
return(hit_anything);
}
static void Main(string[] args)
{
int nx = 200;
int ny = 100;
float u, v;
ray r;
vec3 color;
int nr, ng, nb;
string dir = Directory.GetCurrentDirectory();
string fileName = @"\out.ppm";
StreamWriter sw = File.CreateText(dir + fileName);
sw.WriteLine("P3");
sw.WriteLine(nx.ToString() + " " + ny.ToString());
sw.WriteLine("255");
vec3 lower_left_corner = new vec3(-2, -1, -1); //offset
vec3 horizontal = new vec3(4, 0, 0); //total width
vec3 verticle = new vec3(0, 2, 0); //total height
vec3 origin = new vec3(0, 0, 0); //camera position
for (int j = ny - 1; j >= 0; j--)
{
for (int i = 0; i < nx; i++)
{
u = (i * 1.0f) / nx;
v = (j * 1.0f) / ny;
r = new ray(origin, lower_left_corner + horizontal * u + verticle * v);
color = GetColor(r);
nr = (int)(255.99 * color.r);
ng = (int)(255.99 * color.g);
nb = (int)(255.99 * color.b);
sw.WriteLine(nr.ToString() + " " + ng.ToString() + " " + nb.ToString());
}
}
sw.Flush();
sw.Close();
}
static vec3 GetColor(ray r, hitable world)
{
hit_record rec = new hit_record();
//float value = -1;
//bool hit = HitSphere(new vec3(0, 0, -1), 0.5f, r, out value);
if (world.hit(r, 0.0f, float.MaxValue, rec))
{
return(new vec3(1 + rec.normal.x, 1 + rec.normal.y, 1 + rec.normal.z) * 0.5f); //[-1,1]-->[0,2]-->[0,1]
}
else
{
vec3 Normal = (r.point_at_parameter(value) - new vec3(0, 0, -1)).Normalize(); //normal:[-1,1]
return(new vec3(1 + Normal.x, 1 + Normal.y, 1 + Normal.z) * 0.5f); //[-1,1]-->[0,2]-->[0,1]
}
vec3 normalizedDir = r.Direction.Normalize();
float y = normalizedDir.y + 1; //[-1,1]-->[0,2]
float t = 0.5f * y; //[0,2]-->[0,1]
vec3 color_start = new vec3(1, 1, 1); //white
vec3 color_end = new vec3(0.5f, 0.7f, 1); //light blue
return(color_start * (1 - t) + color_end * t); //linear interpolate
}
