static void Main(string[] args)
{
var width = 200;
var height = 100;
var samples = 100;
var camera = new Camera();
var rand = new Random();
var world = new HitableList();
world.Add(new Sphere(
new Vector3(0, 0, -1),
0.5f
));
world.Add(new Sphere(
new Vector3(0, -100.5f, -1),
100f
));
using (var image = new Image <Rgba32>(width, height))
{
for (int j = height - 1; j >= 0; j--)
{
for (int i = 0; i < width; i++)
{
var col = new Vector3(0);
for (int s = 0; s < samples; s++)
{
// the horizontal distance from the origin as a float between 0 and 1
// with a random number between 0 and 1 added to it for each sample
var u = (i + (float)rand.NextDouble()) / (float)width;
// the vertical distance from the origin as a float between 0 and 1
// with a random number between 0 and 1 added to it for each sample
var v = 1 - ((j + (float)rand.NextDouble()) / (float)height);
var r = camera.GetRay(u, v);
col += Color(r, world);
}
// generates the average color over all the samples
col /= (float)samples;
// gamma correction
// basically fixes the color
// this is gamma 2 so you raise the color to the power 1/gamma which in this case means sqrt
col = new Vector3((float)Math.Sqrt(col.X), (float)Math.Sqrt(col.Y), (float)Math.Sqrt(col.Z));
image[i, j] = new Rgba32(col);
}
}
image.Save("images/gammacorr.png");
}
Vector3 Color(Ray r, Hitable world)
{
var rec = new HitRecord();
if (world.Hit(r, 0.001f, float.MaxValue, rec))
{
// generates a random point in a sphere that is tangent to the hitpoint
var target = rec.P + rec.Normal + RandomInUnitSphere();
// sends out a new ray in the direction of the target from the hitpoint
// returns when one of the subsequent rays either hits the sky or the t values become so close that they're basically zero
// the 0.5 means that 50% of the rays are absorbed into the material
return(0.5f * Color(new Ray(rec.P, target - rec.P), world));
}
else
{
// this creates the sky
var unitDirection = Vector3.Normalize(r.Direction); // makes direction vector go between -1 and 1
var t = 0.5f * (unitDirection.Y + 1.0f); // scales vector so it goes between 0 and 1
return((1 - t) * new Vector3(1f) + t * new Vector3(0.5f, 0.7f, 1.0f)); // linearly interpolates color
}
}
Vector3 RandomInUnitSphere()
{
var p = new Vector3();
do
{
// This generates a random point with XYZ between -1 and 1
p = 2 * new Vector3((float)rand.NextDouble(), (float)rand.NextDouble(), (float)rand.NextDouble()) - new Vector3(1);
} while (p.LengthSquared() >= 1f);
return(p);
}
}
