public static byte[] Render(Scene scene, byte[] pixels)
{
var eye = Vec3.Zero;
Num h = MATH.Tan(((fov / 360) * (2 * PI)) / 2) * 2;
Num w = (h * Width) / Height;
for (int y = 0; y != Height; ++y)
{
for (int x = 0; x != Width; ++x)
{
Num xx = x, yy = y, ww = Width, hh = Height;
Vec3 dir;
dir.X = ((xx - (ww / 2.0f)) / ww) * w;
dir.Y = (((hh / 2.0f) - yy) / hh) * h;
dir.Z = -1.0f;
dir = Vec3.Normalize(dir);
Ray r;
r.Org = eye;
r.Dir = dir;
var pixel = trace(r, scene, 0);
int i = (x * 3) + (y * Width * 3);
pixels[i] = (byte)MATH.Min(pixel.X * 255, 255);
pixels[i + 1] = (byte)MATH.Min(pixel.Y * 255, 255);
pixels[i + 2] = (byte)MATH.Min(pixel.Z * 255, 255);
}
}
return(pixels);
}
private static Vec3 trace(Ray ray, Scene scene, int depth)
{
var nearest = Num.MaxValue;
Sphere obj = null;
// search the scene for nearest intersection
foreach (var o in scene.Objects)
{
var distance = Num.MaxValue;
if (Sphere.Intersect(o, ray, out distance))
{
if (distance < nearest)
{
nearest = distance;
obj = o;
}
}
}
if (obj == null)
{
return(Vec3.Zero);
}
var point_of_hit = ray.Org + (ray.Dir * nearest);
var normal = Sphere.Normal(obj, point_of_hit);
bool inside = false;
if (Vec3.Dot(normal, ray.Dir) > 0)
{
inside = true;
normal = -normal;
}
Vec3 color = Vec3.Zero;
var reflection_ratio = obj.Reflection;
foreach (var l in scene.Lights)
{
var light_direction = Vec3.Normalize(l.Position - point_of_hit);
Ray r;
#if BIT64
r.Org = point_of_hit + (normal * 1e-5);
#else
r.Org = point_of_hit + (normal * 1e-5f);
#endif
r.Dir = light_direction;
// go through the scene check whether we're blocked from the lights
bool blocked = false;
foreach (var o in scene.Objects)
{
if (Sphere.Intersect(o, r))
{
blocked = true;
break;
}
}
if (!blocked)
{
color += l.Color
* MATH.Max(0, Vec3.Dot(normal, light_direction))
* obj.Color
* (1.0f - reflection_ratio);
}
}
var rayNormDot = Vec3.Dot(ray.Dir, normal);
Num facing = MATH.Max(0, -rayNormDot);
Num fresneleffect = reflection_ratio + ((1 - reflection_ratio) * MATH.Pow((1 - facing), 5));
// compute reflection
if (depth < maxDepth && reflection_ratio > 0)
{
var reflection_direction = ray.Dir + (normal * 2 * rayNormDot * (-1));
Ray r;
#if BIT64
r.Org = point_of_hit + (normal * 1e-5);
#else
r.Org = point_of_hit + (normal * 1e-5f);
#endif
r.Dir = reflection_direction;
var reflection = trace(r, scene, depth + 1);
color += reflection * fresneleffect;
}
// compute refraction
if (depth < maxDepth && (obj.Transparency > 0))
{
#if BIT64
Num ior = 1.5;
#else
Num ior = 1.5f;
#endif
var CE = Vec3.Dot(ray.Dir, normal) * (-1);
ior = inside ? 1 / ior : ior;
Num eta = 1 / ior;
var GF = (ray.Dir + normal * CE) * eta;
Num sin_t1_2 = 1 - (CE * CE);
Num sin_t2_2 = sin_t1_2 * (eta * eta);
if (sin_t2_2 < 1)
{
var GC = normal * MATH.Sqrt(1 - sin_t2_2);
var refraction_direction = GF - GC;
Ray r;
#if BIT64
r.Org = point_of_hit - (normal * 1e-4);
#else
r.Org = point_of_hit - (normal * 1e-4f);
#endif
r.Dir = refraction_direction;
var refraction = trace(r, scene, depth + 1);
color += refraction * (1 - fresneleffect) * obj.Transparency;
}
}
return(color);
}
public static Vec3 Normal(Sphere sphere, Vec3 pos)
{
return(Vec3.Normalize(pos - sphere.Center));
}