static float3 Trace(Ray r, int depth, ref int inoutRayCount, ref SpheresSoA spheres, NativeArray <Material> materials, ref uint randState, bool doMaterialE = true)
{
Hit rec = default(Hit);
int id = 0;
++inoutRayCount;
if (HitWorld(r, kMinT, kMaxT, ref rec, ref id, ref spheres))
{
Ray scattered;
float3 attenuation;
float3 lightE;
var mat = materials[id];
var matE = mat.emissive;
if (depth < kMaxDepth && Scatter(mat, r, rec, out attenuation, out scattered, out lightE, ref inoutRayCount, ref spheres, materials, ref randState))
{
#if DO_LIGHT_SAMPLING
if (!doMaterialE)
{
matE = new float3(0, 0, 0);
}
doMaterialE = (mat.type != Material.Type.Lambert);
#endif
return(matE + lightE + attenuation * Trace(scattered, depth + 1, ref inoutRayCount, ref spheres, materials, ref randState, doMaterialE));
}
else
{
return(matE);
}
}
else
{
// sky
float3 unitDir = r.dir;
float t = 0.5f * (unitDir.y + 1.0f);
return(((1.0f - t) * new float3(1.0f, 1.0f, 1.0f) + t * new float3(0.5f, 0.7f, 1.0f)) * 0.3f);
}
}
static bool Scatter(Material mat, Ray r_in, Hit rec, out float3 attenuation, out Ray scattered, out float3 outLightE, ref int inoutRayCount, ref SpheresSoA spheres, NativeArray <Material> materials, ref uint randState)
{
outLightE = new float3(0, 0, 0);
if (mat.type == Material.Type.Lambert)
{
// random point inside unit sphere that is tangent to the hit point
float3 target = rec.pos + rec.normal + MathUtil.RandomUnitVector(ref randState);
scattered = new Ray(rec.pos, normalize(target - rec.pos));
attenuation = mat.albedo;
// sample lights
#if DO_LIGHT_SAMPLING
for (int j = 0; j < spheres.emissiveCount; ++j)
{
int i = spheres.emissives[j];
//@TODO if (&mat == &smat)
// continue; // skip self
//var s = spheres[i];
float3 scenter = new float3(spheres.centerX[i], spheres.centerY[i], spheres.centerZ[i]);
float sqRradius = spheres.sqRadius[i];
// create a random direction towards sphere
// coord system for sampling: sw, su, sv
float3 sw = normalize(scenter - rec.pos);
float3 su = normalize(cross(abs(sw.x) > 0.01f ? new float3(0, 1, 0) : new float3(1, 0, 0), sw));
float3 sv = cross(sw, su);
// sample sphere by solid angle
float cosAMax = sqrt(max(0.0f, 1.0f - sqRradius / lengthSquared(rec.pos - scenter)));
float eps1 = RandomFloat01(ref randState), eps2 = RandomFloat01(ref randState);
float cosA = 1.0f - eps1 + eps1 * cosAMax;
float sinA = sqrt(1.0f - cosA * cosA);
float phi = 2 * PI * eps2;
float3 l = su * cos(phi) * sinA + sv * sin(phi) * sinA + sw * cosA;
l = normalize(l);
// shoot shadow ray
Hit lightHit = default(Hit);
int hitID = 0;
++inoutRayCount;
if (HitWorld(new Ray(rec.pos, l), kMinT, kMaxT, ref lightHit, ref hitID, ref spheres) && hitID == i)
{
float omega = 2 * PI * (1 - cosAMax);
float3 rdir = r_in.dir;
float3 nl = dot(rec.normal, rdir) < 0 ? rec.normal : -rec.normal;
outLightE += (mat.albedo * materials[i].emissive) * (max(0.0f, dot(l, nl)) * omega / PI);
}
}
#endif
return(true);
}
else if (mat.type == Material.Type.Metal)
{
float3 refl = reflect(r_in.dir, rec.normal);
// reflected ray, and random inside of sphere based on roughness
scattered = new Ray(rec.pos, normalize(refl + mat.roughness * RandomInUnitSphere(ref randState)));
attenuation = mat.albedo;
return(dot(scattered.dir, rec.normal) > 0);
}
else if (mat.type == Material.Type.Dielectric)
{
float3 outwardN;
float3 rdir = r_in.dir;
float3 refl = reflect(rdir, rec.normal);
float nint;
attenuation = new float3(1, 1, 1);
float3 refr;
float reflProb;
float cosine;
if (dot(rdir, rec.normal) > 0)
{
outwardN = -rec.normal;
nint = mat.ri;
cosine = mat.ri * dot(rdir, rec.normal);
}
else
{
outwardN = rec.normal;
nint = 1.0f / mat.ri;
cosine = -dot(rdir, rec.normal);
}
if (Refract(rdir, outwardN, nint, out refr))
{
reflProb = Schlick(cosine, mat.ri);
}
else
{
reflProb = 1;
}
if (RandomFloat01(ref randState) < reflProb)
{
scattered = new Ray(rec.pos, normalize(refl));
}
else
{
scattered = new Ray(rec.pos, normalize(refr));
}
}
else
{
attenuation = new float3(1, 0, 1);
scattered = default(Ray);
return(false);
}
return(true);
}
static bool HitWorld(Ray r, float tMin, float tMax, ref Hit outHit, ref int outID, ref SpheresSoA spheres)
{
outID = spheres.HitSpheres(ref r, tMin, tMax, ref outHit);
return(outID != -1);
}
public Test()
{
s_SpheresSoA = new SpheresSoA(s_SpheresData.Length);
}