396 lines
11 KiB
HLSL
396 lines
11 KiB
HLSL
#include "../Source/Config.h"
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inline uint RNG(inout uint state)
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{
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uint x = state;
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x ^= x << 13;
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x ^= x >> 17;
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x ^= x << 15;
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state = x;
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return x;
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}
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float RandomFloat01(inout uint state)
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{
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return (RNG(state) & 0xFFFFFF) / 16777216.0f;
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}
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float3 RandomInUnitDisk(inout uint state)
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{
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float a = RandomFloat01(state) * 2.0f * 3.1415926f;
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float2 xy = float2(cos(a), sin(a));
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xy *= sqrt(RandomFloat01(state));
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return float3(xy, 0);
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}
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float3 RandomInUnitSphere(inout uint state)
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{
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float z = RandomFloat01(state) * 2.0f - 1.0f;
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float t = RandomFloat01(state) * 2.0f * 3.1415926f;
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float r = sqrt(max(0.0, 1.0f - z * z));
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float x = r * cos(t);
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float y = r * sin(t);
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float3 res = float3(x, y, z);
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res *= pow(RandomFloat01(state), 1.0 / 3.0);
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return res;
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}
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float3 RandomUnitVector(inout uint state)
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{
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float z = RandomFloat01(state) * 2.0f - 1.0f;
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float a = RandomFloat01(state) * 2.0f * 3.1415926f;
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float r = sqrt(1.0f - z * z);
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float x = r * cos(a);
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float y = r * sin(a);
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return float3(x, y, z);
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}
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struct Ray
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{
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float3 orig;
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float3 dir;
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};
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Ray MakeRay(float3 orig_, float3 dir_) { Ray r; r.orig = orig_; r.dir = dir_; return r; }
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float3 RayPointAt(Ray r, float t) { return r.orig + r.dir * t; }
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inline bool refract(float3 v, float3 n, float nint, out float3 outRefracted)
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{
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float dt = dot(v, n);
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float discr = 1.0f - nint * nint*(1 - dt * dt);
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if (discr > 0)
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{
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outRefracted = nint * (v - n * dt) - n * sqrt(discr);
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return true;
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}
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return false;
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}
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inline float schlick(float cosine, float ri)
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{
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float r0 = (1 - ri) / (1 + ri);
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r0 = r0 * r0;
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// note: saturate to guard against possible tiny negative numbers
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return r0 + (1 - r0)*pow(saturate(1 - cosine), 5);
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}
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struct Hit
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{
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float3 pos;
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float3 normal;
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float t;
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};
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struct Sphere
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{
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float3 center;
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float radius;
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float invRadius;
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};
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#define MatLambert 0
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#define MatMetal 1
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#define MatDielectric 2
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struct Material
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{
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int type;
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float3 albedo;
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float3 emissive;
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float roughness;
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float ri;
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};
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groupshared Sphere s_GroupSpheres[kCSMaxObjects];
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groupshared Material s_GroupMaterials[kCSMaxObjects];
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groupshared int s_GroupEmissives[kCSMaxObjects];
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struct Camera
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{
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float3 origin;
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float3 lowerLeftCorner;
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float3 horizontal;
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float3 vertical;
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float3 u, v, w;
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float lensRadius;
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};
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Ray CameraGetRay(Camera cam, float s, float t, inout uint state)
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{
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float3 rd = cam.lensRadius * RandomInUnitDisk(state);
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float3 offset = cam.u * rd.x + cam.v * rd.y;
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return MakeRay(cam.origin + offset, normalize(cam.lowerLeftCorner + s * cam.horizontal + t * cam.vertical - cam.origin - offset));
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}
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int HitSpheres(Ray r, int sphereCount, float tMin, float tMax, inout Hit outHit)
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{
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float hitT = tMax;
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int id = -1;
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for (int i = 0; i < sphereCount; ++i)
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{
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Sphere s = s_GroupSpheres[i];
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float3 co = s.center - r.orig;
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float nb = dot(co, r.dir);
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float c = dot(co, co) - s.radius*s.radius;
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float discr = nb * nb - c;
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if (discr > 0)
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{
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float discrSq = sqrt(discr);
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// Try earlier t
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float t = nb - discrSq;
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if (t <= tMin) // before min, try later t!
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t = nb + discrSq;
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if (t > tMin && t < hitT)
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{
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id = i;
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hitT = t;
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}
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}
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}
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if (id != -1)
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{
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outHit.pos = RayPointAt(r, hitT);
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outHit.normal = (outHit.pos - s_GroupSpheres[id].center) * s_GroupSpheres[id].invRadius;
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outHit.t = hitT;
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}
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return id;
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}
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struct Params
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{
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Camera cam;
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int sphereCount;
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int screenWidth;
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int screenHeight;
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int frames;
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float invWidth;
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float invHeight;
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float lerpFac;
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int emissiveCount;
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};
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#define kMinT 0.001f
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#define kMaxT 1.0e7f
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#define kMaxDepth 10
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static int HitWorld(int sphereCount, Ray r, float tMin, float tMax, inout Hit outHit)
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{
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return HitSpheres(r, sphereCount, tMin, tMax, outHit);
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}
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static bool Scatter(int sphereCount, int emissiveCount, int matID, Ray r_in, Hit rec, out float3 attenuation, out Ray scattered, out float3 outLightE, inout int inoutRayCount, inout uint state)
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{
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outLightE = float3(0, 0, 0);
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Material mat = s_GroupMaterials[matID];
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if (mat.type == MatLambert)
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{
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// random point on unit sphere that is tangent to the hit point
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float3 target = rec.pos + rec.normal + RandomUnitVector(state);
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scattered = MakeRay(rec.pos, normalize(target - rec.pos));
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attenuation = mat.albedo;
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// sample lights
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#if DO_LIGHT_SAMPLING
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for (int j = 0; j < emissiveCount; ++j)
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{
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int i = s_GroupEmissives[j];
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if (matID == i)
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continue; // skip self
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Material smat = s_GroupMaterials[i];
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Sphere s = s_GroupSpheres[i];
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// create a random direction towards sphere
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// coord system for sampling: sw, su, sv
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float3 sw = normalize(s.center - rec.pos);
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float3 su = normalize(cross(abs(sw.x)>0.01f ? float3(0, 1, 0) : float3(1, 0, 0), sw));
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float3 sv = cross(sw, su);
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// sample sphere by solid angle
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float cosAMax = sqrt(1.0f - s.radius*s.radius / dot(rec.pos - s.center, rec.pos - s.center));
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float eps1 = RandomFloat01(state), eps2 = RandomFloat01(state);
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float cosA = 1.0f - eps1 + eps1 * cosAMax;
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float sinA = sqrt(1.0f - cosA * cosA);
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float phi = 2 * 3.1415926 * eps2;
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float3 l = su * cos(phi) * sinA + sv * sin(phi) * sinA + sw * cosA;
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// shoot shadow ray
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Hit lightHit;
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++inoutRayCount;
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int hitID = HitWorld(sphereCount, MakeRay(rec.pos, l), kMinT, kMaxT, lightHit);
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if (hitID == i)
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{
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float omega = 2 * 3.1415926 * (1 - cosAMax);
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float3 rdir = r_in.dir;
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float3 nl = dot(rec.normal, rdir) < 0 ? rec.normal : -rec.normal;
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outLightE += (mat.albedo * smat.emissive) * (max(0.0f, dot(l, nl)) * omega / 3.1415926);
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}
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}
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#endif
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return true;
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}
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else if (mat.type == MatMetal)
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{
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float3 refl = reflect(r_in.dir, rec.normal);
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// reflected ray, and random inside of sphere based on roughness
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float roughness = mat.roughness;
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#if DO_MITSUBA_COMPARE
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roughness = 0; // until we get better BRDF for metals
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#endif
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scattered = MakeRay(rec.pos, normalize(refl + roughness*RandomInUnitSphere(state)));
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attenuation = mat.albedo;
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return dot(scattered.dir, rec.normal) > 0;
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}
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else if (mat.type == MatDielectric)
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{
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float3 outwardN;
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float3 rdir = r_in.dir;
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float3 refl = reflect(rdir, rec.normal);
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float nint;
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attenuation = float3(1, 1, 1);
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float3 refr;
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float reflProb;
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float cosine;
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if (dot(rdir, rec.normal) > 0)
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{
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outwardN = -rec.normal;
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nint = mat.ri;
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cosine = mat.ri * dot(rdir, rec.normal);
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}
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else
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{
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outwardN = rec.normal;
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nint = 1.0f / mat.ri;
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cosine = -dot(rdir, rec.normal);
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}
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if (refract(rdir, outwardN, nint, refr))
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{
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reflProb = schlick(cosine, mat.ri);
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}
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else
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{
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reflProb = 1;
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}
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if (RandomFloat01(state) < reflProb)
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scattered = MakeRay(rec.pos, normalize(refl));
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else
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scattered = MakeRay(rec.pos, normalize(refr));
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}
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else
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{
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attenuation = float3(1, 0, 1);
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scattered = MakeRay(float3(0,0,0), float3(0, 0, 1));
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return false;
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}
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return true;
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}
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static float3 Trace(int sphereCount, int emissiveCount, Ray r, inout int inoutRayCount, inout uint state)
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{
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float3 col = 0;
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float3 curAtten = 1;
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bool doMaterialE = true;
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// GPUs don't support recursion, so do tracing iterations in a loop up to max depth
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for (int depth = 0; depth < kMaxDepth; ++depth)
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{
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Hit rec;
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++inoutRayCount;
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int id = HitWorld(sphereCount, r, kMinT, kMaxT, rec);
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if (id >= 0)
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{
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Ray scattered;
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float3 attenuation;
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float3 lightE;
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Material mat = s_GroupMaterials[id];
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float3 matE = mat.emissive;
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if (Scatter(sphereCount, emissiveCount, id, r, rec, attenuation, scattered, lightE, inoutRayCount, state))
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{
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#if DO_LIGHT_SAMPLING
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if (!doMaterialE) matE = 0;
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doMaterialE = (mat.type != MatLambert);
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#endif
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col += curAtten * (matE + lightE);
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curAtten *= attenuation;
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r = scattered;
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}
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else
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{
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col += curAtten * matE;
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break;
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}
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}
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else
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{
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// sky
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#if DO_MITSUBA_COMPARE
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col += curAtten * float3(0.15f, 0.21f, 0.3f); // easier compare with Mitsuba's constant environment light
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#else
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float3 unitDir = r.dir;
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float t = 0.5f*(unitDir.y + 1.0f);
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float3 skyCol = ((1.0f - t)*float3(1.0f, 1.0f, 1.0f) + t * float3(0.5f, 0.7f, 1.0f)) * 0.3f;
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col += curAtten * skyCol;
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#endif
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break;
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}
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}
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return col;
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}
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Texture2D srcImage : register(t0);
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RWTexture2D<float4> dstImage : register(u0);
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StructuredBuffer<Sphere> g_Spheres : register(t1);
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StructuredBuffer<Material> g_Materials : register(t2);
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StructuredBuffer<Params> g_Params : register(t3);
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StructuredBuffer<int> g_Emissives : register(t4);
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RWByteAddressBuffer g_OutRayCount : register(u1);
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[numthreads(kCSGroupSizeX, kCSGroupSizeY, 1)]
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void main(uint3 gid : SV_DispatchThreadID, uint3 tid : SV_GroupThreadID)
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{
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// First, move scene data (spheres, materials, emissive indices) into group shared
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// memory. Do this in parallel; each thread in group copies its own chunk of data.
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uint threadID = tid.y * kCSGroupSizeX + tid.x;
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uint groupSize = kCSGroupSizeX * kCSGroupSizeY;
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uint objCount = g_Params[0].sphereCount;
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uint myObjCount = (objCount + groupSize - 1) / groupSize;
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uint myObjStart = threadID * myObjCount;
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for (uint io = myObjStart; io < myObjStart + myObjCount; ++io)
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{
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if (io < objCount)
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{
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s_GroupSpheres[io] = g_Spheres[io];
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s_GroupMaterials[io] = g_Materials[io];
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}
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if (io < g_Params[0].emissiveCount)
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{
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s_GroupEmissives[io] = g_Emissives[io];
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}
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}
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GroupMemoryBarrierWithGroupSync();
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int rayCount = 0;
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float3 col = 0;
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Params params = g_Params[0];
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uint rngState = (gid.x * 1973 + gid.y * 9277 + params.frames * 26699) | 1;
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for (int s = 0; s < DO_SAMPLES_PER_PIXEL; s++)
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{
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float u = float(gid.x + RandomFloat01(rngState)) * params.invWidth;
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float v = float(gid.y + RandomFloat01(rngState)) * params.invHeight;
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Ray r = CameraGetRay(params.cam, u, v, rngState);
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col += Trace(params.sphereCount, params.emissiveCount, r, rayCount, rngState);
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}
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col *= 1.0f / float(DO_SAMPLES_PER_PIXEL);
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float3 prev = srcImage.Load(int3(gid.xy,0)).rgb;
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col = lerp(col, prev, params.lerpFac);
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dstImage[gid.xy] = float4(col, 1);
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g_OutRayCount.InterlockedAdd(0, rayCount);
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}
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