/* * The MIT License * * Copyright 2023 akava. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package ptjava; import java.util.concurrent.ThreadLocalRandom; interface Sampler { Colour Sample(Scene scene, Ray ray, ThreadLocalRandom rand); } class DefaultSampler implements Sampler { int FirstHitSamples; int MaxBounces; boolean DirectLighting; boolean SoftShadows; LightMode lightMode; SpecularMode specularMode; DefaultSampler() { } public DefaultSampler(int firstHitSamples, int maxBounces) { this.FirstHitSamples = firstHitSamples; this.MaxBounces = maxBounces; this.DirectLighting = true; this.SoftShadows = true; this.lightMode = LightMode.LightModeRandom; this.specularMode = SpecularMode.SpecularModeNaive; } public static DefaultSampler NewSampler(int firstHitSamples, int maxBounces) { return new DefaultSampler(firstHitSamples, maxBounces); } public static DefaultSampler NewDirectSampler() { return new DefaultSampler(1, 0); } @Override public Colour Sample(Scene scene, Ray ray, ThreadLocalRandom rand) { return sample(scene, ray, true, FirstHitSamples, 0, rand); } Colour sample(Scene scene, Ray ray, boolean emission, int samples, int depth, ThreadLocalRandom rand) { if (depth > MaxBounces) { return Colour.Black; } Hit hit = scene.Intersect(ray); if (!hit.Ok()) { return sampleEnvironment(scene, ray); } var info = hit.Info(ray); var material = info.material; var result = Colour.Black; if (material.Emittance > 0) { if (this.DirectLighting && !emission) { return Colour.Black; } result = result.Add(material.Color.MulScalar(material.Emittance * samples)); } int n = (int) Math.sqrt(samples); BounceType ma, mb; if (this.specularMode == SpecularMode.SpecularModeAll || (depth == 0 && this.specularMode == SpecularMode.SpecularModeFirst)) { ma = BounceType.BounceTypeDiffuse; mb = BounceType.BounceTypeSpecular; } else { ma = BounceType.BounceTypeAny; mb = BounceType.BounceTypeAny; } for (int u = 0; u < n; u++) { for (int v = 0; v < n; v++) { double fu = (u + rand.nextDouble()) / n; double fv = (v + rand.nextDouble()) / n; for (BounceType mode = ma; mode.compareTo(mb) <= 0; mode = mode.next()) { var bounceResult = ray.Bounce(info, fu, fv, mode, rand); Ray newRay = bounceResult.getRay(); boolean reflected = bounceResult.isReflected(); double p = bounceResult.getProbability(); if (mode == BounceType.BounceTypeAny) { p = 1.0; } if (p > 0) { var indirect = sample(scene, newRay, reflected, 1, depth + 1, rand); if (reflected) { Colour tinted = indirect.Mix(material.Color.Mul(indirect), material.Tint); result = result.Add(tinted.MulScalar(p)); } else { Colour direct = Colour.Black; if (DirectLighting) { direct = sampleLights(scene, info.Ray, rand); } result = result.Add(material.Color.Mul(direct.Add(indirect)).MulScalar(p)); } } if (mode == mb) { break; } } } } return result.DivScalar(n * n); } Colour sampleEnvironment(Scene scene, Ray ray) { if (scene.Texture != null) { Vector d = ray.Direction; double u = Math.atan2(d.getZ(), d.getX()) + scene.TextureAngle; double v = Math.atan2(d.getY(), Math.sqrt(d.getX() * d.getX() + d.getZ() * d.getZ())); u = (u + Math.PI) / (2 * Math.PI); v = (v + Math.PI / 2) / Math.PI; return scene.Texture.Sample(u, v); } return scene.Color; } Colour sampleLights(Scene scene, Ray n, ThreadLocalRandom rand) { int nLights = scene.Lights.length; if (nLights == 0) { return Colour.Black; } if (lightMode == LightMode.LightModeAll) { Colour result = new Colour(); for (IShape light : scene.Lights) { if (light != null) { result = result.Add(sampleLight(scene, n, rand, light)); } } return result; } else { // pick a random light IShape light = scene.Lights[rand.nextInt(nLights)]; return sampleLight(scene, n, rand, light).MulScalar((double)nLights); } } Colour sampleLight(Scene scene, Ray n, ThreadLocalRandom rand, IShape light) { Vector center; double radius; if (light instanceof Sphere) { radius = ((Sphere) light).Radius; center = ((Sphere) light).Center; } else { Box box = light.BoundingBox(); radius = box.OuterRadius(); center = box.Center(); } Vector point = center; if (this.SoftShadows) { while (true) { double x = rand.nextDouble() * 2 - 1; double y = rand.nextDouble() * 2 - 1; if (x * x + y * y <= 1) { Vector l = center.Sub(n.Origin).Normalize(); Vector u = l.Cross(Vector.RandomUnitVector(rand)).Normalize(); Vector v = l.Cross(u); point = center.Add(u.MulScalar(x * radius)).Add(v.MulScalar(y * radius)); break; } } } // Construct ray toward light point Ray ray = new Ray(n.Origin, point.Sub(n.Origin).Normalize()); // Get cosine term double diffuse = ray.Direction.Dot(n.Direction); if (diffuse <= 0) { return Colour.Black; } // Check for light visibility Hit hit = scene.Intersect(ray); if (!hit.Ok() || hit.Shape != light) { return Colour.Black; } // Compute solid angle (hemisphere coverage) double hyp = center.Sub(n.Origin).Length(); double opp = radius; double theta = Math.asin(opp / hyp); double adj = opp / Math.tan(theta); double d = Math.cos(theta) * adj; double r = Math.sin(theta) * adj; double coverage = (r * r) / (d * d); if (hyp < opp) { coverage = 1; } coverage = Math.min(coverage, 1); // Get material properties from light Material material = Material.MaterialAt(light, point); // Combine factors double m = material.Emittance * diffuse * coverage; return material.Color.MulScalar(m); } public void SetSpecularMode(SpecularMode sm) { this.specularMode = sm; } public void SetLightMode(LightMode lm) { this.lightMode = lm; } }