public TriangleLight(int tri, TriangleMeshLight meshlight) { tri3 = 3 * tri; this.meshlight = meshlight; int a = meshlight.triangles[tri3 + 0]; int b = meshlight.triangles[tri3 + 1]; int c = meshlight.triangles[tri3 + 2]; Point3 v0p = meshlight.getPoint(a); Point3 v1p = meshlight.getPoint(b); Point3 v2p = meshlight.getPoint(c); ng = Point3.normal(v0p, v1p, v2p); area = 0.5f * ng.Length(); ng.normalize(); }
public void getSamples(ShadingState state) { if (meshlight.numSamples == 0) { return; } Vector3 n = state.getNormal(); Point3 p = state.getPoint(); // vector towards each vertex of the light source Vector3 p0 = Point3.sub(meshlight.getPoint(meshlight.triangles[tri3 + 0]), p, new Vector3()); // cull triangle if it is facing the wrong way if (Vector3.dot(p0, ng) >= 0) { return; } Vector3 p1 = Point3.sub(meshlight.getPoint(meshlight.triangles[tri3 + 1]), p, new Vector3()); Vector3 p2 = Point3.sub(meshlight.getPoint(meshlight.triangles[tri3 + 2]), p, new Vector3()); // if all three vertices are below the hemisphere, stop if (Vector3.dot(p0, n) <= 0 && Vector3.dot(p1, n) <= 0 && Vector3.dot(p2, n) <= 0) { return; } p0.normalize(); p1.normalize(); p2.normalize(); float dot = Vector3.dot(p2, p0); Vector3 h = new Vector3(); h.x = p2.x - dot * p0.x; h.y = p2.y - dot * p0.y; h.z = p2.z - dot * p0.z; float hlen = h.Length(); if (hlen > 1e-6f) { h.div(hlen); } else { return; } Vector3 n0 = Vector3.cross(p0, p1, new Vector3()); float len0 = n0.Length(); if (len0 > 1e-6f) { n0.div(len0); } else { return; } Vector3 n1 = Vector3.cross(p1, p2, new Vector3()); float len1 = n1.Length(); if (len1 > 1e-6f) { n1.div(len1); } else { return; } Vector3 n2 = Vector3.cross(p2, p0, new Vector3()); float len2 = n2.Length(); if (len2 > 1e-6f) { n2.div(len2); } else { return; } float cosAlpha = MathUtils.clamp(-Vector3.dot(n2, n0), -1.0f, 1.0f); float cosBeta = MathUtils.clamp(-Vector3.dot(n0, n1), -1.0f, 1.0f); float cosGamma = MathUtils.clamp(-Vector3.dot(n1, n2), -1.0f, 1.0f); float alpha = (float)Math.Acos(cosAlpha); float beta = (float)Math.Acos(cosBeta); float gamma = (float)Math.Acos(cosGamma); float area = alpha + beta + gamma - (float)Math.PI; float cosC = MathUtils.clamp(Vector3.dot(p0, p1), -1.0f, 1.0f); float salpha = (float)Math.Sin(alpha); float product = salpha * cosC; // use lower sampling depth for diffuse bounces int samples = state.getDiffuseDepth() > 0 ? 1 : meshlight.numSamples; Color c = Color.mul(area / samples, meshlight.radiance); for (int i = 0; i < samples; i++) { // random offset on unit square double randX = state.getRandom(i, 0, samples); double randY = state.getRandom(i, 1, samples); float phi = (float)randX * area - alpha + (float)Math.PI; float sinPhi = (float)Math.Sin(phi); float cosPhi = (float)Math.Cos(phi); float u = cosPhi + cosAlpha; float v = sinPhi - product; float q = (-v + cosAlpha * (cosPhi * -v + sinPhi * u)) / (salpha * (sinPhi * -v - cosPhi * u)); float q1 = 1.0f - q * q; if (q1 < 0.0f) { q1 = 0.0f; } float sqrtq1 = (float)Math.Sqrt(q1); float ncx = q * p0.x + sqrtq1 * h.x; float ncy = q * p0.y + sqrtq1 * h.y; float ncz = q * p0.z + sqrtq1 * h.z; dot = p1.dot(ncx, ncy, ncz); float z = 1.0f - (float)randY * (1.0f - dot); float z1 = 1.0f - z * z; if (z1 < 0.0f) { z1 = 0.0f; } Vector3 nd = new Vector3(); nd.x = ncx - dot * p1.x; nd.y = ncy - dot * p1.y; nd.z = ncz - dot * p1.z; nd.normalize(); float sqrtz1 = (float)Math.Sqrt(z1); Vector3 result = new Vector3(); result.x = z * p1.x + sqrtz1 * nd.x; result.y = z * p1.y + sqrtz1 * nd.y; result.z = z * p1.z + sqrtz1 * nd.z; // make sure the sample is in the right hemisphere - facing in // the right direction if (Vector3.dot(result, n) > 0 && Vector3.dot(result, state.getGeoNormal()) > 0 && Vector3.dot(result, ng) < 0) { // compute intersection with triangle (if any) Ray shadowRay = new Ray(state.getPoint(), result); if (!intersectTriangleKensler(shadowRay)) { continue; } LightSample dest = new LightSample(); dest.setShadowRay(shadowRay); // prepare sample dest.setRadiance(c, c); dest.traceShadow(state); state.addSample(dest); } } }