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 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);
}
}
}
