// Sample an exitant ray
Vec3f DirectionalLight::sampleExitantRay(
const Scene& scene,
const Vec2f& emissionVertexSample,
const Vec2f& raySample,
RaySample& exitantRaySample,
float& emissionVertexPdf) const
{
Vec3f center;
float radius;
boundingSphere(scene.getBBox(), center, radius);
// Center of the disk
center += m_IncidentDirection * radius;
Vec2f pos2D = uniformSampleDisk(raySample, radius);
auto originPdf = 1.f / (pi<float>() * radius * radius);
emissionVertexPdf = 1.f;
auto pdf = originPdf * emissionVertexPdf;
auto matrix = frameY(center, m_IncidentDirection);
auto rayOrigin = Vec3f(matrix * Vec4f(pos2D.x, 0, pos2D.y, 1.f));
exitantRaySample = RaySample(Ray(rayOrigin, -m_IncidentDirection), pdf);
return m_Le;
}
float PerspectiveCamera::generateRay(const Sample& sample,
RayDifferential* ray) const {
float invXRes = mFilm->getInvXResolution();
float invYRes = mFilm->getInvYResolution();
float xNDC = +2.0f * sample.imageX * invXRes - 1.0f;
float yNDC = -2.0f * sample.imageY * invYRes + 1.0f;
float dxNDC = +2.0f * (sample.imageX + 1.0f) * invXRes - 1.0f;
float dyNDC = -2.0f * (sample.imageY + 1.0f) * invYRes + 1.0f;
// from NDC space to view space
// xView = xNDC * zView * tan(fov / 2) * aspectRatio
// yView = yNDC * zView * tan(fov / 2)
// in projection matrix pro,
// pro[0][0] = 1 / (tan(fov / 2) * aspectRatio)
// pro[1][1] = 1 / (tan(fov / 2))
float zView = 1.0f;
float xView = xNDC / mProj[0][0];
float yView = yNDC / mProj[1][1];
Vector3 viewDir = Vector3(xView, yView, zView);
float dxView = dxNDC / mProj[0][0];
Vector3 dxViewDir(dxView, yView, zView);
float dyView = dyNDC / mProj[1][1];
Vector3 dyViewDir(xView, dyView, zView);
if(mLensRadius == 0.0f) {
// view space to world space
ray->o = ray->dxOrigin = ray->dyOrigin = mPosition;
ray->d = mOrientation * normalize(viewDir);
ray->dxDir = mOrientation * normalize(dxViewDir);
ray->dyDir = mOrientation * normalize(dyViewDir);
} else {
// perturb the ray direction for DOF effect
float ft = mFocalDistance / viewDir.z;
Vector3 pFocus = viewDir * ft;
Vector3 pDxFocus = dxViewDir * ft;
Vector3 pDyFocus = dyViewDir * ft;
Vector2 lensSample = mLensRadius *
uniformSampleDisk(sample.lensU1, sample.lensU2);
Vector3 viewOrigin(lensSample.x, lensSample.y, 0.0f);
ray->o = ray->dxOrigin = ray->dyOrigin =
mOrientation * viewOrigin + mPosition;
ray->d = mOrientation * normalize(pFocus - viewOrigin);
ray->dxDir = mOrientation * normalize(pDxFocus - viewOrigin);
ray->dyDir = mOrientation * normalize(pDyFocus - viewOrigin);
}
ray->mint = 1e-3f;
ray->maxt = INFINITY;
ray->depth = 0;
ray->hasDifferential = true;
return 1.0f;
}
Vector3 PerspectiveCamera::samplePosition(const Sample& sample,
Vector3* surfaceNormal, float* pdfArea) const {
Vector3 pCamera;
if (mLensRadius > 0.0f) {
Vector2 lensSample = mLensRadius *
uniformSampleDisk(sample.lensU1, sample.lensU2);
Vector3 viewOrigin(lensSample.x, lensSample.y, 0.0f);
pCamera = mOrientation * viewOrigin + mPosition;
} else {
pCamera = mPosition;
}
if (pdfArea) {
*pdfArea = mLensRadius > 0.0f ?
1.0f / (mLensRadius * mLensRadius * PI) : 1.0f;
}
*surfaceNormal = getLook();
return pCamera;
}
