/** \reimpl
*/
void
FeatureLabelSetGeometry::render(RenderContext& rc, double /* clock */) const
{
const float visibleSizeThreshold = 20.0f; // in pixels
// No need to draw anything if the labels are turned off with an opacity
// setting near 0.
if (ms_globalOpacity <= 0.01f)
{
return;
}
// Render during the opaque pass if opaque or during the translucent pass if not.
if (rc.pass() == RenderContext::TranslucentPass)
{
// Get the position of the camera in the body-fixed frame of the labeled object
Transform3f inv = Transform3f(rc.modelview().inverse(Affine)); // Assuming an affine modelview matrix
Vector3f cameraPosition = inv.translation();
float overallPixelSize = boundingSphereRadius() / (rc.pixelSize() * cameraPosition.norm());
// Only draw individual labels if the overall projected size of the set exceeds the threshold
if (overallPixelSize > visibleSizeThreshold)
{
// Labels are treated as either completely visible or completely occluded. A label is
// visible when the labeled point isn't blocked by the occluding ellipsoid.
AlignedEllipsoid testEllipsoid(m_occludingEllipsoid.semiAxes() * 0.999);
Vector3f ellipsoidSemiAxes = testEllipsoid.semiAxes().cast<float>();
Vector3f viewDir = -cameraPosition.normalized();
double distanceToEllipsoid = 0.0;
// Instead of computing the ellipsoid intersection (as the line below), just treat the planet as a sphere
//TestRayEllipsoidIntersection(cameraPosition, viewDir, ellipsoidSemiAxes, &distanceToEllipsoid);
distanceToEllipsoid = (cameraPosition.norm() - ellipsoidSemiAxes.maxCoeff()) * 0.99f;
// We don't want labels partially hidden by the planet ellipsoid, so we'll project them onto a
// plane that lies just in front of the planet ellipsoid and which is parallel to the view plane
Hyperplane<float, 3> labelPlane(viewDir, cameraPosition + viewDir * float(distanceToEllipsoid));
for (vector<Feature, Eigen::aligned_allocator<Feature> >::const_iterator iter = m_features.begin(); iter != m_features.end(); ++iter)
{
Vector3f r = iter->position - cameraPosition;
Vector3f labelPosition = labelPlane.projection(iter->position);
float k = -(labelPlane.normal().dot(cameraPosition) + labelPlane.offset()) / (labelPlane.normal().dot(r));
labelPosition = cameraPosition + k * r;
rc.pushModelView();
rc.translateModelView(labelPosition);
float featureDistance = rc.modelview().translation().norm();
float pixelSize = iter->size / (rc.pixelSize() * featureDistance);
float d = r.norm();
r /= d;
double t = 0.0;
TestRayEllipsoidIntersection(cameraPosition, r, ellipsoidSemiAxes, &t);
if (pixelSize > visibleSizeThreshold && d < t)
{
rc.drawEncodedText(Vector3f::Zero(), iter->label, m_font.ptr(), TextureFont::Utf8, iter->color, ms_globalOpacity);
}
rc.popModelView();
}
}
}
}
