Frustum QGeoCameraTilesPrivate::frustum(double fieldOfViewGradient) const
{
QDoubleVector3D center = sideLength_ * QGeoProjection::coordToMercator(camera_.center());
center.setZ(0.0);
double f = qMin(screenSize_.width(), screenSize_.height()) / (1.0 * tileSize_);
double z = std::pow(2.0, camera_.zoomLevel() - intZoomLevel_);
double altitude = f / (2.0 * z);
QDoubleVector3D eye = center;
eye.setZ(altitude);
QDoubleVector3D view = eye - center;
QDoubleVector3D side = QDoubleVector3D::normal(view, QDoubleVector3D(0.0, 1.0, 0.0));
QDoubleVector3D up = QDoubleVector3D::normal(side, view);
double nearPlane = sideLength_ / (1.0 * tileSize_ * (1 << maxZoom_));
double farPlane = 3.0;
double aspectRatio = 1.0 * screenSize_.width() / screenSize_.height();
double hn = 0.0;
double wn = 0.0;
double hf = 0.0;
double wf = 0.0;
// fixes field of view at 45 degrees
// this assumes that viewSize = 2*nearPlane x 2*nearPlane
if (aspectRatio > 1.0) {
hn = 2 * fieldOfViewGradient * nearPlane;
wn = hn * aspectRatio;
hf = 2 * fieldOfViewGradient * farPlane;
wf = hf * aspectRatio;
} else {
wn = 2 * fieldOfViewGradient * nearPlane;
hn = wn / aspectRatio;
wf = 2 * fieldOfViewGradient * farPlane;
hf = wf / aspectRatio;
}
QDoubleVector3D d = center - eye;
d.normalize();
up.normalize();
QDoubleVector3D right = QDoubleVector3D::normal(d, up);
QDoubleVector3D cf = eye + d * farPlane;
QDoubleVector3D cn = eye + d * nearPlane;
Frustum frustum;
frustum.topLeftFar = cf + (up * hf / 2) - (right * wf / 2);
frustum.topRightFar = cf + (up * hf / 2) + (right * wf / 2);
frustum.bottomLeftFar = cf - (up * hf / 2) - (right * wf / 2);
frustum.bottomRightFar = cf - (up * hf / 2) + (right * wf / 2);
frustum.topLeftNear = cn + (up * hn / 2) - (right * wn / 2);
frustum.topRightNear = cn + (up * hn / 2) + (right * wn / 2);
frustum.bottomLeftNear = cn - (up * hn / 2) - (right * wn / 2);
frustum.bottomRightNear = cn - (up * hn / 2) + (right * wn / 2);
return frustum;
}
