protected void assembleVertexControlPoints(DrawContext dc) {
Terrain terrain = dc.getTerrain();
ExtrudedPolygon polygon = this.getPolygon();
Position refPos = polygon.getReferencePosition();
Vec4 refPoint = terrain.getSurfacePoint(refPos.getLatitude(), refPos.getLongitude(), 0);
int altitudeMode = polygon.getAltitudeMode();
double height = polygon.getHeight();
Vec4 vaa = null;
double vaaLength = 0; // used to compute independent length of each cap vertex
double vaLength = 0;
int i = 0;
for (LatLon location : polygon.getOuterBoundary()) {
Vec4 vert;
// Compute the top/cap point.
if (altitudeMode == WorldWind.CONSTANT || !(location instanceof Position)) {
if (vaa == null) {
// Compute the vector lengths of the top and bottom points at the reference position.
vaa = refPoint.multiply3(height / refPoint.getLength3());
vaaLength = vaa.getLength3();
vaLength = refPoint.getLength3();
}
// Compute the bottom point, which is on the terrain.
vert = terrain.getSurfacePoint(location.getLatitude(), location.getLongitude(), 0);
double delta = vaLength - vert.dot3(refPoint) / vaLength;
vert = vert.add3(vaa.multiply3(1d + delta / vaaLength));
} else if (altitudeMode == WorldWind.RELATIVE_TO_GROUND) {
vert =
terrain.getSurfacePoint(
location.getLatitude(),
location.getLongitude(),
((Position) location).getAltitude());
} else // WorldWind.ABSOLUTE
{
vert =
terrain
.getGlobe()
.computePointFromPosition(
location.getLatitude(),
location.getLongitude(),
((Position) location).getAltitude() * terrain.getVerticalExaggeration());
}
Position vertexPosition = this.wwd.getModel().getGlobe().computePositionFromPoint(vert);
this.controlPoints.add(
new ControlPointMarker(
MOVE_VERTEX_ACTION, vertexPosition, vert, this.vertexControlAttributes, i));
i++;
}
}
/**
* Compute points on either side of a line segment. This method requires a point on the line, and
* either a next point, previous point, or both.
*
* @param point Center point about which to compute side points.
* @param prev Previous point on the line. May be null if {@code next} is non-null.
* @param next Next point on the line. May be null if {@code prev} is non-null.
* @param leftPositions Left position will be added to this list.
* @param rightPositions Right position will be added to this list.
* @param halfWidth Distance from the center line to the left or right lines.
* @param globe Current globe.
*/
protected void generateParallelPoints(
Vec4 point,
Vec4 prev,
Vec4 next,
List<Position> leftPositions,
List<Position> rightPositions,
double halfWidth,
Globe globe) {
if ((point == null) || (prev == null && next == null)) {
String message = Logging.getMessage("nullValue.PointIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
if (leftPositions == null || rightPositions == null) {
String message = Logging.getMessage("nullValue.PositionListIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
if (globe == null) {
String message = Logging.getMessage("nullValue.GlobeIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
Vec4 offset;
Vec4 normal = globe.computeSurfaceNormalAtPoint(point);
// Compute vector in the direction backward along the line.
Vec4 backward = (prev != null) ? prev.subtract3(point) : point.subtract3(next);
// Compute a vector perpendicular to segment BC, and the globe normal vector.
Vec4 perpendicular = backward.cross3(normal);
double length;
// If both next and previous points are supplied then calculate the angle that bisects the angle
// current, next, prev.
if (next != null && prev != null && !Vec4.areColinear(prev, point, next)) {
// Compute vector in the forward direction.
Vec4 forward = next.subtract3(point);
// Calculate the vector that bisects angle ABC.
offset = forward.normalize3().add3(backward.normalize3());
offset = offset.normalize3();
// Compute the scalar triple product of the vector BC, the normal vector, and the offset
// vector to
// determine if the offset points to the left or the right of the control line.
double tripleProduct = perpendicular.dot3(offset);
if (tripleProduct < 0) {
offset = offset.multiply3(-1);
}
// Determine the length of the offset vector that will keep the left and right lines parallel
// to the control
// line.
Angle theta = backward.angleBetween3(offset);
if (!Angle.ZERO.equals(theta)) length = halfWidth / theta.sin();
else length = halfWidth;
} else {
offset = perpendicular.normalize3();
length = halfWidth;
}
offset = offset.multiply3(length);
// Determine the left and right points by applying the offset.
Vec4 ptRight = point.add3(offset);
Vec4 ptLeft = point.subtract3(offset);
// Convert cartesian points to geographic.
Position posLeft = globe.computePositionFromPoint(ptLeft);
Position posRight = globe.computePositionFromPoint(ptRight);
leftPositions.add(posLeft);
rightPositions.add(posRight);
}
