Optimize intersection computation for envelopes

[mbasmanova]

I cannot find a method to compute intersection of two envelopes. The only way I know to do that is via OGCGeometry:

OGCGeometry.createFromEsriGeometry(a, null).intersection(OGCGeometry.createFromEsriGeometry(b, null))

However this method is very slow. It is about 300 times slower than envelope-specific computation: prestodb/presto#10327

    @Nullable
    public static Envelope intersection(Envelope envelope, Envelope otherEnvelope)
    {
        requireNonNull(envelope, "envelope is null");
        requireNonNull(otherEnvelope, "otherEnvelope is null");

        if (envelope.getXMax() < otherEnvelope.getXMin()
                || envelope.getXMin() > otherEnvelope.getXMax()
                || envelope.getYMax() < otherEnvelope.getYMin()
                || envelope.getYMin() > otherEnvelope.getYMax()) {
            return null;
        }

        return new Envelope(
                max(envelope.getXMin(), otherEnvelope.getXMin()),
                max(envelope.getYMin(), otherEnvelope.getYMin()),
                min(envelope.getXMax(), otherEnvelope.getXMax()),
                min(envelope.getYMax(), otherEnvelope.getYMax()));
    }

Would it be possible to add an efficient Envelope#intersection API?

[stolstov]

@mbasmanova See Envelope.intersect(Envelope) and Envelope2D.intersect(Envelope2D).

[mbasmanova]

@stolstov Sergey, these return a boolean and not the intersection geometry (envelope) itself.

[stolstov]

@mbasmanova These methods change e1 polygon as in e1.intersect(e2). The result polygon will be empty if they dont intersect and as well the method returns boolean as extra bonus.

[mbasmanova]

@stolstov Sergey, thanks for explaining. Let me try that.

[mbasmanova]

@stolstov Sergey, it works, except for one case when this is not empty and the other is empty. In that case it returns false, but this is unchanged.

public boolean intersect(Envelope2D other) {
		if (isEmpty() || other.isEmpty())
			return false;

I think the above needs to be changed to:

public boolean intersect(Envelope2D other) {
		if (isEmpty() || other.isEmpty()) {
                         setEmpty();
			return false;
		}

[stolstov]

Yes, that's a bug.

[alocke]

Verification: TestEnvelope.testIntersect()