Visualization problems with center to center connections.

[Skybuck Flying]

I am trying to draw/render lines from cell center to cell center... See picture below...

In case you wanna see crazy video, check here:

https://www.youtube.com/live/-EsixpO9mBk?feature=share

Anyway it would be great if this library had some support to do things like this more easily...

I am currently use code from c++ geodesy
https://github.com/sslnjz/geodesy
Converted to Delphi and such... and my own function ClosestPointDistanceToClosestPointOnSegment below to try and accomplish this, but all of this math seems to collapse under certain conditions, not sure if that is truely happening but seems so... or very maybe uber returning some weird data, or some computation is failing:

Plus some x,y,z to lat, long conversion code...

// engineer who provided it to you for assistance.
// Define some earth constants
const MAJA = (6378137.0); // semi major axis of ref ellipsoid
const FLAT = (1.0/298.2572235630); // flattening coef of ref ellipsoid.
// These are derived values from the above WGS-84 values
const ESQR = (FLAT * (2.0-FLAT)); // 1st eccentricity squared
const OMES = (1.0 - ESQR); // 1 minus eccentricity squared
const EFOR = (ESQR * ESQR); // Sqr of the 1st eccentricity squared
const ASQR = (MAJA * MAJA); // semi major axis squared := nlmaja**

procedure ConvertECEFToLTP
(
const ParaEcef : TEcef;
var ParaLtp : TLtp
);
var
a0,a1,a2,a3,a4,b0,b1,b2,b3 : double;
b,c0,opqk,qk,qkc,qks,f,fprm : double;
k : integer;
ytemp, xtemp : double;
begin
// Convert from ParaEcef (XYZ) to LTP (ParaLtp.Lat/ParaLtp.Lon/ParaLtp.Alt)

//-------------------------------------------
// b := (00 + 11) / semi_major_axis_squared
// c := (z*z) / semi_major_axis_squared
//-------------------------------------------
b :=
(
(ParaEcef.x * ParaEcef.x) +
(ParaEcef.y * ParaEcef.y)
) / ASQR;
c0 :=
(ParaEcef.z * ParaEcef.z) / ASQR;

//-------------------------------------------
// a0 := c * one_minus_eccentricity_sqr
// a1 := 2 * a0
// a2 := a0 + b - first_eccentricity_to_fourth
// a3 := -2.0 * first_eccentricity_to_fourth
// a4 := - first_eccentricity_to_fourth
//-------------------------------------------
a0 := OMES * c0;
a1 := 2.0 * a0;
a2 := a0 + b - EFOR;
a3 := -2.0 * EFOR;
a4 := - EFOR;

//-------------------------------------------
// b0 := 4 * a0, b1 := 3 * a1
// b2 := 2 * a2, b3 := a3
//-------------------------------------------
b0 := 4.0 * a0;
b1 := 3.0 * a1;
b2 := 2.0 * a2;
b3 := a3;

//-------------------------------------------
// Compute First Eccentricity Squared
//-------------------------------------------
qk := ESQR;

// for (k := 1; k <:= 3; k++)
for k := 1 to 3 do
begin
qks := qk * qk;
qkc := qk * qks;
f :=
(a0 * qks * qks) +
(a1 * qkc) +
(a2 * qks) +
(a3 * qk) + a4;
fprm :=
(b0 * qkc) +
(b1 * qks) +
(b2 * qk) + b3;
qk := qk - (f / fprm);
end;

//-------------------------------------------
// Compute latitude, longitude, altitude
//-------------------------------------------
opqk := 1.0 + qk;
if
(
(ParaEcef.x = 0.0) and
(ParaEcef.y = 0.0)
) then
// on the earth's axis
begin
// We are sitting EXACTLY on the earth's axis
// Probably at the center or on or near one of the poles
ParaLtp.Lon := 0.0; // as good as any other value
if (ParaEcef.z >= 0.0) then
begin
ParaLtp.Lat := PI / 2; // ParaLtp.Alt above north pole
end else
begin
ParaLtp.Lat := -PI / 2; // ParaLtp.Alt above south pole
end;
end else
begin
ytemp := opqk * ParaEcef.z;
xtemp := sqrt
(
( ParaEcef.x * ParaEcef.x ) +
( ParaEcef.y * ParaEcef.y )
);
ParaLtp.Lat := arctan2( ytemp, xtemp );
ParaLtp.Lon := arctan2( ParaEcef.y, ParaEcef.x );
end;
ParaLtp.Alt :=
(
1.0 - OMES / ESQR * qk
) * MAJA *
sqrt
(
(
b / (opqk * opqk)
) + c0
);

end; // ConvertECEFToLTP()

// written by Skybuck Flying ! ;) :) =D
function ClosestPointDistanceToClosestPointOnSegment
(
ParaPointX, ParaPointY, ParaPointZ : double;
ParaStartX, ParaStartY, ParaStartZ : double;
ParaEndX, ParaEndY, ParaEndZ : double;
ParaRadius : double {= 6371e3} // (Mean) radius of earth (defaults to radius in metres).
) : double;
var
vPoint,
vSegmentPoint1,
vSegmentPoint2,
vClosestPointOnSegment : TLatLonNvectorSpherical;
begin
vSegmentPoint1.FromXYZ2( ParaStartX, ParaStartY, ParaStartZ, ParaRadius );
vSegmentPoint2.FromXYZ2( ParaEndX, ParaEndY, ParaEndZ, ParaRadius );
vPoint.FromXYZ2( ParaPointX, ParaPointY, ParaPointZ, ParaRadius );

vClosestPointOnSegment := nearestPointOnSegment
(
vPoint,
vSegmentPoint1,
vSegmentPoint2,
ParaRadius
);

result := distanceTo
(
vPoint, vClosestPointOnSegment, ParaRadius
);

end;

function ClosestPointDistanceToClosestPointOnSegmentV2
(
ParaPointX, ParaPointY, ParaPointZ : double;
ParaStartX, ParaStartY, ParaStartZ : double;
ParaEndX, ParaEndY, ParaEndZ : double;
ParaRadius : double {= 6371e3} // (Mean) radius of earth (defaults to radius in metres).
) : double;
var
vPoint,
vSegmentPoint1,
vSegmentPoint2,
vClosestPointOnSegment : TLatLonNvectorSpherical;
vEcef : Tecef;
vLtp : Tltp;
begin
// convert start x,y,z to lat lng
vEcef.X := ParaStartX;
vEcef.Y := ParaStartY;
vEcef.Z := ParaStartZ;

ConvertECEFToLTP
(
vEcef,
vLtp
);

vSegmentPoint1.mLat := vLtp.Lat;
vSegmentPoint1.mLon := vLtp.Lon;

// convert end x,y,z to lat lang
vEcef.X := ParaEndX;
vEcef.Y := ParaEndY;
vEcef.Z := ParaEndZ;

ConvertECEFToLTP
(
vEcef,
vLtp
);

vSegmentPoint2.mLat := vLtp.Lat;
vSegmentPoint2.mLon := vLtp.Lon;

// ParaRadius ??

// convert point x,y,z to lat lng
vEcef.X := ParaPointX;
vEcef.Y := ParaPointY;
vEcef.Z := ParaPointZ;

ConvertECEFToLTP
(
vEcef,
vLtp
);

vPoint.mLat := vLtp.Lat;
vPoint.mLon := vLtp.Lon;

vClosestPointOnSegment := nearestPointOnSegment
(
vPoint,
vSegmentPoint1,
vSegmentPoint2,
ParaRadius
);

result := distanceTo
(
vPoint, vClosestPointOnSegment, ParaRadius
);

end;

Any idea what could be wrong ? If you need more code let me know...

[Isaac Brodsky]

As I understand this issue is about your rendering code -- I don't think this is the place to get help on that.