SRL Archive - OSR Help

im trying to make a function the returns a random point in a triangle.

what i have the script dong is taking a random y value-between the lowest and highest y values- then trying to find the minimum and maximum possible x values for that y.

i need to find the two points i circled in red

anyone know how to help? deleteing this post

Make a rectangle by making a triangle on either side of the legs (hypotenuse of both new triangles on a leg of the original triangle) and search for the points in the rectangle and then exclude any points in the new triangles.

Or use inequalities. I think you could make that work.

but how do i find whether the points are in the triangles.

EDIT: your idea is good, better than mine. i think it would use less code if instead of testing those 3 extra triangles, i just tested whether the point is in the main triangle.

Edit2: inequalities is good. ill use that. ill post my finished point sorting code in a min.

function RandomPointInTriangle(p1,p2,p3:tpoint):tpoint;
var x1,x2,x3,y1,y2,y3:integer;
begin
  //sort points from top left to bottom right.
  //First find topleftmost point
  if min(p1.x,min(p2.x,p3.x)) = p1.x then
  begin
    if p1.x = p2.x then
    begin
      if min(p1.y,p2.y) = p1.y then
      begin
        x1 := p1.x;
        y1 := p1.y;
      end else
      begin
        x1 := p2.x;
        y1 := p2.y;
      end;
    end else if p1.x = p3.x then
    begin
      if min(p1.y,p3.y) = p1.y then
      begin
        x1 := p1.x;
        y1 := p1.y;
      end else
      begin
        x1 := p3.x;
        y1 := p3.y;
      end;
    end;
    //now find bottomrightmost point
    if p1.x = p2.x then
    begin
      if max(p1.y,p2.y) = p1.y then
      begin
        x3 := p1.x;
        y3 := p1.y;
      end else
      begin
        x3 := p2.x;
        y3 := p2.y;
      end;
    end else if p1.x = p3.x then
    begin
      if max(p1.y,p3.y) = p1.y then
      begin
        x3 := p1.x;
        y3 := p1.y;
      end else
      begin
        x3 := p3.x;
        y3 := p3.y;
      end;
    end;
    //now find the point we havnt used yet
    if x1 = p1.x and y1 = p1.y then
    begin
      if x3 = p2.x and y3 = p2.y then
      begin
        x2 := p3.x;
        y2 := p3.y;
      end;

      if x3 = p3.x and y3 = p3.y then
      begin
        x2 := p2.x;
        y2 := p2.y;
      end;
    end;

    if x1 = p2.x and y1 = p2.y then
    begin
      if x3 = p1.x and y3 = p1.y then
      begin
        x2 := p3.x;
        y2 := p3.y;
      end;

      if x3 = p3.x and y3 = p3.y then
      begin
        x2 := p1.x;
        y2 := p1.y;
      end;
    end;

    if x1 = p3.x and y1 = p3.y then
    begin
      if x3 = p1.x and y3 = p1.y then
      begin
        x2 := p2.x;
        y2 := p2.y;
      end;

      if x3 = p2.x and y3 = p2.y then
      begin
        x2 := p1.x;
        y2 := p1.y;
      end;
    end;
  end;
  writeln(x1)
  writeln(y1)
  writeln(x2)
  writeln(y2)
  writeln(x3)
  writeln(y3)
{
  //set x and y values
  x1 := p1.x;
  y1 := p1.y;
  x2 := p2.x;
  y2 := p2.y;
  x3 := p3.x;
  y3 := p3.y;
}
end;

result:

[Error] (57:32): Type mismatch at line 56
Compiling failed.

What's line 56?

if x1 = p1.x and y1 = p1.y then

Change x1-3 and y1-3 to Extended maybe?

i cant because it is a coordinate.

What do you need to do for it to compile, do you need to convert a variable to another type or something?

thats what im trying to fugre out

when i added the peice that gets the not min and not max coordinate. the last peice.

EDIT: i got it. when i used and, it was conecting the integer instead of the equations. i added parenthesis and now it works =D

From: g0tp0t
i cant because it is a coordinate.

deal with extendeds until you have the point, then at the end of the function, do ceil() or floor(), then use whatever function turns a float to an integer

now that it works, it doesnt work perfectly. somewhere this code is missing a possible scenario. if i do this:

function RandomPointInTriangle(p1,p2,p3:tpoint):tpoint;
var x1,x2,x3,y1,y2,y3:integer;
begin
  //sort points from top left to bottom right.
  //First find topleftmost point
  if min(p1.x,min(p2.x,p3.x)) = p1.x then
  begin
    if p1.x = p2.x then
    begin
      if min(p1.y,p2.y) = p1.y then
      begin
        x1 := p1.x;
        y1 := p1.y;
      end else
      begin
        x1 := p2.x;
        y1 := p2.y;
      end;
    end else if p1.x = p3.x then
    begin
      if min(p1.y,p3.y) = p1.y then
      begin
        x1 := p1.x;
        y1 := p1.y;
      end else
      begin
        x1 := p3.x;
        y1 := p3.y;
      end;
    end;
    //now find bottomrightmost point
    if p1.x = p2.x then
    begin
      if max(p1.y,p2.y) = p1.y then
      begin
        x3 := p1.x;
        y3 := p1.y;
      end else
      begin
        x3 := p2.x;
        y3 := p2.y;
      end;
    end else if p1.x = p3.x then
    begin
      if max(p1.y,p3.y) = p1.y then
      begin
        x3 := p1.x;
        y3 := p1.y;
      end else
      begin
        x3 := p3.x;
        y3 := p3.y;
      end;
    end;
    //now find the point we havnt used yet
    if (x1 = p1.x) and (y1 = p1.y) then
    begin
      if (x3 = p2.x) and (y3 = p2.y )then
      begin
        x2 := p3.x;
        y2 := p3.y;
      end;

      if (x3 = p3.x) and (y3 = p3.y) then
      begin
         if (x1 = p1.x) and (y1 = p1.y) then
         begin
           x2 := p2.x;
           y2 := p2.y;
         end;
      end;
    end;

    if (x1 = p2.x) and (y1 = p2.y) then
    begin
      if (x3 = p1.x) and (y3 = p1.y) then
      begin
        x2 := p3.x;
        y2 := p3.y;
      end;

      if (x3 = p3.x) and (y3 = p3.y) then
      begin
        x2 := p1.x;
        y2 := p1.y;
      end;
    end;

    if (x1 = p3.x) and (y1 = p3.y) then
    begin
      if (x3 = p1.x) and (y3 = p1.y) then
      begin
        x2 := p2.x;
        y2 := p2.y;
      end;

      if (x3 = p2.x) and (y3 = p2.y) then
      begin
        x2 := p1.x;
        y2 := p1.y;
      end;
    end;  {}
  end;
  writeln(x1)
  writeln(y1)
  writeln(x2)
  writeln(y2)
  writeln(x3)
  writeln(y3)
{
  //set x and y values
  x1 := p1.x;
  y1 := p1.y;
  x2 := p2.x;
  y2 := p2.y;
  x3 := p3.x;
  y3 := p3.y;
}
end;
begin
RandomPointInTriangle(point(2,2),point(1,1),point(1,3));
end.

, then it prints out all the values as 0

MOAR DEBUGGING. a

ok, i think i figured it out. =\

i dont have any scenarios for when the first point isnt put in first. lol

ok, this way is realy complicated. anyone know of an easier way to sort the points

You ask very vague shit, which will make everyone look through your horrible code to even understand what you're asking, and at that point they've invested so much time into looking through the script they'll realize that it's a waste even trying to help.

How about you ask general questions which don't relate to your code, so we can help you with the general concept which you can code yourself.

im getting an out of range error, i dont know what it means though

function OrganiseTriPoints(p1,p2,p3:tpoint):TPointArray;
var x1,x2,x3,y1,y2,y3,pt1,pt2,pt3,yrange:integer;
begin
  yrange := max(p1.y,max(p2.y,p3.y))-min(p1.y,min(p2.y,p3.y));
  pt1 := p1.x*yrange+p1.y;
  pt2 := p2.x*yrange+p2.y;
  pt3 := p3.x*yrange+p3.y;
  //check for the upperleftmost point
  if min(pt1,min(pt2,pt3)) = pt1 then
  begin
    x1 := p1.x;
    y1 := p1.y;
  end;

  if min(pt1,min(pt2,pt3)) = pt2 then
  begin
    x1 := p2.x;
    y1 := p2.y;
  end;

  if min(pt1,min(pt2,pt3)) = pt3 then
  begin
    x1 := p3.x;
    y1 := p3.y;
  end;
  //check for the bottomrightmost point
  if max(pt1,max(pt2,pt3)) = pt1 then
  begin
    x3 := p1.x;
    y3 := p1.y;
  end;

  if max(pt1,max(pt2,pt3)) = pt2 then
  begin
    x3 := p2.x;
    y3 := p2.y;
  end;

  if max(pt1,max(pt2,pt3)) = pt3 then
  begin
    x3 := p3.x;
    y3 := p3.y;
  end;
  //find the middlemost point
  if ((pt1 < pt2) and (pt1 > pt3)) or ((pt1 > pt2) and (pt1 < pt3)) then
  begin
    x2 := p2.x;
    y2 := p2.y;
  end;

  if ((pt2 < pt1) and (pt2 > pt3)) or ((pt2 > pt1) and (pt2 < pt3)) then
  begin
    x2 := p2.x;
    y2 := p2.y;
  end;

  if ((pt3 < pt2) and (pt3 > pt1)) or ((pt3 > pt2) and (pt3 < pt1)) then
  begin
    x2 := p3.x;
    y2 := p3.y;
  end;
  result := [point(x1,y1),point(x2,y2),point(x3,y3)]
end;

function getslope(p1,p2:tpoint; intercept : double):extended;
begin
  result := ( p2.y-p1.y)/(p2.x-p1.x);
  intercept := result * p1.x-p1.y;
end;

function IsInTri(p,p1,p2,p3:TPoint):boolean;
var tpa : TPointArray; c1,c2,c3:TPoint; slope1,slope2,int1,int2:extended;
begin
  result := false;
  tpa := OrganiseTriPoints(p1,p2,p3);
  c1 := tpa[1];
  c2 := tpa[2];
  c3 := tpa[3];
  slope1 := getslope(c1,c2,int1);
  slope2 := getslope(c2,c3,int2);
  if (p.y > (slope1 * p.x+int1)) then
    if (p.y < (slope2 * p.x+int2)) then
      result := true;
end;

begin
IsInTri(point(2,2),point(1,1),point(5,5),point(5,1))
end.

error:

Compiled succesfully in 47 ms.
Error: Out Of Range at line 79

something is wrong with my getslop function because when i had it print out the values of slope1 slope2 int1 and int 2, i got 1,0,0,and 0 respectively

c1 := tpa[1];
c2 := tpa[2];
c3 := tpa[3];

should be

c1 := tpa[0];
c2 := tpa[1];
c3 := tpa[2];

I believe.

intercept := result * (p1.x-p1.y);

should be

intercept := result * (p1.x-p1.y);

ty
lol, yup. i shoudl have mentioned that i got that. lol

my new problem is my getslope function. it is supposed to return the slope and y intercept but i get values way off

I showed the fix. You forgot that scripts will be ran as scripted. It will do the order of operations correctly even if you know it should be different.

i took a whole new aproach and its very simple. it isnt working though.

var
  points:TPointArray;
  np:TPoint;
function OrganiseTriPoints(p1,p2,p3:tpoint):TPointArray;
var x1,x2,x3,y1,y2,y3,pt1,pt2,pt3,yrange:integer;
begin
  yrange := max(p1.y,max(p2.y,p3.y))-min(p1.y,min(p2.y,p3.y));
  pt1 := p1.x*yrange+p1.y;
  pt2 := p2.x*yrange+p2.y;
  pt3 := p3.x*yrange+p3.y;
  //check for the upperleftmost point
  if min(pt1,min(pt2,pt3)) = pt1 then
  begin
    x1 := p1.x;
    y1 := p1.y;
  end;

  if min(pt1,min(pt2,pt3)) = pt2 then
  begin
    x1 := p2.x;
    y1 := p2.y;
  end;

  if min(pt1,min(pt2,pt3)) = pt3 then
  begin
    x1 := p3.x;
    y1 := p3.y;
  end;
  //check for the bottomrightmost point
  if max(pt1,max(pt2,pt3)) = pt1 then
  begin
    x3 := p1.x;
    y3 := p1.y;
  end;

  if max(pt1,max(pt2,pt3)) = pt2 then
  begin
    x3 := p2.x;
    y3 := p2.y;
  end;

  if max(pt1,max(pt2,pt3)) = pt3 then
  begin
    x3 := p3.x;
    y3 := p3.y;
  end;
  //find the middlemost point
  if ((pt1 < pt2) and (pt1 > pt3)) or ((pt1 > pt2) and (pt1 < pt3)) then
  begin
    x2 := p2.x;
    y2 := p2.y;
  end;

  if ((pt2 < pt1) and (pt2 > pt3)) or ((pt2 > pt1) and (pt2 < pt3)) then
  begin
    x2 := p2.x;
    y2 := p2.y;
  end;

  if ((pt3 < pt2) and (pt3 > pt1)) or ((pt3 > pt2) and (pt3 < pt1)) then
  begin
    x2 := p3.x;
    y2 := p3.y;
  end;
  result := [point(x1,y1),point(x2,y2),point(x3,y3)]
end;


function areatri(p1,p2,p3:TPoint):extended;     //gets the area of a triangle
var tpa:TPointArray;w,h:extended;
begin
  tpa := OrganiseTriPoints(p1,p2,p3);
  w := tpa[2].x-tpa[0].x;
  h := max(tpa[0].y,max(tpa[1].y,tpa[2].y))-min(tpa[0].y,min(tpa[1].y,tpa[2].y));
  result := w*h*0.5
end;

function IsInTri(p,p1,p2,p3:TPoint):boolean;
var sum:extended;
begin      //This will split the triangle into 3 smaller ones and get the total area.
           //If the area is more than the base triangle then point is outside.
sum := areatri(p,p1,p2)+areatri(p,p2,p3)+areatri(p,p3,p1);
result := (abs(sum - areatri(p1,p2,p3))<1);
end;
//main
begin
  points := [point(0,767),point(512,0),point(1023,767)]
  points := OrganiseTriPoints(points[0],points[1],points[2]);
  np := point(RandomRange(points[0].x,points[2].x),RandomRange(max(points[0].y,max(points[1].y,points[2].y))-min(points[0].y,min(points[1].y,points[2].y)),min(points[0].y,min(points[1].y,points[2].y))));
  writeln(np);
  writeln(IsInTri(np,points[0],points[1],points[2]));
end.

is that considered clean? i don't know how to use case statements in simba yet so dont count that.

case Random(3) of
  0: Writeln('Bob says hi.');
  1: Writeln('Margret says bye.');
  2..5: Writeln('See Spot run.');
  6, 9, 10: Writeln('Run, Spot, run.');
  7, 8: begin
          Writeln('Spot is tired.');
          Writeln('Spot is sleeping.');
        end;
end;

oh. thanks. do you or anyone else know what internal error 20 means? i haven't found anything wrong in the script.

EDIT: here is with the cases:

var
  points:TPointArray;
  np:TPoint;
function OrganiseTriPoints(p1,p2,p3:tpoint):TPointArray;
var x1,x2,x3,y1,y2,y3,pt1,pt2,pt3,yrange:integer;
begin
  yrange := max(p1.y,max(p2.y,p3.y))-min(p1.y,min(p2.y,p3.y));
  pt1 := p1.x*yrange+p1.y;
  pt2 := p2.x*yrange+p2.y;
  pt3 := p3.x*yrange+p3.y;
  //check for the upperleftmost point

  case min(pt1,min(pt2,pt3)) of
    pt1:
      begin
        x1 := p1.x;
        y1 := p1.y;
      end;
    pt2:
      begin
        x1 := p2.x;
        y1 := p2.y;
      end;
    pt3:
      begin
        x1 := p3.x;
        y1 := p3.y;
      end;
    end;
  //check for the bottomrightmost point
  case max(pt1,max(pt2,pt3)) of
    pt1:
      begin
        x3 := p1.x;
        y3 := p1.y;
      end;
    pt2:
      begin
        x3 := p2.x;
        y3 := p2.y;
      end;
    pt3:
      begin
        x3 := p3.x;
        y3 := p3.y;
      end;
    end;
  //find the middlemost point
  if ((pt1 < pt2) and (pt1 > pt3)) or ((pt1 > pt2) and (pt1 < pt3)) then
  begin
    x2 := p2.x;
    y2 := p2.y;
  end;

  if ((pt2 < pt1) and (pt2 > pt3)) or ((pt2 > pt1) and (pt2 < pt3)) then
  begin
    x2 := p2.x;
    y2 := p2.y;
  end;

  if ((pt3 < pt2) and (pt3 > pt1)) or ((pt3 > pt2) and (pt3 < pt1)) then
  begin
    x2 := p3.x;
    y2 := p3.y;
  end;
  result := [point(x1,y1),point(x2,y2),point(x3,y3)]
end;


function areatri(p1,p2,p3:TPoint):extended;     //gets the area of a triangle
var tpa:TPointArray;w,h:extended;               //gets the difference between leftmost and rightmost points
begin                                           //then it gets difference of min and max height.
  tpa := OrganiseTriPoints(p1,p2,p3);           //multiplies width and heith then divides that in half for area
  w := tpa[2].x-tpa[0].x;
  h := max(tpa[0].y,max(tpa[1].y,tpa[2].y))-min(tpa[0].y,min(tpa[1].y,tpa[2].y));
  result := w*h*0.5
end;

function IsInTri(p,p1,p2,p3:TPoint):boolean;
var sum:extended;
begin      //This will split the triangle into 3 smaller ones and sum the area of all three.
           //If the area is more than the base triangle then point is outside.
  sum := areatri(p,p1,p2)+areatri(p,p2,p3)+areatri(p,p3,p1);
  result := (abs(sum - areatri(p1,p2,p3))<1);
end;
           //main
begin
  points := [point(0,767),point(512,0),point(1023,767)]
  points := OrganiseTriPoints(points[0],points[1],points[2]);
  np := point(RandomRange(points[0].x,points[2].x),RandomRange(max(points[0].y,max(points[1].y,points[2].y))-min(points[0].y,min(points[1].y,points[2].y)),min(points[0].y,min(points[1].y,points[2].y))));
  writeln(np);
  writeln(IsInTri(np,points[0],points[1],points[2]));
end.

This thread is a little old, but heck. If you still need it, I think all you would have to do is generate aa and bb.

function RandomPointInTriangle (A, B,C :TPoint): TPoint 
var 
  aa, bb. cc: extended;
  rndX, rndY : integer;

  begin
    aa:= random number between 0.0 and 1.0 ; //after these two variables are figured out, it should work :)
    bb := random # between 0.0 and 1.0;
    if (aa + bb > 1.0) then
    begin
      a := 1 - a;
      b := 1 - b;
    end;
	
    c := 1 - a - b;
   	
    rndX := Round((aa*A.x)+(bb*B.x)+(cc*C.x));
    rndY := Round ((a*A.y)+(b*B.y)+(c*C.y));
   
    Result := Point(rndX, rndY);
end;

if people are still posting…get a load of this….

RandomPointInTriangle takes about a quater of a milisecond on a decent size triangle (at least 100 x 100 square)

function InRangeBetter(Value, Border1, Border2: Integer): Boolean;
begin
  Result := InRange(Value, Border1, Border2) or InRange(Value, Border2, Border1);
end;

function XToY(X: Integer; Point1, Point2: TPoint): Integer;
var
  M: Extended;
begin
  M := 1.0 * (Point2.y - Point1.y) / (Point2.x - Point1.x);
  Result := Round((X - Point1.x) * M) + Point1.y;
end;

function PointInTriangle(ThePoint: TPoint; TrianglePoint1, TrianglePoint2, TrianglePoint3: TPoint): Boolean;
var
  Error: Boolean;
begin
  if not InRange(ThePoint.x, Min(Min(TrianglePoint1.x, TrianglePoint2.x), TrianglePoint3.x), Max(Max(TrianglePoint1.x, TrianglePoint2.x), TrianglePoint3.x)) then
    Exit;
  if ((TrianglePoint1.x < ThePoint.x) and (TrianglePoint2.x < ThePoint.x)) or ((TrianglePoint1.x > ThePoint.x) and (TrianglePoint2.x > ThePoint.x)) then
    Result := InRangeBetter(ThePoint.y, XToY(ThePoint.x, TrianglePoint1, TrianglePoint3), XToY(ThePoint.x, TrianglePoint2, TrianglePoint3)) else
  if ((TrianglePoint1.x < ThePoint.x) and (TrianglePoint3.x < ThePoint.x)) or ((TrianglePoint1.x > ThePoint.x) and (TrianglePoint3.x > ThePoint.x)) then
    Result := InRangeBetter(ThePoint.y, XToY(ThePoint.x, TrianglePoint1, TrianglePoint2), XToY(ThePoint.x, TrianglePoint2, TrianglePoint3)) else
  if ((TrianglePoint2.x < ThePoint.x) and (TrianglePoint3.x < ThePoint.x)) or ((TrianglePoint2.x > ThePoint.x) and (TrianglePoint3.x > ThePoint.x)) then
    Result := InRangeBetter(ThePoint.y, XToY(ThePoint.x, TrianglePoint1, TrianglePoint2), XToY(ThePoint.x, TrianglePoint1, TrianglePoint3)) else
  if ThePoint.x = TrianglePoint1.x then
  begin
    if InRangeBetter(TrianglePoint1.x, TrianglePoint2.x, TrianglePoint3.x) then
      Result := InRangeBetter(ThePoint.y, TrianglePoint1.y, XToY(ThePoint.x, TrianglePoint2, TrianglePoint3)) else
      Result := ThePoint.y = TrianglePoint1.y;
  end else
  if ThePoint.x = TrianglePoint2.x then
  begin
    if InRangeBetter(TrianglePoint2.x, TrianglePoint1.x, TrianglePoint3.x) then
      Result := InRangeBetter(ThePoint.y, TrianglePoint2.y, XToY(ThePoint.x, TrianglePoint1, TrianglePoint3)) else
      Result := ThePoint.y = TrianglePoint1.y;
  end else
  if ThePoint.x = TrianglePoint3.x then
  begin
    if InRangeBetter(TrianglePoint3.x, TrianglePoint1.x, TrianglePoint2.x) then
      Result := InRangeBetter(ThePoint.y, TrianglePoint3.y, XToY(ThePoint.x, TrianglePoint1, TrianglePoint2)) else
      Result := ThePoint.y = TrianglePoint1.y;
  end;
end;     

function RandomPointInTriangle1(TrianglePoint1, TrianglePoint2, TrianglePoint3: TPoint): TPoint;
var
  Counter, X, Y: Integer;
  TPA: TPointArray;
begin
  for Counter := 1 to 100 do
  begin
    X := RandomRange(Min(Min(TrianglePoint1.x, TrianglePoint2.x), TrianglePoint3.x), Max(Max(TrianglePoint1.x, TrianglePoint2.x), TrianglePoint3.x) + 1);
    Y := RandomRange(Min(Min(TrianglePoint1.y, TrianglePoint2.y), TrianglePoint3.y), Max(Max(TrianglePoint1.y, TrianglePoint2.y), TrianglePoint3.y) + 1);
    if PointInTriangle(Point(X, Y), TrianglePoint1, TrianglePoint2, TrianglePoint3) then
    begin
      Result := Point(X, Y);
      Exit;
    end;
  end;
end;