XProfan

Function Lines_Intersect(ax#, ay#, bx#, by#, cx#, cy#, dx#, dy#)
rn# = (ay#-cy#)*(dx#-cx#) - (ax#-cx#)*(dy#-cy#)
rd# = (bx#-ax#)*(dy#-cy#) - (by#-ay#)*(dx#-cx#)

If rd# = 0

    Return False

Else

    sn# = (ay#-cy#)*(bx#-ax#) - (ax#-cx#)*(by#-ay#)
    intersection_ab# = rn# / rd#
    intersection_cd# = sn# / rd#
    intersection_x#  = ax# + intersection_ab#*(bx#-ax#)
    intersection_y#  = ay# + intersection_ab#*(by#-ay#)
    Return True

EndIf

End Function

If intersection=0 Or intersection_ab#<0 Or intersection_ab#>1 Or intersection_cd#<0 Or intersection_cd#>1 Then

    Text 0,40,"Linien kreuzen nicht"

Else

    Text 0,40,"Linien kreuzen"

EndIf

float intersection_ab,intersection_cd,intersection_x,intersection_y

proc LineIntersec(float ax,ay,bx,by,cx,cy,dx,dy)

    float rn:=(ay-cy)*(dx-cx) - (ax-cx)*(dy-cy)
    float rd:=(bx-ax)*(dy-cy) - (by-ay)*(dx-cx)
    case (rd==0) : return false
    float sn = (ay-cy)*(bx-ax) - (ax-cx)*(by-ay)
    intersection_ab = rn / rd
    intersection_cd = sn / rd
    intersection_x  = ax + intersection_ab*(bx-ax)
    intersection_y  = ay + intersection_ab*(by-ay)
    return true

 {$cleq}
const myPI=3.1415926535897932384626433832795
float cos_outpx,cos_outpy,w
float intersection_ab,intersection_cd,intersection_x,intersection_y
bool intersection
cls

while 1

    cls
    w:=wnk(100,100,mousex,mousey,false)
    print int(w),"°  "
    getcircp 100,100,50,w+90
    drawtext cos_outpx,cos_outpy,"+"
    line 150,50 - 150,200
    intersection:=LineIntersec(100,100,mousex,mousey,150,50,150,200)

    If (intersection==false) Or (intersection_ab<0) Or (intersection_ab>1) Or (intersection_cd<0) Or (intersection_cd>1)

        print "Linien kreuzen nicht"

    Else

        print "Linien kreuzen"

    EndIf

    sleep 50

wend

waitkey

proc LineIntersec(float ax,ay,bx,by,cx,cy,dx,dy)

    float rn:=(ay-cy)*(dx-cx) - (ax-cx)*(dy-cy)
    float rd:=(bx-ax)*(dy-cy) - (by-ay)*(dx-cx)
    case (rd==0) : return false
    float sn = (ay-cy)*(bx-ax) - (ax-cx)*(by-ay)
    intersection_ab = rn / rd
    intersection_cd = sn / rd
    intersection_x  = ax + intersection_ab*(bx-ax)
    intersection_y  = ay + intersection_ab*(by-ay)
    return true

endproc

proc wnk(float x1,y1,x2,y2,int mode)

    float dx=x2!-x1!
    float dy=y2!-y1!
    line x1,y1 - x2,y2
    case (dx<0) and (dy<0) : return wnk(x2,y2,x1,y1,3)
    case dx<0 : return wnk(x2,y1,x1,y2,1)
    case dy<0 : return wnk(x1,y2,x2,y1,2)
    casenot dx : dx=0.0000001
    casenot dy : dy=0.0000001
    float w=arctan(dy/dx)*57.295779513082320876798154814105

    if (mode==1)

        w:=90+(90-w)

    elseif (mode==2)

        w:=360-w

    elseif (mode==3)

        w:=180+w

    endif

    return w

endproc

proc getcircp(float xp,yp,r,w)

    cos_outpx:=((((r*sin(((-1*(((-1+w)*myPI)+myPI))/180))))*-1)+xp)
    cos_outpy:=((((r*cos(((-1*(((-1+w)*myPI)+myPI))/180))))*-1)+yp)
ENDPROC

proc LineIntersec(float ax,ay,bx,by,cx,cy,dx,dy)

    float rn:=(ay-cy)*(dx-cx) - (ax-cx)*(dy-cy)
    float rd:=(bx-ax)*(dy-cy) - (by-ay)*(dx-cx)
    case (rd==0) : return false
    float sn = (ay-cy)*(bx-ax) - (ax-cx)*(by-ay)
    float intersection_ab = rn / rd
    float intersection_cd = sn / rd
    float intersection_x  = ax + intersection_ab*(bx-ax)
    float intersection_y  = ay + intersection_ab*(by-ay)
    case (intersection_ab<0) Or (intersection_ab>1) Or (intersection_cd<0) Or (intersection_cd>1) : return false
    return true