var X1, X2, X3, X4, Y1, Y2, Y3, Y4;
X1 = argument0;
Y1 = argument1;
X2 = argument2;
Y2 = argument3;
X3 = argument4;
Y3 = argument5;
X4 = argument6;
Y4 = argument7;
X2 -= X1;
Y2 -= Y1;
X3 -= X1;
Y3 -= Y1;
X4 -= X1;
Y4 -= Y1;
X1 = 0;
Y1 = 0;
Y1 = 1/(X2*X2+Y2*Y2);
X1 = X3;
X3 = (X3*X2+Y3*Y2)*Y1;
Y3 = (Y3*X2-X1*Y2)*Y1;
X1 = X4;
X4 = (X4*X2+Y4*Y2)*Y1;
Y4 = (Y4*X2-X1*Y2)*Y1;
if (Y3 == Y4)
  exit;
Y1 = power((X4-X3)*(X4-X3)+(Y4-Y3)*(Y4-Y3), -.5); //1/sqrt()
Y3 *= Y1;
Y4 *= Y1;
X1 = -Y3/(Y4-Y3);
Y1 = X3+(X4-X3)*X1;
if (X1 >= 0 && Y1 >= 0 && X1 <= 1 && Y1 <= 1)
  draw_circle_color(argument0+(argument2-argument0)*Y1, argument1+(argument3-argument1)*Y1, 3, c_red, c_red, 0);