Contributor: SCOTT EARNEST program Chaos; {Triangular fractal generator Based on program "Chaos" published in Nibble, June 1989 (Vol. 10, No. 6) One-Liner winner written by Max Raymond of Huston, TX. Program inspired by a PBS broadcast of Nova, called "Chaos". Adapted for Turbo Pascal by Scott Earnest, 1994. scott@whiplash.pc.cc.cmu.edu About the program: When the program is run, it will ask for 4 sets of coordinates. The first three are the vertices of the triangle, and the fourth is the location of the "traveler", the point that moves around the screen leaving its path. The traveler may start at any position either inside or outside the tri- angle. Press any key to exit the program. The original author's comment about the program: "A three-sided die is simulated, and its roll corresponds to one of the three vertices of the triangle. The traveler will move halfway from its current point toward the vertex selected by the die roll. A copy of the traveler is left behind at its old position, while the traveler is redrawn at its new position. The process is then repeated. The pattern that emerges is a record of the traveler's journey, as it jumps from point to point." } uses graph, crt; const BGIPath : string[80] = 'E:\BP\BGI'; type TPoint = record x, y : integer; end; var grDriver, grMode, grError : integer; MaxX, MaxY : word; TriExt : array [1 .. 4] of TPoint; procedure StartGraph; begin grDriver := Detect; initgraph (grDriver, grMode, BGIPath); grError := GraphResult; if grError <> grOk then begin writeln ('Graphics error: ', GraphErrorMsg(grError)); halt (1); end; MaxX := getmaxx; MaxY := getmaxy; end; procedure InputPoints; var pnum : byte; tx, ty : word; function inputnum (idx : byte; max : word; ch : char) : word; var inval, err : word; instr : string; begin repeat if idx < 4 then write ('Enter ',ch,' vertex #',idx,': ') else write ('Enter "traveler" start ',ch,': '); readln (instr); val (instr, inval, err); if (err > 0) or (inval > max) then writeln ('Invalid entry. Please re-enter.'); until (inval <= Max); inputnum := inval; end; begin writeln ('Screen range = X:(0-',MaxX,'); Y:(0-',MaxY,').'); for pnum := 1 to 4 do begin TriExt[pnum].x := inputnum (pnum, MaxX, 'X'); TriExt[pnum].y := inputnum (pnum, MaxY, 'Y'); end; end; procedure DrawChaos; var select : byte; begin while keypressed do readkey; repeat select := random(3) + 1; TriExt[4].x := TriExt[4].x + (TriExt[select].x - TriExt[4].x) div 2; TriExt[4].y := TriExt[4].y + (TriExt[select].y - TriExt[4].y) div 2; putpixel (TriExt[4].x, TriExt[4].y, 15); until keypressed; while keypressed do readkey; end; begin Randomize; StartGraph; RestoreCRTMode; clrscr; InputPoints; SetGraphMode (GetGraphMode); DrawChaos; CloseGraph; RestoreCRTMode; clrscr; end.