DZone Snippets: graphic code

Langton's Ant in Python

scvalex (Alexandru Scvortov) — Fri, 15 Feb 2008 12:53:39 GMT

The following code simulates Langton's Ant using Python and PyGame.

A full explanation is given here.



#************************************************

# Rules of the game

#	1. If the ant is on a black square, it turns

#		right 90 and moves forward one unit

#	2. If the ant is on a white square, it turns

# 		left 90 and moves forward one unit

#	3. When the ant leaves a square, it inverts

#		colour

#

# SEE: http://mathworld.wolfram.com/LangtonsAnt.html

#************************************************



import sys, pygame

from pygame.locals import *

import time



dirs = (

		(-1, 0),

		(0, 1),

		(1, 0),

		(0, -1)

		)



cellSize = 12 # size in pixels of the board (4 pixels are used to draw the grid)

numCells = 64 # length of the side of the board

background = 0, 0, 0 # background colour; black here

foreground = 23, 23, 23 # foreground colour; the grid's colour; dark gray here

textcol = 177, 177, 177 # the colour of the step display in the upper left of the screen

antwalk = 44, 88, 44 # the ant's trail; greenish here

antant = 222, 44, 44 # the ant's colour; red here

fps = 1.0 / 40 # time between steps; 1.0 / 40 means 40 steps per second



def main():

	pygame.init()



	size = width, height = numCells * cellSize, numCells * cellSize



	pygame.display.set_caption("Langton's Ant")



	screen = pygame.display.set_mode(size) # Screen is now an object representing the window in which we paint

	screen.fill(background)

	pygame.display.flip() # IMPORTANT: No changes are displayed until this function gets called



	for i in xrange(1, numCells):

		pygame.draw.line(screen, foreground, (i * cellSize, 1), (i * cellSize, numCells * cellSize), 2)

		pygame.draw.line(screen, foreground, (1, i * cellSize), (numCells * cellSize, i * cellSize), 2)

	pygame.display.flip() # IMPORTANT: No changes are displayed until this function gets called



	font = pygame.font.Font(None, 36)



	antx, anty = numCells / 2, numCells / 2

	antdir = 0

	board = [[False] * numCells for e in xrange(numCells)]



	step = 1

	pause = False

	while True:

		for event in pygame.event.get():

				if event.type == QUIT:

					return

				elif event.type == KEYUP:

					if event.key == 32: # If space pressed, pause or unpause

						pause = not pause

					elif event.key == 115:

						pygame.image.save(screen, "Step%d.tga" % (step))



		if pause:

			time.sleep(fps)

			continue



		text = font.render("%d " % (step), True, textcol, background)

		screen.blit(text, (10, 10))

		

		if board[antx][anty]:

			board[antx][anty] = False # See rule 3

			screen.fill(background, pygame.Rect(antx * cellSize + 1, anty * cellSize + 1, cellSize - 2, cellSize - 2))

			antdir = (antdir + 1) % 4 # See rule 1

		else:

			board[antx][anty] = True # See rule 3

			screen.fill(antwalk, pygame.Rect(antx * cellSize + 1, anty * cellSize + 1, cellSize - 2, cellSize - 2))

			antdir = (antdir + 3) % 4 # See rule 2



		antx = (antx + dirs[antdir][0]) % numCells

		anty = (anty + dirs[antdir][1]) % numCells



		# The current square (i.e. the ant) is painted a different colour

		screen.fill(antant, pygame.Rect(antx * cellSize + 1, anty * cellSize + 1, cellSize -2, cellSize -2))



		pygame.display.flip() # IMPORTANT: No changes are displayed until this function gets called



		step += 1

		time.sleep(fps)



if __name__ == "__main__":

	main()

dynamic rails img headers

jm3 (john manoogian III) — Tue, 06 Nov 2007 00:52:30 GMT

// description of your code here



find views -name [a-z]\*rhtml | xargs -n1 grep -H "@page_title" | grep -v "<%" | sed "s/\@page_title = //" | sed "s/rhtml/png/" | sed "s:views/::" | sed "s:/:_:g" | sed "s:^:public/images/beta/headers/hdr_:" | sed "s/  //g"

Wave Plotter //Pascal Class

jonasraoni (Jonas Raoni Soares Silva) — Thu, 15 Jun 2006 19:28:29 GMT

A wave plotter component that is able to draw sin, poly and squared lines, I used this in a osciloscope xD

I didn't liked this code, but the draw part (TWaveShape.paint) is looking cool, I used the same "X" coord to draw the 3 kinds of lines :)

I mean:

loop(x){
case waveType of
wtSin: y := lala;
wtPoly: y := lele;
wtSqr: y := lili;
end;
}



unit WavePlotter;



interface



uses

  forms, dialogs, SysUtils, Classes, Controls, Graphics;



const

  PI2 = PI * 2;



type

  TWaveType = ( wtSqr, wtPoly, wtSin );



  TWave = class( TPersistent )

  public

    waveType: TWaveType;

    color: TColor;

    offset: integer;

    frequency, amplitude, volts, interval, gain: extended;



    procedure AssignTo(Dest: TPersistent); override;

  end;



  TWaveShape = class( TGraphicControl )

  protected

    fWaves: TList;

    fBoxSize: integer;

    fLineColor: TColor;



    function getWave(const index: integer): TWave;

    procedure setBoxSize(const Value: integer);



    function getBackgroundColor: TColor;

    procedure setBackgroundColor(const Value: TColor);

    procedure setLineColor(const Value: TColor);



  public

    constructor create( AOwner: TComponent ); override;

    destructor destroy; override;



    procedure clear;

    procedure delete( const index: integer );



    function add: integer;



    property waves[ const index: integer]: TWave read GetWave;



  published

    procedure paint; override;

    property boxSize: integer read fBoxSize write setBoxSize;

    property backgroundColor: TColor read getBackgroundColor write setBackgroundColor;

    property lineColor: TColor read fLineColor write setLineColor;



    //inherited

    //property Canvas;

    property Align;

    property Anchors;

    property Constraints;

    property DragCursor;

    property DragKind;

    property DragMode;

    property Enabled;

    //property Font;

    property ParentColor;

    //property ParentFont;

    property ParentShowHint;

    property PopupMenu;

    property ShowHint;

    property Visible;

    property OnClick;

    property OnContextPopup;

    property OnDblClick;

    property OnDragDrop;

    property OnDragOver;

    property OnEndDock;

    property OnEndDrag;

    property OnMouseDown;

    property OnMouseMove;

    property OnMouseUp;

    property OnStartDock;

    property OnStartDrag;

  end;



implementation



function max( const a, b: integer ): integer;

begin

  if a > b then

    result := a

  else

    result := b;

end;



{ TWaveShape }



function TWaveShape.add: integer;

begin

  result := fWaves.add( TWave.Create );

end;



procedure TWaveShape.clear;

begin

  while fWaves.count > 0 do begin

    TWave( fWaves[0] ).free;

    fWaves.delete( 0 );

  end;

end;



constructor TWaveShape.create(AOwner: TComponent);

begin

  inherited;

  fWaves := TList.create;

  fLineColor := clGray;

  color := clBtnFace;

  fBoxSize := 50;

end;



procedure TWaveShape.delete(const index: integer);

begin

  if ( index > -1 ) and ( index < fWaves.count ) then begin

    TWave( fWaves[index] ).free;

    fWaves.delete( index );

  end;

end;



destructor TWaveShape.destroy;

begin

  fWaves.free;

  inherited;

end;



function TWaveShape.getBackgroundColor: TColor;

begin

  result := color;

end;



function TWaveShape.getWave(const index: integer): TWave;

begin

  result := nil;

  if ( index > -1 ) and ( index < fWaves.count ) then

    result := TWave( fWaves[ index ] );

end;



procedure TWaveShape.paint;

var

  k, x: integer;

  lastX, lastY: array of integer;

  y: extended;

begin

  if not enabled then

    exit;

  canvas.brush.color := color;

  canvas.fillRect( clientRect );



  setLength( lastY, fWaves.count );

  setLength( lastX, fWaves.count );

  for k := 0 to high( lastY ) do begin

    lastY[k] := clientHeight div 2 + waves[k].offset;

    lastX[k] := 0;

  end;



  for x := 0 to max( clientWidth, clientHeight ) do begin

    with canvas do begin

      pen.color := fLineColor;

      pen.width := 1;

      pen.style := psDot;



      if x mod fBoxSize = 0 then begin

        moveTo( 0, x + trunc( frac( clientHeight / 2 / fBoxSize ) * fBoxSize ) );

        lineTo( clientWidth, x + trunc( frac( clientHeight / 2 / fBoxSize ) * fBoxSize ) );



        moveTo( x, 0 );

        lineTo( x, clientHeight );

      end;



      for k := 0 to fWaves.count - 1 do begin

        with waves[k] do begin

          pen.color := color;

          pen.width := 1;

          pen.style := psSolid;



          y := pi*k + PI2 * x * interval / fBoxSize * frequency;



          case waveType of

            wtSin:

              y := sin( y );

            wtPoly: begin

              y := frac( y / PI2 );

              if y <= 0.25 then

                y := y / 0.25

              else if y <= 0.75 then

                y := ( -y + 0.5 ) / 0.25

              else

                y := ( y - 1 ) / 0.25;

            end;

            wtSqr: begin

              if frac( y / PI2 ) <= 0.5 then

                y := 1

              else

                y := -1;

            end;

          end;

          y := ( y * ( fBoxSize / volts ) * amplitude * gain ) + clientHeight / 2 + offset;

          moveTo( lastX[k], lastY[k] );

          lastX[k] := x;

          lastY[k] := trunc( y );

          lineTo( x, lastY[k] );

        end;

      end;

    end;

  end;

end;



procedure TWaveShape.setBackgroundColor(const Value: TColor);

begin

  color := Value;

  Invalidate;

end;



procedure TWaveShape.setBoxSize(const Value: integer);

begin

  fBoxSize := Value;

  invalidate;

end;





procedure TWaveShape.setLineColor(const Value: TColor);

begin

  fLineColor := Value;

  Invalidate;

end;



{ TWave }



procedure TWave.AssignTo(Dest: TPersistent);

begin

  if Dest.ClassType <> TWave then

    inherited;

  with TWave( Dest ) do begin

    waveType := self.waveType;

    color := self.color;

    offset := self.offset;

    frequency := self.frequency;

    amplitude := self.amplitude;

    volts := self.volts;

    interval := self.interval;

    gain := self.gain;

  end;

end;



end.