ProgZoo Using and reusing stars

1. Vietnam

The flag of Vietnam has a yellow five pointed star on a red background. This star is a popular device on many flags, we define the star once and use it many times in later flags.

The given star has a radius of 100, it is centred on 0,0 which is the wrong place. We must translate to put it in the right place.

We use a slightly different method to draw shapes now. We construct a list of actions then execute them in one go.

Hint:

We can put a translation in place before drawing the star:

  dl.push_back(DrawableTranslation(100,100));

test text

2. Panama

The flag of Panama requires two stars. We can draw the same star twice.

test text

3. Bosnia and Herzegovina

static void drawFlag(Image& g){
  // Define the polygon star
  std::list<Coordinate> star;
  star.push_back(Coordinate(0,-25));
  star.push_back(Coordinate(6,-8));
  star.push_back(Coordinate(24,-8));
  star.push_back(Coordinate(9,3));
  star.push_back(Coordinate(15,20));
  star.push_back(Coordinate(0,9));
  star.push_back(Coordinate(-15,20));
  star.push_back(Coordinate(-9,3));
  star.push_back(Coordinate(-24,-8));
  star.push_back(Coordinate(-6,-8));

std::list<Coordinate> tri;
  tri.push_back(Coordinate(160,0));
  tri.push_back(Coordinate(464,0));
  tri.push_back(Coordinate(464,304));

// Build up a list of Drawable
  std::list<Magick::Drawable> dl;
  dl.push_back(DrawablePushGraphicContext());
  dl.push_back(DrawableFillColor("blue"));
  dl.push_back(DrawableRectangle(0,0,600,304));
  dl.push_back(DrawableFillColor("yellow"));
  dl.push_back(DrawablePolygon(tri));
  dl.push_back(DrawableTranslation(105,0));
  dl.push_back(DrawablePolygon(star));
  dl.push_back(DrawableTranslation(38,38));
  dl.push_back(DrawablePolygon(star));
  dl.push_back(DrawablePopGraphicContext());
  g.draw(dl);
}

The flag of Bosnia and Herzegovina includes 9 white stars. Each star is 38 right and 38 below the previous star.

test text

4. Democratic Republic of Congo (formerly Zaire)

static void drawFlag(Image& g){
  // Define the polygon star
  std::list<Coordinate> star;
  star.push_back(Coordinate(0,-100));
  star.push_back(Coordinate(22,-31));
  star.push_back(Coordinate(95,-31));
  star.push_back(Coordinate(36,12));
  star.push_back(Coordinate(59,81));
  star.push_back(Coordinate(0,38));
  star.push_back(Coordinate(-59,81));
  star.push_back(Coordinate(-36,12));
  star.push_back(Coordinate(-95,-31));
  star.push_back(Coordinate(-22,-31));

// Build up a list of Drawable
  std::list<Magick::Drawable> dl;
  dl.push_back(DrawablePushGraphicContext());
  dl.push_back(DrawableFillColor(
    ColorRGB(.69,.84,.9)));
  dl.push_back(DrawableRectangle(0,0,500,300));
  dl.push_back(DrawableFillColor("yellow"));
  dl.push_back(DrawableTranslation(250,150));
  dl.push_back(DrawablePolygon(star));
  dl.push_back(DrawableTranslation(50-250,25-150));
  dl.push_back(DrawableScaling(.5,.5));
  dl.push_back(DrawablePolygon(star));
  dl.push_back(DrawablePopGraphicContext());
  g.draw(dl);
}

The large star has a radius of 100, the 6 smaller stars have a radius of 10.

test text

A Gentle Introduction to
C++ Programming

Tutorial: Using and reusing stars

1. Vietnam

2. Panama

3. Bosnia and Herzegovina

4. Democratic Republic of Congo (formerly Zaire)

A Gentle Introduction to C++ Programming

Tutorial: Using and reusing stars

1. Vietnam

2. Panama

3. Bosnia and Herzegovina

4. Democratic Republic of Congo (formerly Zaire)

A Gentle Introduction to
C++ Programming