Fern

• Demonstration
• Description:
  • per pixel fern drawing animation (technically - drawing an IFS fractal)
• Functionality:
  • window with size of 25% size of the screen, located at 1/4^th of width and 1/4^th of height of the screen
  • per pixel fern drawing on the internal bitmap with size of the screen
  • fern image is drawn scaled to the window size always
  • no more than 256000 points of the fern should be drawn
  • fern should be drawn with RGB(0,200,0) color on the black background
  • the drawing should be flicker-free, image has to be scaled smoothly
  • drawing should be executed in background thread, to enable normal interaction with the window (scaling, moving, closing, ...)
  • exemplary code for fern drawing

    int n,c;
    double x,y,r,w,x1,y1;
    
    x = 1 / sqrt(2.0);
    y = x;
    
    for(n = 0; n < 256000; n++) {
    	c = 2 * (n % 2) - 1;
    	r = sqrt(x*x + y*y);
    	w = atan2(y,x);
    	x = r * cos(w - c * M_PI / 12.0);
    	y = r * sin(w - c * M_PI / 12.0);
    	int tmp = rand() % 100;
    	if(tmp<77) {
    		x1 = 0.85 * x + 0.04 * y;
    		y1 = -0.04 * x + 0.85 * y + 1.6;
    	}
    	else if(tmp<88) {
    		x1 = 0.2 * x - 0.26 * y;
    		y1 = 0.23 * x + 0.22 * y + 1.6;
    	}
    	else if(tmp<99) {
    		x1 = -0.15 * x + 0.28 * y;
    		y1 = 0.26 * x + 0.24 * y + 0.44;
    	}
    	else {
    		x1 = 0;
    		y1 = 0.16 * y;
    	}
    
    	x = x1;
    	y = y1;
    	SetPixel(hdc,(int)(x * cx/8.0 + cx/2),(int)(y * cy/10.0),RGB(0,200,0));
    }

    based on http://astronomy.swin.edu.au/~pbourke/fractals/ifs_fern_a/roger11.c
    hdc - display context handle, cx - width, cy - height
• Hints (WinApi):
  • #define _USE_MATH_DEFINES, #include <math.h>
  • SetStretchBltMode(), StretchBlt()
  • CreateThread(), CloseHandle()
• Hints (DotNet):
  • Graphics.InterpolationMode
  • using System.Threading
  • Thread(), ThreadStart()
• Approximate points:
  • window size and location: 1.0
  • fern drawing: 4.0
  • scaling quality: 1.0
  • background thread: 4.0

• Links for uploading:
  • Solutions
  • Corrections