About the drawing bottom algorithm

At ordinary times, used to the API, CDC and encapsulated internal functions, about drawing lines, draw a circle these things are at your fingertips ...

Recently learning computer graphics, have to go deep inside the bottom of the algorithm ...

Put a few code here to share!

(Only the MFC OnDraw function is given here)

First, draw the line of three algorithms:

1. DDA (Numerical differential) method:

void Cddalineview::ondraw (cdc* pDC)

{

cddalinedoc* PDoc = GetDocument ();

Assert_valid (PDOC);

Todo:add Draw code for native

int x,x0 (y0), X1 (+), y1 (500);

float dx,dy,y,k;

dx=x1-x0;

Dy=y1-y0;

K=DY/DX;

Y=y0;

for (x=x0;x<=x1;x++)

{

Pdc->setpixel (x, (int) (y+0.5), RGB (255,0,0));

Y+=k;

}

}

2. Midpoint Drawing line algorithm

void Cmidpointlineview::ondraw (cdc* pDC)

{

cmidpointlinedoc* PDoc = GetDocument ();

Assert_valid (PDOC);

Todo:add Draw code for native

int a,b,d1,d2,d,x,y;

int x0 (x1), y0 (500), y1;

A=y0-y1;

b=x1-x0;

D=2*a+b;

D1=2*a;

d2=2* (A+B);

x=x0;

Y=y0;

Pdc->setpixel (X,y,rgb (0,255,0));

while (X<X1)

{

if (d<0)

{

x + +;

y++;

D+=D2;

}

Else

{

x + +;

D+=D1;

}

Pdc->setpixel (X,y,rgb (0,255,0));

}

}

3. Bresenham algorithm:

void Cbresenhamline2view::ondraw (cdc* pDC)

{

cbresenhamline2doc* PDoc = GetDocument ();

Assert_valid (PDOC);

Todo:add Draw code for native

int x0 (y0), X1 (+), y1 (500);

int x,y,dx,dy;

dx=x1-x0;

Dy=y1-y0;

int e=-dx;

x=x0;

Y=y0;

for (int i=0;i<=dx;i++)

{

Pdc->setpixel (X,y,rgb (0,0,255));

x=x+1;

E=e+2*dy;

if (e>=0)

{

y++;

E=E-2*DX;

}

}

}

Second, the Midpoint Draw circle algorithm:

void Cmidpointcircleview::ondraw (cdc* pDC)

{

cmidpointcircledoc* PDoc = GetDocument ();

Assert_valid (PDOC);

Todo:add Draw code for native

int r=100; Radius

int m (+), n (250);//Center coordinates

int x,y;

float D;

x=0;

Y=0+r;

D=1.25-r;

Algorithm of midpoint drawing circle

Pdc->setpixel (M+x,n+y,rgb (255,0,0));

Pdc->setpixel (M+y,n+x,rgb (255,0,0));

Pdc->setpixel (M-x,n+y,rgb (255,0,0));

Pdc->setpixel (M+y,n-x,rgb (255,0,0));

Pdc->setpixel (M+x,n-y,rgb (255,0,0));

Pdc->setpixel (M-y,n+x,rgb (255,0,0));

Pdc->setpixel (M-x,n-y,rgb (255,0,0));

Pdc->setpixel (M-y,n-x,rgb (255,0,0));

while (x<=y)

{

if (d<0)

d+=2*x+3;

Else

{

d+=2* (x-y) +5;

y--;

}

x + +;

Pdc->setpixel (M+x,n+y,rgb (255,0,0));

Pdc->setpixel (M+y,n+x,rgb (255,0,0));

Pdc->setpixel (M-x,n+y,rgb (255,0,0));

Pdc->setpixel (M+y,n-x,rgb (255,0,0));

Pdc->setpixel (M+x,n-y,rgb (255,0,0));

Pdc->setpixel (M-y,n+x,rgb (255,0,0));

Pdc->setpixel (M-x,n-y,rgb (255,0,0));

Pdc->setpixel (M-y,n-x,rgb (255,0,0));

}

}