C + + polygon scan conversion algorithm

　Recently learned computer graphics, wrote a polygon scan conversion algorithm, posted out to share;

MFC is not too clear, mainly using the OnDraw function ...

Please advise ...

void Cpolyfillview::ondraw (cdc* pDC)

{

cpolyfilldoc* PDoc = GetDocument ();

Assert_valid (PDOC);

Todo:add Draw code for native

const int pointnum=6; Polygon points.

/define the structure body for active side table aet and new edge table net/

typedef struct XET

{

float x;

float Dx,ymax;

Xet* Next;

}aet,net;

/definition point Structure body point*/

struct POINT

{

float x;

Float y;

}polypoint[pointnum]={250,50,550,150,550,400,250,250,100,350,100,100};//Polygon Vertices

mypoint[pointnum]={100,100,200,100,200,200,100,200};//Square

/compute the y-coordinate of the highest point (scan to this end) **/

int maxy=0;

int i;

for (i=0;i<pointnum;i++)

if (Polypoint[i].y>maxy)

MAXY=POLYPOINT[I].Y;

/* Initialize AET table/

AET *paet=new AET;

paet->next=null;

/Initialization NET Table * *

NET *pnet[1024];

for (i=0;i<=maxy;i++)

{

Pnet[i]=new NET;

pnet[i]->next=null;

}

/Scan and build net table * *

for (i=0;i<=maxy;i++)

{

for (int j=0;j<pointnum;j++)

if (polypoint[j].y==i)

{

if (polypoint[(j-1+pointnum)%pointnum].y>polypoint[j].y)

{

NET *p=new net;

p->x=polypoint[j].x;

p->ymax=polypoint[(j-1+pointnum)%pointnum].y;

P->dx= (polypoint[(j-1+pointnum)%pointnum].x-polypoint[j].x)/(polypoint[(J-1+pointnum)%POINTNUM].y-polypoint [J].y);

p->next=pnet[i]->next;

pnet[i]->next=p;

}

if (polypoint[(j+1+pointnum)%pointnum].y>polypoint[j].y)

{

NET *p=new net;

p->x=polypoint[j].x;

p->ymax=polypoint[(j+1+pointnum)%pointnum].y;

P->dx= (polypoint[(j+1+pointnum)%pointnum].x-polypoint[j].x)/(polypoint[(J+1+pointnum)%POINTNUM].y-polypoint [J].y);

p->next=pnet[i]->next;

pnet[i]->next=p;

}

}

}

/Establish and update the active side table aet/

for (i=0;i<=maxy;i++)

{

Compute new intersection x, update aet/

NET *p=paet->next;

while (p)

{

P->x=p->x + p->dx;

p=p->next;

}

New AET first sorted after update