Demo thuật toán tổng quát

// Graphics.cpp
// ES
// 2009 11 10

#include "Graphics.h"
#include "math.h"

#define Round(a) int(a+0.5)

int pattern[8]={1,1,1,1,0,0,0,0};

void CGraphics::PutPixel(int x,int y,colorentry c)
{
	glColor3ub(c.Red,c.Green,c.Blue);
	glBegin(GL_POINTS);
		glVertex2i(x,y);
	glEnd();
}

colorentry CGraphics::GetPixel(int x,int y)
{
	GLubyte Color[3];
	float Pos[4];
	glRasterPos2d(x,y);
	glGetFloatv(GL_CURRENT_RASTER_POSITION,Pos);
	glReadPixels(Pos[0],Pos[1],1,1,GL_RGB,GL_UNSIGNED_BYTE,Color);
	return colorentry(Color[0],Color[1],Color[2]);
}

void CGraphics::DrawLine_OpenGL(int x1,int y1,int x2,int y2)
{
	glBegin(GL_LINES);
		glVertex2i(x1,y1);
		glVertex2i(x2,y2);
	glEnd();
}// CGraphics::DrawLine_OpenGL

void CGraphics::SetColor(colorentry c)
{
	glColor3ub(c.Red,c.Green,c.Blue);
}

void CGraphics::SetColorPVA(colorentry c)
{
	m_color=c;
}

void CGraphics::SetPixel(int x,int y)
{
	glBegin(GL_POINTS);
		glVertex2f(x,y);
	glEnd();
}

void CGraphics::SetPixel(int x,int y,colorentry c)
{
	glColor3ub(c.Red,c.Green,c.Blue);
	glBegin(GL_POINTS);
		glVertex2f(x,y);
	glEnd();
}//CGraphics::SetPixel

void CGraphics::DrawLine_DDA(int x1, int y1, int x2, int y2)
{
	int x=x1;
	float y=y1;
	float m=(float)(y2-y1)/(x2-x1);
	SetPixel(x,y1);
	while (x
	{
		x++;
		y+=m;
		//SetPixel(x,Round(y));
		//SetPixel(x,pattern);
		glLineStipple (1, 0x00FA);   
	}
}//CGraphics::DrawLine_DDA


void CGraphics::DrawLine_DDA_Full(int x1, int y1, int x2, int y2)
{	
	CGraphics Point;
	float x,y,m;
	int dx=x2-x1, dy=y2-y1;
	if(dx==0 && dy==0)
		SetPixel(0,0,m_color);
	if(abs(dx) > abs(dy)) // Truong hop 1-2
	{
		m=float(dy)/dx;
		int k=dx > 0 ? 1:-1;
		x=x1; y=y1;
		for(int i=0;i
		{
			PutPixel(Round(x),Round(y),m_color);
			x+=k;
			y+=m*k;
		}
	}
	else
	{
		m=float(dx)/dy;
		int k = dy > 0 ? 1 : -1;
			x = x1; y = y1;
			for (int i=0; i
			{
				PutPixel(Round(x), Round(y), m_color);
				y += k;
				x += m*k;
			}
	}
}

void hoanvi(int &a, int &b)
{	a = a ^ b;
	b = a ^ b;
	a = a ^ b;
}

// Hàm Line DDA ở dạng tổng quát.
void CGraphics::DrawLine_DDA_Full_2(int x1, int y1, int x2, int y2)
{	float dx, dy, x, y;
	float p;
	dx = x2 - x1;
	dy = y2 - y1;
	if(abs(dx) >= abs(dy))
	{	if(x1 > x2)
		{	hoanvi(x1, x2);
			hoanvi(y1, y2);
		}
		p = (float)(y2 - y1)/(x2 - x1);
		y = y1;
		for(x = x1; x < x2; x++)
		{	SetPixel(x, Round(y));
			y += p;
		}
	}
	else
	{	if(y1 > y2)
		{	hoanvi(x1, x2);
			hoanvi(y1, y2);
		}
		x = x1;
		p = (float)(x2 - x1)/(y2 - y1);
		for(y = y1; y < y2; y++)
		{	SetPixel(Round(x), y);
			x += p;
		}
	}
}

void CGraphics::DrawLine_Bresenham(int x1, int y1, int x2, int y2)
{
	int x=x1, y=y1;
	int dx=x2-x1, dy=y2-y1;
	int c1=(dy<<1); //2*dy
	int c2=((dy-dx)<<1);//(dy-dx)*2
	int p=(dy<<1)-dx; //2*dy-dx
	SetPixel(x,y);
	for(int i=x1;i
	{
		if(p<0)
			p+=c1;
		else
		{
			p+=c2;
			y++;
		}
		x++;
		SetPixel(x,y);
	}
}

void HoanVi4So(int &x1, int &y1, int &x2, int &y2)
{
	int a, b;
	a = x1;
	b = y1;

	x1 = x2;
	y1 = y2;

	x2 = a;
	y2 = b;
}

void CGraphics::DrawLine_MidPoint(int x1, int y1, int x2, int y2)
{
	int Dx, Dy, p, c1, c2;
	int x, y;
	int i, dx, dy;

	if(x1 > x2)
		HoanVi4So(x1, y1, x2, y2);

	Dx = x2 - x1;
	Dy = y2 - y1;

	dx = (Dx >= 0) ? 1 : -1;
	dy = (Dy >= 0) ? 1 : -1;

	Dx = abs(Dx);
	Dy = abs(Dy);

	p = 2*Dy - Dx;
	c1 = 2*Dy;
	c2 = 2*(Dy - Dx);

	x = x1;
	y = y1;

	SetPixel(x,y);

	for(i=0; i
	{
		if(p < 0)
			p += c1;
		else
		{
			p += c2;
			y += dy;
		}
		x += dx;
		SetPixel(x,y);
	}
}

// Thuật toán Line MidPiont dành cho cả 8 trường hợp
void CGraphics::DrawLine_MidPoint8th(int x1, int y1, int x2, int y2)
{	int dx, dy, x, y, c1, c2, p;
	dx = abs(x2 - x1);
	dy = abs(y2 - y1);
	p = (dy<<1) - dx;
	if(abs(dx) >= abs(dy))
	{	if(x1 > x2)
		{	hoanvi(x1, x2);
			hoanvi(y1, y2);
		}
		x = x1;
		y = y1;
		c1 = (dy<<1);//dy*2
		c2 = ((dy - dx)<<1); // (dy-dx)*2
		SetPixel(x, y);
		while(x < x2)
		{	if(p < 0)	p += c1;
			else
			{	p += c2;
				if(y1 > y2)	y--;
				else		y++;
			}
			++x;
			SetPixel(x, y);
		}
	}
	else
	{	if(y1 > y2)
		{	hoanvi(x1, x2);
			hoanvi(y1, y2);
		}
		x = x1; y = y1;
		c1 = (dx<<1); c2 = ((dy - dx)<<1); // dich phai
		SetPixel(x, y);
		while(y < y2)
		{	if(p < 0)	p += c1;
			else
			{	p += c2;
				if(x1 > x2)	x--;
				else		x++;
			}
			++y;
			SetPixel(x, y);
		}
	}
}

void CGraphics::Set8Pixel(int xc, int yc, int x, int y)
{
	SetPixel(xc+x,yc+y);
	SetPixel(xc+x,yc-y);
	SetPixel(xc-x,yc+y);
	SetPixel(xc-x,yc-y);
	SetPixel(xc+y,yc+x);
	SetPixel(xc+y,yc-x);
	SetPixel(xc-y,yc+x);
	SetPixel(xc-y,yc-x);	
}

void CGraphics::DrawCircle_MidPoint(int xc, int yc, int r)
{
	int x = 0, y = r;
	Set8Pixel(xc, yc, x, y);
	int p = 1-r;
	while (x < y)
	{
		if(p < 0)
			p += 2*x + 3;
		else
		{
			p += 2*(x - y) + 5; // luu ý: mấy chổ nhân 2 có để dịch trai
			y--;
		}
		x++;
		Set8Pixel(xc, yc, x, y);
	}
}

void CGraphics::DrawCicle_MidPointFull(int xc, int yc, int r)
{
	int x, y, p;
	x = 0; y = r; 
	Set8Pixel(xc, yc, x, y);
	p = 5/4 - r;
	while(x < y)
	{
		if(p < 0)
			p += 2*x + 3;
		else
		{
			p += 2*(x - y) + 5;
			y--;
		}
		x++;
		Set8Pixel(xc, yc, x+xc, y+yc);
		Set8Pixel(xc, yc, x+xc, -y+yc);
		Set8Pixel(xc, yc, -x+xc, y+yc);
		Set8Pixel(xc, yc, -x+xc, -y+yc);
	}
}

// Vẽ Elip bằng thuật toán Bresnham
void CGraphics::Set4Pixel(int xc, int yc, int x, int y)
{	SetPixel(xc + x, yc + y);
	SetPixel(xc - x, yc + y);
	SetPixel(xc + x, yc - y);
	SetPixel(xc - x, yc - y);
}
void CGraphics::DrawElip_Bresenham(int xc, int yc, int a, int b)
{	long x, y, dx, dy, rx, ry, p; // d= delta
	rx = a * a; ry = b * b;
	x = 0; y = b;
	dx = 0; dy = (rx << 1) * y;
	Set4Pixel(xc, yc, x, y);
	p = Round(ry - (rx * b) + (0.25 * rx));
	while (dx < dy)
	{	x++;
		dx += ry<<1;
		if(p < 0)	p += dx+ry;
		else
		{	y--;
			dy -= rx<<1;
			p += ry + dx - dy;
		}
		Set4Pixel(xc, yc, x, y);
	}
	p = Round(ry * (x+0.5)*(x+0.5) + rx*(y-1)*(y-1) - rx*ry);
	while (y>0)
	{	y--;
		dy -= rx<<1;
		if(p>0)		p += rx - dy;
		else
		{	x++;
			dx += ry<<1;
			p += dx + rx - dy;
		}
		Set4Pixel(xc, yc, x, y);
	}
}