【计算机图形学】c++ graphics.h DDA画线、中点画圆、中点画椭圆

源代码

// 画线_圆_椭圆.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include"stdafx.h"
#include
#include  // 这样引用 EasyX 图形库
#include
#include
#include
#include
using namespace std;

//DDA画线
void DDALine(int p0_x, int p0_y, int p1_x, int p1_y, COLORREF color){
     

	int dx = p1_x - p0_x, dy = p1_y - p0_y, steps, k;
	float xIncrement, yIncrement, xp = p0_x, yp = p0_y;
	color = YELLOW;
	if (abs(dx) > abs(dy))
		steps = abs(dx);
	else
		steps = abs(dy);

	xIncrement = ((float)dx) / steps;
	yIncrement = ((float)dy) / steps;

	putpixel((int)(xp + 0.5), (int)(yp + 0.5), color);
	for (k = 0; k < steps; k++){
     
		xp += xIncrement;
		yp += yIncrement;
		putpixel((int)(xp + 0.5), (int)(yp + 0.5), color);
	}
}

//中点画圆
void MidpointCircle(int x0, int y0, int r, int color)
{
     
	int x = 0, y = r;
	float d = 5.0 / 4 - r;
	color = GREEN;
	while (x <= y) {
     
		putpixel(x0 + x, y0 + y, color);
		putpixel(x0 + x, y0 - y, color);
		putpixel(x0 - x, y0 + y, color);
		putpixel(x0 - x, y0 - y, color);
		putpixel(x0 + y, y0 + x, color);
		putpixel(x0 + y, y0 - x, color);
		putpixel(x0 - y, y0 + x, color);
		putpixel(x0 - y, y0 - x, color);
		if (d<0)
			d += x*2.0 + 3;
		else {
     
			d += 2.0*(x - y) + 5; y--;
		}
		x++;
	}
}

//中点画椭圆
void elliosePlotPoints(int xCenter, int yCenter, int x, int y, COLORREF color){
     
	putpixel(xCenter + x, yCenter + y, color);
	putpixel(xCenter - x, yCenter + y, color);
	putpixel(xCenter + x, yCenter - y, color);
	putpixel(xCenter - x, yCenter - y, color);
}
void ellipseMidpoint(int xCenter, int yCenter, int rx, int ry, COLORREF color){
     
	int rx2 = rx*rx, ry2 = ry*ry;
	int tworx2 = 2 * rx2, twory2 = 2 * ry2;
	int p, x = 0, y = ry, px = 0, py = tworx2*y;
	elliosePlotPoints(xCenter, yCenter, x, y, color);
	p = (int)((ry2 - (rx2*ry) + 0.25*rx2) + 0.5);
	while (px < py){
     
		x++;
		px += twory2;
		if (p < 0)p += ry2 + px;
		else{
     
			y--;
			py -= tworx2;
			p += ry2 + px - py;
		}
		elliosePlotPoints(xCenter, yCenter, x, y, color);
	}
	p = (int)((ry2*(x + 0.5)*(x + 0.5) + rx2*(y - 1)*(y - 1) - rx2*ry2) + 0.5);
	while (y>0){
     
		y--;
		py -= tworx2;
		if (p > 0)p += rx2 - py;
		else{
     
			x++;
			px += twory2;
			p += rx2 - py + px;
		}
		elliosePlotPoints(xCenter, yCenter, x, y, color);
	}
}



void main()
{
     
	int x0, y0, x1, y1;
	initgraph(640, 480);
	DDALine(0, 0, 200, 200, 255);
	MidpointCircle(100, 100, 90, 255);
	ellipseMidpoint(200, 200, 180, 50, 255);
	_getch();
	closegraph();
}

测试结果