计算机图形学DDA画线法+中点画线法+Bresenham画线法

#include <cstdio>
#include <cstring>
#include <conio.h>
#include <graphics.h>
void line1(){
line(100, 100, 200, 400);
line(100, 400, 200, 100);
line(0, 200, 300, 300);
line(0, 300, 300, 200);
}void lineDDA(int x0, int y0, int x1, int y1, int color){
int x;
float dy, dx, y, m;
dx = x1 - x0;
dy = y1 - y0;
m = dy / dx;
y = y0;
for (x = x0; x <= x1; x++){
putpixel(x, (int)(y + 0.5), color);
y += m;
}
}void lineDDA(){
lineDDA(100, 100, 200, 400, RED);
lineDDA(100, 400, 200, 100, RED);
lineDDA(0, 200, 300, 300, RED);
lineDDA(0, 300, 300, 200, RED);
}void lineMidPoint(int x0, int y0, int x1, int y1, int color){
int x = x0, y = y0;
int a = y0 - y1, b = x1 - x0;
int cx = (b >= 0 ? 1 : (b = -b, -1));
int cy = (a <= 0 ? 1 : (a = -a, -1)); putpixel(x, y, color); int d, d1, d2;
if (-a <= b) // 斜率绝对值 <= 1
{
d = 2 * a + b;
d1 = 2 * a;
d2 = 2 * (a + b);
while (x != x1)
{
if (d < 0)
y += cy, d += d2;
else
d += d1;
x += cx;
putpixel(x, y, color);
}
}
else // 斜率绝对值 > 1
{
d = 2 * b + a;
d1 = 2 * b;
d2 = 2 * (a + b);
while (y != y1)
{
if (d < 0)
d += d1;
else
x += cx, d += d2;
y += cy;
putpixel(x, y, color);
}
}
}void lineMidPoint(){
lineMidPoint(100, 100, 200, 400, GREEN);
lineMidPoint(100, 400, 200, 100, GREEN);
lineMidPoint(0, 200, 300, 300, GREEN);
lineMidPoint(0, 300, 300, 200, GREEN);
}void lineBresenham(int x0, int y0, int x1, int y1, int color)
{
int dx = x1 - x0;
int dy = y1 - y0;
int ux = dx >0 ? 1 : -1;//x伸展方向
int uy = dy >0 ? 1 : -1;//y伸展方向
int dx2 = dx << 1;//x偏移量乘2
int dy2 = dy << 1;//y偏移量乘2
if (abs(dx)>abs(dy))
{//以x为增量方向计算
int e = -dx; //e = -0.5 * 2 * dx,把e 用2 * dx* e替换
int x = x0;
int y = y0;//起点y坐标
for (x = x0; x < x1; x += ux)
{
putpixel(x, y, color);
e = e + dy2;//来自 2*e*dx= 2*e*dx + 2dy （原来是 e = e + k）
if (e > 0)//e是整数且大于0时表示要取右上的点（否则是右下的点）
{
y += uy;
e = e - dx2;//2*e*dx = 2*e*dx - 2*dx (原来是 e = e -1)
}
}
}
else
{//以y为增量方向计算
int e = -dy; //e = -0.5 * 2 * dy,把e 用2 * dy* e替换
int x = x0;
int y = y0;
for (y = y0; y < y1; y += uy)
{
putpixel(x, y, color);
e = e + dx2;//来自 2*e*dy= 2*e*dy + 2dy （原来是 e = e + k）
if (e > 0)//e是整数且大于0时表示要取右上的点（否则是右下的点）
{
x += ux;
e = e - dy2;//2*e*dy = 2*e*dy - 2*dy (原来是 e = e -1)
}
}
}
}void lineBresenham1(int x0, int y0, int x1, int y1, long color)
{
int dx = abs(x1 - x0);
int dy = abs(y1 - y0);
int x = x0;
int y = y0;
int stepX = 1;
int stepY = 1;
if (x0 > x1) //从右向左画
stepX = -1;
if (y0 > y1)
stepY = -1; if (dx > dy) //沿着最长的那个轴前进
{
int e = dy * 2 - dx;
for (int i = 0; i <= dx; i++)
{
putpixel(x, y, color);
x += stepX;
e += dy;
if (e >= 0)
{
y += stepY;
e -= dx;
}
}
}
else
{
int e = 2 * dx - dy;
for (int i = 0; i <= dy; i++)
{
putpixel(x, y, color);
y += stepY;
e += dx;
if (e >= 0)
{
x += stepX;
e -= dy;
}
}
}
}void lineBresenham(){
lineBresenham1(100, 100, 200, 400, YELLOW);
lineBresenham1(100, 400, 200, 100, YELLOW);
lineBresenham1(0, 200, 300, 300, YELLOW);
lineBresenham1(0, 300, 300, 200, YELLOW);
}void showWord(int code){
outtextxy(200, 30, "单击右键退出");
switch (code){
case 1://原画
outtextxy(200, 10, "easyX系统画线算法");
break;
case 2://DDA算法
outtextxy(200, 10, "DDA算法");
break;
case 3://中点画线算法
outtextxy(200, 10, "中点画线算法");
break;
case 4://Bresenham算法
outtextxy(200, 10, "Bresenham算法");
break;
default:
line1();
break;
}
}void drawLine(int code){
switch (code){
case 1://原画
line1();
break;
case 2://DDA算法
lineDDA();
break;
case 3://中点画线算法
lineMidPoint();
break;
case 4://Bresenham算法
lineBresenham();
break;
default:
line1();
break;
}
}void drawLine(int x0,int y0,int x1,int y1,int code){
showWord(code);
switch (code){
case 1://原画
line(x0,y0,x1,y1);
break;
case 2://DDA算法
lineDDA(x0, y0, x1, y1,WHITE);
break;
case 3://中点画线算法
lineMidPoint(x0, y0, x1, y1, WHITE);
break;
case 4://Bresenham算法
lineBresenham1(x0, y0, x1, y1, WHITE);
break;
default:
line1();
break;
}
}void showWORDXY(int x, int y, int showX, int showY,int flag){
char dintX[5] = { 0 };
char dintY[5] = { 0 };
_itoa_s(showX, dintX, 10);//把整数showX转成字符串dintX
_itoa_s(showY, dintY, 10);//把整数showY转成字符串dintY
char str1[100] = "第一个点的坐标：（";//此时数组没有定义长度 元素的个数应该为strlen +1 因为字符串末尾有 '\0'结束
char str2[100] = "第二个点的坐标：（";
if (flag == 1){
// _countof(dintX)能够获取到数组中元素的个数 含‘\0’
strcat_s(str1, strlen(str1) + strlen(dintX)+1, dintX);
strcat_s(str1, strlen(str1) + strlen(",")+1, ",");
strcat_s(str1, strlen(str1) + strlen(dintY)+1, dintY);
strcat_s(str1, strlen(str1) + strlen(")")+1, ")");
outtextxy(x, y, str1);
}
else if (flag == 2){
strcat_s(str2, strlen(str2) + strlen(dintX)+1, dintX);
strcat_s(str2, strlen(str2) + strlen(",")+1, ",");
strcat_s(str2, strlen(str2) + strlen(dintY)+1, dintY);
strcat_s(str2, strlen(str2) + strlen(")")+1, ")");
outtextxy(x, y, str2);
}
}//调用easyX
void easyX(int code){
initgraph(640, 480); //初始化
showWord(code);
MOUSEMSG m; // 定义鼠标消息
int n=0;//读取两个点
int exit = false;
int x0=0, y0=0,x1=0,y1=0;
while (n<2 && !exit)
{
m = GetMouseMsg();
switch (m.uMsg)
{
case WM_RBUTTONDOWN:
outtextxy(200, 300, "再次点击键退出");
exit = true;
break; // 按鼠标右键退出程序
}
while (m.uMsg != WM_LBUTTONDOWN){
m = GetMouseMsg();
switch (m.uMsg)
{
case WM_RBUTTONDOWN:
outtextxy(200, 300, "再次点击键退出");
exit = true;
break; // 按鼠标右键退出程序
} }
while (m.uMsg != WM_LBUTTONUP){
m = GetMouseMsg(); cleardevice();
showWord(code);
if (n == 0){
showWORDXY(200, 430, x0, y0,1);
x0 = m.x;
y0 = m.y;
}
else{
showWORDXY(200, 430, x0, y0, 1);
showWORDXY(200, 450, x1, y1, 2);
x1 = m.x;
y1 = m.y;
}
}
n++;
if (n == 2){
//画线
drawLine(x0, y0, x1, y1, code);
//重置
n = 0;
}
}
//_getch(); //等待用户操作
closegraph(); //关闭图形
}int main(){
int n = 1;
printf("请选择画线算法画线：\n");
printf("1.easyX系统画线函数.\n");
printf("2.DDA画线算法函数.\n");
printf("3.中点画线算法函数.\n");
printf("4.Bresenham画线算法函数.\n");
printf("0.退出.\n");
while (n != 0){
scanf_s("%d", &n);
if (n == 0){
exit(0);
}
easyX(n);
}
return 0;
}
效果图：