中点Brehensam画线算法

  1 #include<stdio.h>
  2 
  3 #include<stdlib.h>
  4 
  5 #include"graphics.h"
  6 
  7  
  8 
  9 //函数声明
 10 
 11 void MidBrehansem(int x0, int y0, int x1, int y1);  //中点MidBrehansem算法
 12 
 13 void swap(int &x, int &y);  //利用引用传递交换值
 14 
 15  
 16 
 17 int main()
 18 
 19 {
 20 
 21     int gdriver = DETECT, gmode;
 22 
 23     int x0, y0, x1, y1;
 24 
 25  
 26 
 27     printf("Please input start point：
");
 28 
 29     scanf("%d%d", &x0, &y0);
 30 
 31     printf("Please input end point：
");
 32 
 33     scanf("%d%d", &x1, &y1);
 34 
 35  
 36 
 37     initgraph(&gdriver, &gmode, "");
 38 
 39  
 40 
 41     MidBrehansem(x0, y0, x1, y1);
 42 
 43    
 44 
 45     system("pause");
 46 
 47  
 48 
 49     closegraph();
 50 
 51  
 52 
 53     return 0;
 54 
 55 }
 56 
 57  
 58 
 59 //中点MidBrehansem算法
 60 
 61 void MidBrehansem(int x0, int y0, int x1, int y1)
 62 
 63 {
 64 
 65     int  dx, dy,i,di;
 66 
 67     double k;
 68 
 69  
 70 
 71     if (x0 > x1)
 72 
 73     {
 74 
 75         swap(x0, x1);
 76 
 77         swap(y0, y1);
 78 
 79     }
 80 
 81  
 82 
 83     int x = x0, y = y0;     //定义到前面会从x1，y1开始画线
 84 
 85  
 86 
 87     dx = x1 - x0;
 88 
 89     dy = y1 - y0;
 90 
 91  
 92 
 93     k = 1.0*dy / dx;
 94 
 95     i = (abs(dy)>abs(dx)) ? abs(dy): abs(dx);
 96 
 97  
 98 
 99     if (k >= 1)
100 
101     {
102 
103         di = 2 * dx + dy;
104 
105         while (i--)
106 
107         {
108 
109             putpixel(x, y, RED);
110 
111             if (di >= 0)
112 
113             {
114 
115                 di += 2 * (dx - dy);
116 
117                 x++;
118 
119             }
120 
121             else
122 
123                 di += 2 * dx;
124 
125  
126 
127             y++;
128 
129         }
130 
131     }
132 
133     else if (k >= 0 && k < 1)
134 
135     {
136 
137         di = dx - 2 * dy;
138 
139         while (i--)
140 
141         {
142 
143             putpixel(x, y, YELLOW);
144 
145             if (di < 0)
146 
147             {
148 
149                 di += 2 * (dx - dy);
150 
151                 y++;
152 
153             }
154 
155             else
156 
157                 di += (-2)*dy;
158 
159  
160 
161             x++;
162 
163         }
164 
165     }
166 
167     else if (k >= -1 && k < 0)
168 
169     {
170 
171         di = -dx - 2 * dy;
172 
173         while (i--)
174 
175         {
176 
177             putpixel(x, y, YELLOW);
178 
179             if (di >= 0)
180 
181             {
182 
183                 di += (-2)*(dx + dy);
184 
185                 y--;
186 
187             }
188 
189             else
190 
191                 di += (-2)*dy;
192 
193  
194 
195             x++;
196 
197         }
198 
199     }
200 
201     else
202 
203     {
204 
205         di = -2 * (dx + dy);
206 
207         while (i--)
208 
209         {
210 
211             putpixel(x, y, WHITE);
212 
213             if (di < 0)
214 
215             {
216 
217                 di += (-2)*(dx + dy);
218 
219                 x++;
220 
221             }
222 
223             else
224 
225                 di += (-2)*dx;
226 
227  
228 
229             y--;
230 
231         }
232 
233     }
234 
235    
236 
237 }
238 
239  
240 
241 //利用引用传递交换值
242 
243 void swap(int &x, int &y)
244 
245 {
246 
247     int t;
248 
249  
250 
251     t = x;
252 
253     x = y;
254 
255     y = t;
256 
257 }