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：\n");
28
29 scanf("%d%d", &x0, &y0);
30
31 printf("Please input end point：\n");
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 }
