基于opengl实现多段bezier曲线拼接（基于opengl实现多段bezier曲线拼接）

本文实例为大家分享了OpenGL实现多段Bezier曲线拼接的具体代码，供大家参考，具体内容如下

运行程序的交互方式有点类似corelDraw中的自由曲线绘制，或者photoShop中的钢笔自由路径绘制。

截图：

将BezierCurve封装成了一个类，代码如下：

1. #ifndef _BEZIERCURVE_H
2. #define _BEZIERCURVE_H
4. #include "vec3.hpp"
5. #include <vector>
6. #include <iostream>
7. #include <gl/glut.h>
9. using namespace std;
10. //// 3次bezier曲线: 四个控制节点。曲线经过首末两个顶点。
12. class BezierCurve
13. {
14. public:
15. //cell一共有四个控制顶点
16. // -cell经过V0和V3顶点，
17. // -cell的始端相切于直线：(V0, V1) 和末端相切于(V2,V3)
18. class BezierCell
19. {
20. public:
21. BezierCell(int i0, int i1, int i2, int i3)
22. {
23. setValue(i0, i1, i2, i3);
24. }
26. void setValue(int i0, int i1, int i2, int i3)
27. {
28. ctrlVertxIndex[0] = i0;
29. ctrlVertxIndex[1] = i1;
30. ctrlVertxIndex[2] = i2;
31. ctrlVertxIndex[3] = i3;
32. }
33. const int operator[](int index) const
34. {
35. if (index > 3 || index < 0)
36. return -1;
38. return ctrlVertxIndex[index];
39. }
40. int ctrlVertxIndex[4];
41. };
43. enum eventType
44. {
45. LButtonDown = 0,
46. MouseMove = 1,
47. LButtonUp = 2
48. };
50. enum { Bezier3CtrlPnt = 4 };
52. BezierCurve() { clear(); }
53. ~BezierCurve(){}
55. void begin()
56. {
57. // 开启求值器
58. glEnable(GL_MAP1_VERTEX_3);
59. clear();
60. }
62. void mouseSynchro(eventType type, const Vec3d& v) //响应鼠标motion
63. {
64. //////////////////////////////////////////////////////////////////////////
65. //LButtonDown: 压入点
66. if (type == LButtonDown)
67. {
68. if (isFirstRender) //for the first cell
69. {
70. vertexVector.push_back(v); //push V0...
71. vertexVector.push_back(v); //push V1...
72. }
73. else if ( cellRenderState() == cellRenderImple::Push ) //for any cell
74. {
75. vertexVector.push_back(v); //push V2...
76. vertexVector.push_back(v); //push V3...
78. cellRenderState.setChange(); //set the flag to change V3
79. cellNum++; //increase the cell counter
80. }
81. }
82. //////////////////////////////////////////////////////////////////////////
83. //MouseMove: 动态更新相应的顶点数据
84. else if (type == MouseMove)
85. {
86. if (isFirstRender) //for the first cell
87. {
88. vertexVector.back() = v; //change the V1 immediately
89. }
90. else if ( cellRenderState() == cellRenderImple::Change )//for any cell
91. {
92. int vecSize = vertexVector.size();
93. vertexVector[vecSize-2] = v; //change the V2 immediately
94. }
95. }
97. //////////////////////////////////////////////////////////////////////////
98. //LButtonUp: 为拼接做准备
99. else if (type == LButtonUp)
100. {
101. if (isFirstRender)
102. {
103. //只有第一个BezierCell可以编辑bezierCell的起始段:(V0,V1)
104. isFirstRender = false;
105. }
106. else if ( cellRenderState() == cellRenderImple::Change)
107. {
108. //if finish the current cell's render
109. //利用v1和中点v0计算出v2：(v1 + v2) / 2 = v0
110. //next cell begin: push the next cell's V1...
111. int vecSize = vertexVector.size();
112. Vec3d v0 = vertexVector[vecSize-1];
113. Vec3d v1 = vertexVector[vecSize-2];
114. Vec3d v2 = 2 * v0 - v1;
115. vertexVector.push_back(v2);
117. //重置cellRenderFlag
118. cellRenderState.setPush();
119. }
120. }
121. //////////////////////////////////////////////////////////////////////////
122. //更新数组的长度
123. _updateVertexNum();
124. }
126. void end()
127. {
128. glDisable(GL_MAP1_VERTEX_3);
129. }
131. void renderCurve()
132. {
133. //////////////////////////////////////////////////////////////////////////
134. //rendering vertex...
135. for (int i=0; i<vertexVector.size(); i++)
136. {
137. Vec3d v = vertexVector[i];
138. glBegin(GL_POINTS);
139. glVertex3dv(v.getValue());
140. glEnd();
141. }
143. //////////////////////////////////////////////////////////////////////////
144. //rendering moving tangent(切线)
145. //(vertexNum-1, vertexNum-2)
146. if ( vertexNum>=2 )
147. {
148. glEnable(GL_LINE_STIPPLE);
149. {
150. glLineStipple(1, 0x0101);
151. glBegin(GL_LINES);
152. {
153. Vec3d v1 = vertexVector[vertexNum-1];
154. Vec3d v2 = vertexVector[vertexNum-2];
155. glVertex3dv(v1.getValue());
156. glVertex3dv(v2.getValue());
157. } glEnd();
158. }glDisable(GL_LINE_STIPPLE);
159. }
161. //////////////////////////////////////////////////////////////////////////
162. //if ( !_check() )
163. // return;
165. //rendering bezier cells...
166. system("CLS");
167. for (int i=0; i<cellNum; i++)
168. {
169. int pos = i * 3;
170. if ( (pos+3) < vertexNum )
171. renderBezierCell( BezierCell(pos, pos+1, pos+2, pos+3) );
172. }
173. //////////////////////////////////////////////////////////////////////////
174. }
176. // 3次bezier曲线经过vetex0和vextex3
177. void renderBezierCell(const BezierCell& cell)
178. {
179. double *pBuffer = new double[Bezier3CtrlPnt * 3];
181. cout << "----------------------------------------------------" << endl;
183. cout << "Vertex number : " << vertexNum << endl;
184. cout << "Cell number : " << cellNum << endl;
185. cout << "The render cell: " << cell[0] << " " << cell[1] << " " << cell[2] << " " << cell[3] << endl;
187. for (int i = 0, bg = 0; i<4; i++)
188. {
189. Vec3d v = vertexVector[ cell[i] ];
190. pBuffer[bg++] = v.x();
191. pBuffer[bg++] = v.y();
192. pBuffer[bg++] = v.z();
194. cout << v.x() << " " << v.y() << " " << v.z() << endl;
195. }cout << "----------------------------------------------------" << endl;
197. glMap1d(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, Bezier3CtrlPnt, pBuffer);
198. glBegin(GL_LINE_STRIP);
199. {
200. for (int i = 0; i <= 30; i++)
201. glEvalCoord1f((GLfloat) i/30.0f);
202. } glEnd();
204. delete pBuffer; pBuffer = 0;
205. }
207. void clear()
208. {
209. cellNum = 0;
210. vertexNum = 0;
212. isFirstRender = true;
214. vertexVector.clear();
215. }
216. protected:
217. bool _check() { vertexNum =vertexVector.size();
218. return vertexNum == (cellNum - 1) * 3 + 4; }
219. void _updateVertexNum() { vertexNum=vertexVector.size();}
221. int cellNum; //单元个数
222. int vertexNum; //顶点个数
224. bool isFirstRender; //首次标志
225. std::vector<Vec3d> vertexVector; //顶点数组
227. class cellRenderImple
228. {
229. public:
230. enum RenderStep
231. {
232. Push = 0,
233. Change = 1
234. };
235. cellRenderImple(){ setPush(); }
236. bool operator()(void) { return flag; }
237. void setPush() { flag = Push; }
238. void setChange() { flag = Change; }
240. RenderStep flag; //cell的渲染状态
241. } cellRenderState;
242. };

测试程序如下：

1. #include <iostream>
2. #include <vector>
3. #include <GL/glut.h>
5. #include "BezierCurve.h"
7. using namespace std;
9. enum WindowSize{
10. WinWidth = 1024,
11. WinHeight = 768
12. };
14. int g_Viewport[4];
15. double g_ModelMatrix[16];
16. double g_ProjMatrix[16];
17. BezierCurve myBezier;
19. //////////////////////////////////////////////////////////////////////////
20. void init();
21. void display();
22. void reshape(int w, int h);
23. void keyboard(unsigned char key, int x, int y);
24. void mouse(int button, int state, int x, int y);
25. void motion(int x, int y);
27. int main(int argc, char** argv)
28. {
29. glutInit(&argc, argv);
30. glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
31. glutInitWindowSize (WinWidth, WinHeight);
32. glutInitWindowPosition (100, 100);
33. glutCreateWindow (argv[0]);
35. 以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。
37. init ();
38. glutDisplayFunc(display);
39. glutReshapeFunc(reshape);
40. glutKeyboardFunc (keyboard);
41. glutMouseFunc(mouse);
42. glutMotionFunc(motion);
44. glutMainLoop();
46. return 0;
47. }
49. void init(void)
50. {
51. glClearColor(0.0, 0.0, 0.0, 0.0);
52. glShadeModel(GL_SMOOTH);
54. myBezier.begin();
55. }
57. void display(void)
58. {
59. glClear(GL_COLOR_BUFFER_BIT);
61. glColor3f(1.0, 1.0, 0.0);
62. glPointSize(5.0);
64. glPushMatrix();
65. {
66. myBezier.renderCurve();
67. }glPopMatrix();
69. glutSwapBuffers();
70. }
72. void reshape(int w, int h)
73. {
74. glViewport(0, 0, (GLsizei) w, (GLsizei) h);
75. glMatrixMode(GL_PROJECTION);
76. glLoadIdentity();
77. if (w <= h)
78. glOrtho(-5.0, 5.0, -5.0*(GLfloat)h/(GLfloat)w,
79. 5.0*(GLfloat)h/(GLfloat)w, -5.0, 5.0);
80. else
81. glOrtho(-5.0*(GLfloat)w/(GLfloat)h,
82. 5.0*(GLfloat)w/(GLfloat)h, -5.0, 5.0, -5.0, 5.0);
83. glMatrixMode(GL_MODELVIEW);
84. glLoadIdentity();
85. }
87. void keyboard(unsigned char key, int x, int y)
88. {
89. switch (key) {
90. case 27:
91. exit(0);
92. break;
93. }
94. }
96. void mouse(int button, int state, int x, int y)
97. {
98. double vertex[3];
100. //获取矩阵信息
101. glGetIntegerv(GL_VIEWPORT, g_Viewport);
102. glGetDoublev(GL_MODELVIEW_MATRIX, g_ModelMatrix);
103. glGetDoublev(GL_PROJECTION_MATRIX, g_ProjMatrix);
105. y = g_Viewport[3] - y;
106. gluUnProject( x, y, 0,
107. g_ModelMatrix, g_ProjMatrix, g_Viewport,
108. &vertex[0], &vertex[1], &vertex[2] );
110. if (button==GLUT_LEFT && state==GLUT_DOWN)
111. {
112. myBezier.mouseSynchro( BezierCurve::LButtonDown, vertex );
113. glutSetCursor( GLUT_CURSOR_RIGHT_ARROW );
114. }
115. else if (button == GLUT_LEFT && state == GLUT_UP)
116. {
117. myBezier.mouseSynchro( BezierCurve::LButtonUp, vertex );
118. }
120. glutPostRedisplay();
121. }
123. //////////////////////////////////////////////////////////////////////////
124. // 计算控制节点
125. void motion(int x, int y)
126. {
127. double vertex[3];
129. glutSetCursor( GLUT_CURSOR_CROSSHAIR );
130. y = g_Viewport[3] - y;
132. gluUnProject( x, y, 0,
133. g_ModelMatrix, g_ProjMatrix, g_Viewport,
134. &vertex[0], &vertex[1], &vertex[2] );
136. myBezier.mouseSynchro( BezierCurve::MouseMove, vertex );
137. glutPostRedisplay();
138. }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。

原文链接：https://blog.csdn.net/ryfdizuo/article/details/4728785

如果您对该产品感兴趣，请填写办理（客服微信：xiaoxiongyidong）

您的姓名 *

身份证号码 *

手机号码 *

选择地区 *

详细地址 *

留言备注 *