OpenGL: OpenGL下通过鼠标动态绘制三次Bezier曲线

三次Bezier曲线有四个控制节点。利用OpenGL的一维求值器原理。

 

程序介绍：

第一次鼠标左键down点为0控制节点， 按住左键移动动态移动确定1控制节点，

第二次鼠标左键down点3控制节点，按住左键移动，确定2控制节点。

程序运行的效果图：

 

 代码只是实现了绘制一段Bezier如下：

#include <GL/glut.h>#include <iostream>#include <vector>using namespace std;#define KEY_POINT_NUM 6#define CONTROL_POINT_NUM 4#define WinWidth1024#define WinHeight768#define DrawOneLine(x1, y1, z1, x2, y2, z2) glBegin(GL_LINES);\glVertex3d( (x1), (y1), (z1) ); glVertex3d( (x2), (y2), (z2) ); glEnd(); enumDRAW_FLAG{FIRST_LINE = 0,SECOND_LINE = 1,END = 2};intg_iFlag = FIRST_LINE;intg_Viewport[4];boolg_bIsDown = false;doubleg_ModelMatrix[16];doubleg_ProjMatrix[16];double  g_Vertex[KEY_POINT_NUM][3];//6个关键点，其中四个为控制结点。doubleg_ControlVertex[CONTROL_POINT_NUM+3][3];//////////////////////////////////////////////////////////////////////////void init();void display();void reshape(int w, int h);void keyboard(unsigned char key, int x, int y);void mouse(int button, int state, int x, int y);void motion(int x, int y);int main(int argc, char** argv){glutInit(&argc, argv);glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);glutInitWindowSize (WinWidth, WinHeight);glutInitWindowPosition (100, 100);glutCreateWindow (argv[0]);init ();glutDisplayFunc(display);glutReshapeFunc(reshape);glutKeyboardFunc (keyboard);glutMouseFunc(mouse);glutMotionFunc(motion);glutMainLoop();return 0;}void init(void){   glClearColor(0.0, 0.0, 0.0, 0.0);   glShadeModel(GL_SMOOTH);}void display(void){glClear(GL_COLOR_BUFFER_BIT);glPointSize(5.0);glColor3f(1.0, 1.0, 0.0);glEnable(GL_LINE_STIPPLE);{glLineStipple(1, 0x0101);if (FIRST_LINE==g_iFlag){DrawOneLine( g_Vertex[0][0], g_Vertex[0][1], g_Vertex[0][2],  g_Vertex[1][0], g_Vertex[1][1], g_Vertex[1][2] );DrawOneLine( g_Vertex[0][0], g_Vertex[0][1], g_Vertex[0][2],     g_Vertex[2][0], g_Vertex[2][1], g_Vertex[2][2] );glBegin(GL_POINTS);{glVertex3dv(g_Vertex[0]);glVertex3dv(g_Vertex[1]);glVertex3dv(g_Vertex[2]);} glEnd();}else if (SECOND_LINE==g_iFlag){DrawOneLine( g_Vertex[3][0], g_Vertex[3][1], g_Vertex[3][2],  g_Vertex[4][0], g_Vertex[4][1], g_Vertex[4][2] );DrawOneLine( g_Vertex[3][0], g_Vertex[3][1], g_Vertex[3][2],  g_Vertex[5][0], g_Vertex[5][1], g_Vertex[5][2] );glBegin(GL_POINTS);{glVertex3dv(g_Vertex[0]);glVertex3dv(g_Vertex[3]);glVertex3dv(g_Vertex[4]);glVertex3dv(g_Vertex[5]);} glEnd();}}glDisable(GL_LINE_STIPPLE);//提取控制节点，绘制bezier曲线。//////////////////////////////////////////////////////////////////////////glBegin(GL_POINTS);{for (int i = 0; i < CONTROL_POINT_NUM; i++) glVertex3dv(&g_ControlVertex[i][0]);} glEnd();glColor3f(1.0f, 1.0f, 1.0f);glMap1d(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, CONTROL_POINT_NUM, &g_ControlVertex[0][0]);glEnable(GL_MAP1_VERTEX_3);glBegin(GL_LINE_STRIP);{for (int i = 0; i <= 30; i++) glEvalCoord1f((GLfloat) i/30.0f);} glEnd();//////////////////////////////////////////////////////////////////////////glutSwapBuffers();}void reshape(int w, int h){   glViewport(0, 0, (GLsizei) w, (GLsizei) h);   glMatrixMode(GL_PROJECTION);   glLoadIdentity();   if (w <= h)      glOrtho(-5.0, 5.0, -5.0*(GLfloat)h/(GLfloat)w,                5.0*(GLfloat)h/(GLfloat)w, -5.0, 5.0);   else      glOrtho(-5.0*(GLfloat)w/(GLfloat)h,                5.0*(GLfloat)w/(GLfloat)h, -5.0, 5.0, -5.0, 5.0);   glMatrixMode(GL_MODELVIEW);   glLoadIdentity();}void keyboard(unsigned char key, int x, int y){   switch (key) {      case 27:         exit(0);         break;   }}void mouse(int button, int state, int x, int y){//获取矩阵信息glGetIntegerv(GL_VIEWPORT, g_Viewport);glGetDoublev(GL_MODELVIEW_MATRIX, g_ModelMatrix);glGetDoublev(GL_PROJECTION_MATRIX, g_ProjMatrix);if (button==GLUT_LEFT && state==GLUT_DOWN){g_bIsDown = true;double _3dPoint[3];y = g_Viewport[3] - y;if (FIRST_LINE==g_iFlag){gluUnProject( x, y, 0,g_ModelMatrix, g_ProjMatrix, g_Viewport,&_3dPoint[0], &_3dPoint[1], &_3dPoint[2] );// 全部初始化for (int i=0; i<3; i++)g_ControlVertex[0][i] = g_Vertex[0][i] = _3dPoint[i];}else if (SECOND_LINE==g_iFlag){gluUnProject( x, y, 0,g_ModelMatrix, g_ProjMatrix, g_Viewport,&_3dPoint[0], &_3dPoint[1], &_3dPoint[2] );// 主要是保存v(3)for (int i=0; i<3; i++)g_ControlVertex[3][i] = g_Vertex[3][i] = _3dPoint[i];}}if (button==GLUT_LEFT && state==GLUT_UP){g_bIsDown = false;g_iFlag = (g_iFlag+1) % 3;glutSetCursor( GLUT_CURSOR_RIGHT_ARROW );}}//////////////////////////////////////////////////////////////////////////// 计算控制节点void motion(int x, int y){if ( !g_bIsDown )return;glutSetCursor( GLUT_CURSOR_CROSSHAIR );y = g_Viewport[3] - y;if ( FIRST_LINE==g_iFlag ){gluUnProject( x, y, 0,g_ModelMatrix, g_ProjMatrix, g_Viewport,&g_Vertex[1][0], &g_Vertex[1][1], &g_Vertex[1][2] );for (int i=0; i<3; i++){// 记录控制结点g_ControlVertex[1][i] = g_Vertex[1][i];// V0为V1和V2的中点g_Vertex[2][i] = 2 * g_Vertex[0][i] - g_Vertex[1][i];}}else if ( SECOND_LINE==g_iFlag ){gluUnProject( x, y, 0,g_ModelMatrix, g_ProjMatrix, g_Viewport,&g_Vertex[5][0], &g_Vertex[5][1], &g_Vertex[5][2] );for (int i=0; i<3; i++){// V3为V4和V5的中点g_Vertex[4][i] = 2 * g_Vertex[3][i] - g_Vertex[5][i];// 记录控制结点g_ControlVertex[2][i] = g_Vertex[4][i];}}glutPostRedisplay();}

有时间将进一步实现多段拼接。 

http://blog.csdn.net/ryfdizuo/article/details/4575913