vs2010+openGL绘制任意阶Beizer

/* key 'q' quit key 'c' clear screen key 'e' erase curve 鼠标左键点击空白处，添加点 鼠标左键点击点，选中点，此时拖动鼠标，可移动所选中的点 鼠标右键点击点，删除点 */ #include<cstdlib> #include<stdio.h> #include <gl/glut.h> void keyboard( unsigned char key , int x, int y ); #define MAX_CPTS 1000 // 控制点最大数目 const int MESH = 50; // 切分段数 float bPoints[MESH][3]; GLfloat cpts[MAX_CPTS][3]; GLfloat cpts2[MAX_CPTS][3]; // store points when calculate Bezier bool trackingMouse = false; int index = -1; int ncpts = 0 ; static int width = 500 , height = 500; // 绘制窗口的宽度和高度 void calPoint( float t ) // t is the parameter in Bezier Curve { for( int i = 0 ; i<ncpts ; i++ ) for( int j = 0 ; j<3 ; j++ ) cpts2[i][j] = cpts[i][j]; for( int i = 0 ; i<ncpts-1 ; i++ ) // recur times for( int j = 0 ; j<ncpts-1-i ; j++ ) for( int k =0 ; k<2 ; k++ ) // coordinate z is not calculated cpts2[j][k] = (1-t)*cpts2[j][k] + t*cpts2[j+1][k] ; } void drawCurves() { if( ncpts==1 ) return ; float interval = 1/(float)MESH; float t = 0; bPoints[0][0] = cpts[0][0]; bPoints[0][1] = cpts[0][1]; bPoints[MESH-1][0] = cpts[ncpts-1][0]; bPoints[MESH-1][1] = cpts[ncpts-1][1]; for( int k=1 ; k<MESH-1 ; k++ ) { t+=interval; calPoint( t ); for( int i=0 ; i<2 ; i++ ) bPoints[k][i] = cpts2[0][i] ; } glColor3f(1.0 , 0.0 , 0.0 ); // chang color to red glBegin( GL_LINE_STRIP ); for( int i=0 ; i<MESH ; i++ ) glVertex3fv( bPoints[i] ); glEnd(); } void drawPoints() { glColor3f( 0.0 , 0.0 , 0.0); // change color to black glBegin(GL_POINTS); for( int i=0 ; i<ncpts ; i++) { glVertex3fv(cpts[i]); } glEnd(); glColor3f( 0.0 , 1.0 , 1.0 ); // change color to yellow glBegin(GL_LINE_STRIP); for( int i=0 ; i<ncpts ; i++ ) glVertex3fv( cpts[i] ); glEnd(); } void showList() { printf("========\n"); for( int i=0 ; i<ncpts ; i++ ) { printf("\t\t\t%f %f\n" , cpts[i][0] , cpts[i][1] ); } printf("========\n"); } void drawElements() { drawPoints(); drawCurves(); showList(); } void display() { glClear(GL_COLOR_BUFFER_BIT); } int check( float x , float y ) { // if point(x , y ) is close to any point in array 'cpts' , return the index , else return -1 for( int i=0 ; i<ncpts ; i++ ) { if( (cpts[i][0]-x)*(cpts[i][0]-x) + (cpts[i][1]-y)*(cpts[i][1]-y) <=0.0003 ) return i; } return -1; } void addPoint( float wx , float wy ) { // 判断是否还可以定义更多的控制点 if( ncpts == MAX_CPTS ) return ; // 储存控制点的位置 cpts[ncpts][0] = wx ; cpts[ncpts][1] = wy ; cpts[ncpts][2] = 0.0 ; ncpts++; glutPostRedisplay(); drawElements(); glFlush(); } void action_LeftDown( float wx , float wy) { index = check( wx , wy ); if( index>-1 ) { trackingMouse = true; printf("start tracking.\n"); } else addPoint( wx , wy ); } void action_LeftUp() { trackingMouse = false; } void action_DeletePoint(float wx , float wy) { printf( "delete point "); index = check(wx , wy ); if( index==-1 ) { return ; } else // delete the point chosen , and move the rest points forward { for( int i=index+1 , j = index ; i<ncpts ; i++ , j++ ) { for( int k=0 ; k<2 ; k++) // move next point i to point i-1 cpts[j][k]=cpts[i][k]; } ncpts--; } showList(); glutPostRedisplay(); drawElements(); glFlush(); } void mouse( int button , int state , int x , int y ) { float wx , wy ; // 把鼠标的位置逆向变换到世界坐标系 wx = (2.0*x)/ (float)(width-1) - 1.0 ; wy = (2.0 *(height -1-y) ) / (float)(height-1) -1.0; if( button==GLUT_RIGHT_BUTTON && state ==GLUT_DOWN ) { action_DeletePoint(wx , wy ); showList(); } if( button==GLUT_LEFT_BUTTON ) { switch( state ) { case GLUT_DOWN: action_LeftDown(wx , wy ); break; case GLUT_UP: action_LeftUp(); showList(); break; } } } void mouseMotion( int x , int y) { float wx = (2.0*x)/ (float)(width-1) - 1.0 ; float wy = (2.0 *(height -1-y) ) / (float)(height-1) -1.0; cpts[index][0] = wx ; cpts[index][1] = wy ; glutPostRedisplay(); drawElements(); glFlush(); } void keyboard(unsigned char key , int x , int y) { switch(key) { case 'q':case'Q': exit(0); break; case 'c':case'C': ncpts = 0 ; glutPostRedisplay(); glFlush(); break; case'e':case'E': glutPostRedisplay(); break; } } void reshape( int w , int h) { width = w ; height = h ; glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(-1.0 , 1.0 , -1.0 , 1.0 , -1.0 , 1.0 ); glMatrixMode(GL_MODELVIEW); glViewport(0 , 0 , w , h ); } int main(int argc , char **argv) { glutInit(&argc , argv); glutInitDisplayMode( GLUT_RGB ); glutInitWindowSize(width , height); glutCreateWindow("Bezier curves"); glutDisplayFunc(display); glutKeyboardFunc(keyboard); glutMouseFunc(mouse); glutMotionFunc(mouseMotion); glutReshapeFunc(reshape); glClearColor(1.0 , 1.0 , 1.0 , 1.0 ); glColor3f(0.0 , 0.0 , 0.0 ); glPointSize(5.0); glutMainLoop(); }