其他计算机图形学实验见 链接

#include<gl/glut.h>
#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
const float window_width = 800, window_height = 600;
const int d = 8;
const int maxn = 99999;struct point
{float x, y;point() {}point(float xx, float yy):x(xx), y(yy) {}
};
vector<point> input_vertice;
vector<point> control_point;char OP;
int k = 3;
float controlpoint_color[3] = { 1,0,0 };
float straightline_color[3] = { 0,1,0 };
float Bspline_color[3] = { 0,0,1 };float N[5];void draw_a_point(float x, float y, float color[]);
void deBoor();
void mymouse(int button, int state, int x, int y);
void dragmouse(int x, int y);
void keyboard(unsigned char key, int x, int y);
int getdis(int x, int y);//获取离得最近的点int main(int argc, char* argv[])
{glutInit(&argc, argv);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);glutInitWindowPosition(50, 50);glutInitWindowSize(window_width, window_height);glutCreateWindow("de Boor 绘制B样条曲线");cout << "点击键盘数字2-4切换阶数" << endl;cout << "不做操作则默认k=3，如需输入其他阶数，请按k后输入阶数" << endl;cout << "键盘点击p后，点击鼠标左键绘制控制点" << endl;cout << "键盘点击i后，插入控制点" << endl;cout << "键盘点击d后，移动控制点" << endl;cout << "键盘点击e后，点击鼠标左键删除控制点" << endl;cout << "按ESC退出" << endl << endl;glMatrixMode(GL_PROJECTION);glLoadIdentity();gluOrtho2D(0, window_width, 0, window_height);glClearColor(1, 1, 1, 1);glClear(GL_COLOR_BUFFER_BIT);glutMouseFunc(&mymouse);glutMotionFunc(&dragmouse);glutKeyboardFunc(&keyboard);glutMainLoop();return 0;
}void draw_a_point(float x, float y, float color[])
{glPointSize(3.0f);glBegin(GL_POINTS);glColor3fv(color);glVertex2f(x, y);glEnd();glFlush();
}int getdis(int x, int y)
{int ans = -1;float shortdis = 99999999;for (int i = 0; i < input_vertice.size(); i++){float dis = sqrt(pow(x - input_vertice[i].x, 2) + pow(y - input_vertice[i].y, 2));if (dis < shortdis && dis <= d){shortdis = dis;ans = i;}}return ans;
}int index1 = -1;
void mymouse(int button, int state, int x, int y)
{if (OP == 'p')//绘制控制点{if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN){int index = getdis(x, window_height - y);if (index == -1)//鼠标范围内没有控制点，新加操作点{draw_a_point(x, window_height - y, controlpoint_color);point p(x, window_height - y);input_vertice.push_back(p);cout << "新输入的控制点" << input_vertice.size() << ":(" << x << ", " << window_height - y << ")" << endl;}/*glBegin(GL_LINE_STRIP);glColor3fv(straightline_color);for (int i = 0; i < input_vertice.size(); i++)glVertex2f(input_vertice[i].x, input_vertice[i].y);glEnd();glFlush();*/control_point = input_vertice;deBoor();}}if (OP == 'i')//插入控制点{if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN){index1 = getdis(x, window_height - y);cout << "将插入新的控制点到 选中的控制点" << index1 << "前" << endl;}if (button == GLUT_LEFT_BUTTON && state == GLUT_UP && index1 != -1){input_vertice.insert(input_vertice.begin() + index1, point(x, window_height - y));//在下标pos前插入一个元素//deBoor();}control_point = input_vertice;deBoor();}if (OP == 'e'){if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN)//删除控制点{int index = getdis(x, window_height - y);cout << "删除点" << index << " ";if (index != -1)//鼠标范围内有控制点了，可以删除，否则不做操作{vector<point>::iterator it = input_vertice.begin();cout << (*(it + index)).x << " " << (*(it + index)).y << endl;input_vertice.erase(it + index);}elsecout << "没有可以删除的点" << endl;control_point = input_vertice;deBoor();}}
}void dragmouse(int x, int y)
{int index = getdis(x, window_height - y);if (OP == 'd' && index != -1)//鼠标范围内有控制点了，可以拖动{//cout << "修改控制点" << input_vertice.size() << ":(" << input_vertice[index].x << ", " << input_vertice[index].y << ")" << endl;input_vertice[index].x = x;input_vertice[index].y = window_height - y;control_point = input_vertice;//deBoor();glClear(GL_COLOR_BUFFER_BIT);//绘制控制点for (int i = 0; i < input_vertice.size(); i++)draw_a_point(input_vertice[i].x, input_vertice[i].y, controlpoint_color);//绘制多边形glLineWidth(2.0f);glBegin(GL_LINE_STRIP);glColor3fv(straightline_color);for (int i = 0; i < input_vertice.size(); i++)glVertex2f(input_vertice[i].x, input_vertice[i].y);glEnd();glFlush();deBoor();}
}void keyboard(unsigned char key, int x, int y)
{if (key == 27)exit(0);if (key == 'p')//画点{OP = 'p';cout << "当前阶数为" << k << endl;cout << "请点击鼠标左键，开始绘制控制点以及B样条曲线" << endl;}if (key == 'd')//拖动端点{OP = 'd';cout << "请按住端点拖动" << endl;}if (key == 'i')//插入控制点{OP = 'i';cout << "请点击一个已有的控制点按住不放，松开位置为新插入顶点的位置。新插入的顶点位于点击的顶点之前。 " << endl;}if (key == 'e'){OP = 'e';cout << "鼠标左键点击要删除的点" << endl;}if (key == '2'){k = 2;cout << "修改阶数为2，重新绘制B样条曲线" << endl;deBoor();}if (key == '3'){k = 3;cout << "修改阶数为3，重新绘制B样条曲线" << endl;deBoor();}if (key == '4'){k = 4;cout << "修改阶数为4，重新绘制B样条曲线" << endl;deBoor();}if (key == 'k'){cout << "修改阶数为：" << endl;cin >> k;cout << "重新绘制B样条曲线" << endl;deBoor();}
}void deBoor()
{vector<point> b_spline;int n = control_point.size() - 1;//cout <<"control_point_size-1=" << n << endl;float t[maxn];//均匀B样条/*for (int i = 0; i <= input_vertice.size() + k; i++)t[i] = i + 1;*///准均匀B样条t[0] = 0; for (int i = 0; i <= k - 1; i++)t[i] = 0;for (int i = k; i < n + 1; i++)t[i] = t[i - 1] + 1.0 / (n + 1 - k + 1);for (int i = n + 1; i <= n + k; i++)t[i] = 1;for (int j = k - 1; j <= n; j++)//j为区间的末端点{for (double u = t[j]; u <= t[j + 1]; u += 0.001 / n){for (int r = 1; r <= k - 1; r++)//递推k-1层{for (int i = j; i >= j - k + r + 1; i--)//由递推公式得，需要倒着来，i和i-1存在i中；；bezier为j和j+1存在j中{float x1 = u - t[i];float x2 = t[i + k - r] - t[i];float y1 = t[i + k - r] - u;float y2 = t[i + k - r] - t[i];float coefficient1, coefficient2;if (x1 == 0.0 && x2 == 0.0)coefficient1 = 0;elsecoefficient1 = x1 / x2;if (y1 == 0.0 && y2 == 0.0)coefficient2 = 0;elsecoefficient2 = y1 / y2;if (r == 1)//第一轮必须是输入的那几个控制点{control_point[i].x = input_vertice[i].x * coefficient1 + input_vertice[i - 1].x * coefficient2;control_point[i].y = input_vertice[i].y * coefficient1 + input_vertice[i - 1].y * coefficient2;continue;}else{control_point[i].x = control_point[i].x * coefficient1 + control_point[i - 1].x * coefficient2;control_point[i].y = control_point[i].y * coefficient1 + control_point[i - 1].y * coefficient2;}}}b_spline.push_back(control_point[j]);//递推的最后一层的点，即为求得的点}}//cout << "BSpline size = :" << b_spline.size() << endl;glClear(GL_COLOR_BUFFER_BIT);//清空屏幕上上一次的曲线//绘制控制点for (int i = 0; i < input_vertice.size(); i++)draw_a_point(input_vertice[i].x, input_vertice[i].y, controlpoint_color);//绘制控制多边形glBegin(GL_LINE_STRIP);glColor3fv(straightline_color);for (int i = 0; i < input_vertice.size(); i++)glVertex2f(input_vertice[i].x, input_vertice[i].y);glEnd();glFlush();//画出b_spline曲线glLineWidth(3.0f);glBegin(GL_LINE_STRIP);glColor3fv(Bspline_color);for (int i = 0; i < b_spline.size(); i++)glVertex2f(b_spline[i].x, b_spline[i].y);glEnd();glFlush();
}