c++和opengl实现生成B样条曲线代码

下面是一个简单的 C++ 和 OpenGL 实现生成 B 样条曲线的代码示例：

#include <GL/glut.h>
#include <vector>

using namespace std;

const int WINDOW_WIDTH = 600;
const int WINDOW_HEIGHT = 600;

vector<pair<float, float>> controlPoints; // 控制点数组
vector<pair<float, float>> splinePoints; // 样条曲线点数组

int degree = 3; // B 样条曲线的次数
int segments = 32; // 曲线的线段数

// 计算 B 样条基函数
float Bspline(int i, int k, float t) {
    if (k == 1) {
        if (t >= controlPoints[i].first && t < controlPoints[i + 1].first) {
            return 1.0f;
        } else {
            return 0.0f;
        }
    } else {
        float w1 = 0.0f, w2 = 0.0f;
        if (controlPoints[i + k - 1].first != controlPoints[i].first) {
            w1 = (t - controlPoints[i].first) / (controlPoints[i + k - 1].first - controlPoints[i].first);
        }
        if (controlPoints[i + k].first != controlPoints[i + 1].first) {
            w2 = (controlPoints[i + k].first - t) / (controlPoints[i + k].first - controlPoints[i + 1].first);
        }
        return w1 * Bspline(i, k - 1, t) + w2 * Bspline(i + 1, k - 1, t);
    }
}

// 计算 B 样条曲线上的点
void calculateSplinePoints() {
    splinePoints.clear();
    if (controlPoints.size() < degree + 1) {
        return;
    }
    for (int i = 0; i <= segments; i++) {
        float t = controlPoints[degree].first + (controlPoints[controlPoints.size() - degree - 1].first - controlPoints[degree].first) * i / segments;
        float x = 0.0f, y = 0.0f;
        for (int j = 0; j < controlPoints.size(); j++) {
            float b = Bspline(j, degree, t);
            x += controlPoints[j].second * b;
            y += controlPoints[j].first * b;
        }
        splinePoints.push_back(make_pair(y, x));
    }
}

// 绘制 B 样条曲线
void drawSpline() {
    glBegin(GL_LINE_STRIP);
    for (int i = 0; i < splinePoints.size(); i++) {
        glVertex2f(splinePoints[i].second, splinePoints[i].first);
    }
    glEnd();
}

// 绘制控制点
void drawControlPoints() {
    glPointSize(5.0f);
    glBegin(GL_POINTS);
    for (int i = 0; i < controlPoints.size(); i++) {
        glVertex2f(controlPoints[i].second, controlPoints[i].first);
    }
    glEnd();
}

// 鼠标事件处理函数
void onMouse(int button, int state, int x, int y) {
    if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
        controlPoints.push_back(make_pair(WINDOW_HEIGHT - y, x));
        calculateSplinePoints();
        glutPostRedisplay();
    }
}

// 渲染函数
void render() {
    glClear(GL_COLOR_BUFFER_BIT);
    glColor3f(1.0f, 1.0f, 1.0f);
    drawSpline();
    glColor3f(1.0f, 0.0f, 0.0f);
    drawControlPoints();
    glutSwapBuffers();
}

// 初始化函数
void initialize() {
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluOrtho2D(0, WINDOW_WIDTH, 0, WINDOW_HEIGHT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}

int main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowSize(WINDOW_WIDTH, WINDOW_HEIGHT);
    glutCreateWindow("B-spline Curve");
    initialize();
    glutDisplayFunc(render);
    glutMouseFunc(onMouse);
    glutMainLoop();
    return 0;
}

这段代码使用了 GLUT 库来创建窗口和处理鼠标事件，计算 B 样条曲线上的点，并在 OpenGL 中绘制出 B 样条曲线和控制点。你可以根据自己的需要修改代码来适配不同的场景。