opengl通过三次bezier曲线绘制花瓶

要使用OpenGL通过三次Bezier曲线绘制花瓶，可以按照以下步骤进行：

1. 定义Bezier曲线的控制点，一般需要四个点来定义一个曲线段。

2. 使用OpenGL的顶点缓冲对象(VBO)将Bezier曲线的控制点数据存储到显存中。

3. 定义花瓶的材质属性，例如表面颜色、反射率等。

4. 使用OpenGL的着色器程序(Shader)进行渲染，可以通过编写顶点着色器和片元着色器来控制花瓶的渲染效果。

5. 在OpenGL的渲染循环中，使用glDrawArrays或glDrawElements命令来将Bezier曲线渲染到屏幕上。

以下是一个简单的OpenGL通过三次Bezier曲线绘制花瓶的代码示例：

// 定义Bezier曲线的控制点
GLfloat controlPoints[] = {
    // 花瓶底部曲线
    -0.5f, -1.0f, 0.0f,
    -0.25f, -0.75f, 0.0f,
    0.25f, -0.75f, 0.0f,
    0.5f, -1.0f, 0.0f,
    // 花瓶侧面曲线
    0.5f, -1.0f, 0.0f,
    0.5f, 1.0f, 0.0f,
    0.25f, 1.0f, 0.0f,
    0.0f, 0.9f, 0.0f,
    -0.25f, 1.0f, 0.0f,
    -0.5f, 1.0f, 0.0f,
    -0.5f, -1.0f, 0.0f,
};

// 计算Bezier曲线上的点
glm::vec3 calculateBezierPoint(GLfloat t, glm::vec3 p0, glm::vec3 p1, glm::vec3 p2, glm::vec3 p3)
{
    GLfloat u = 1.0f - t;
    GLfloat tt = t * t;
    GLfloat uu = u * u;
    GLfloat uuu = uu * u;
    GLfloat ttt = tt * t;

    glm::vec3 p = uuu * p0;
    p += 3.0f * uu * t * p1;
    p += 3.0f * u * tt * p2;
    p += ttt * p3;

    return p;
}

// 定义顶点着色器代码
const char* vertexShaderCode = R"(
    #version 330 core

    layout (location = 0) in vec3 bezierPoint;
    layout (location = 1) in vec3 aColor;

    out vec3 vertexColor;

    void main()
    {
        gl_Position = vec4(bezierPoint, 1.0);
        vertexColor = aColor;
    }
)";

// 定义片元着色器代码
const char* fragmentShaderCode = R"(
    #version 330 core

    in vec3 vertexColor;

    out vec4 FragColor;

    void main()
    {
        FragColor = vec4(vertexColor, 1.0);
    }
)";

int main()
{
    // 初始化OpenGL窗口和上下文

    // 创建和绑定VBO
    GLuint VBO;
    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(controlPoints), controlPoints, GL_STATIC_DRAW);

    // 定义顶点着色器和片元着色器
    GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertexShader, 1, &vertexShaderCode, NULL);
    glCompileShader(vertexShader);

    GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragmentShader, 1, &fragmentShaderCode, NULL);
    glCompileShader(fragmentShader);

    // 创建着色器程序
    GLuint shaderProgram = glCreateProgram();
    glAttachShader(shaderProgram, vertexShader);
    glAttachShader(shaderProgram, fragmentShader);
    glLinkProgram(shaderProgram);

    // 使用着色器程序进行渲染
    glUseProgram(shaderProgram);

    // 获取顶点位置和颜色属性
    GLint bezierPointAttrib = glGetAttribLocation(shaderProgram, "bezierPoint");
    glVertexAttribPointer(bezierPointAttrib, 3, GL_FLOAT, GL_FALSE, 0, 0);
    glEnableVertexAttribArray(bezierPointAttrib);

    GLint colorAttrib = glGetAttribLocation(shaderProgram, "aColor");
    glVertexAttribPointer(colorAttrib, 3, GL_FLOAT, GL_FALSE, 0, colors);
    glEnableVertexAttribArray(colorAttrib);

    // 开始渲染循环
    while (!glfwWindowShouldClose(window))
    {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // 绘制花瓶
        for (int i = 0; i < 2; i++)
        {
            glBegin(GL_LINE_STRIP);
            for (GLfloat t = 0.0f; t <= 1.0f; t += 0.01f)
            {
                glm::vec3 p0 = glm::vec3(controlPoints[i * 4], controlPoints[i * 4 + 1], controlPoints[i * 4 + 2]);
                glm::vec3 p1 = glm::vec3(controlPoints[i * 4 + 1 * 3], controlPoints[i * 4 + 1 * 3 + 1], controlPoints[i * 4 + 1 * 3 + 2]);
                glm::vec3 p2 = glm::vec3(controlPoints[i * 4 + 2 * 3], controlPoints[i * 4 + 2 * 3 + 1], controlPoints[i * 4 + 2 * 3 + 2]);
                glm::vec3 p3 = glm::vec3(controlPoints[i * 4 + 3 * 3], controlPoints[i * 4 + 3 * 3 + 1], controlPoints[i * 4 + 3 * 3 + 2]);

                glm::vec3 curvePoint = calculateBezierPoint(t, p0, p1, p2, p3);
                glColor3f(1.0f, 1.0f, 1.0f);
                glVertex3f(curvePoint.x, curvePoint.y, curvePoint.z);
            }
            glEnd();
        }

        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    // 清理资源
    glDeleteShader(vertexShader);
    glDeleteShader(fragmentShader);
    glDeleteProgram(shaderProgram);
    glDeleteBuffers(1, &VBO);

    glfwTerminate();
    return 0;
}