GLfloat ctlpoints[4][4][3]; // 控制点的存储空间
GLUnurbsObj *theNurb; // 指向NURBS曲面对象的指针
void InitSurface()
{
int u, v;
for (u = 0; u < 4; u++) {
for (v = 0; v < 4; v++) {
ctlpoints[u][v][0] = 2.0 * ((GLfloat)u - 1.5);
ctlpoints[u][v][1] = 2.0 * ((GLfloat)v - 1.5);
if ((u == 1 || u == 2) && (v == 1 || v == 2)) ctlpoints[u][v][2] = 6;
else ctlpoints[u][v][2] = -6;
}
}
}
void Init(void)
{
GLfloat mat_diffuse[] = {0.8, 0.6, 0.3, 1.0}; // 定义曲面材质
GLfloat mat_specular[] = {0.8, 0.6, 0.3, 1.0};
GLfloat mat_shininess[] = {45.0};
glClearColor(0.0, 0.0, 0.0, 1.0);
glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glDepthFunc(GL_LESS);
glEnable(GL_DEPTH_TEST);
glEnable(GL_AUTO_NORMAL);
glEnable(GL_NORMALIZE);
InitSurface(); // 初始化控制点
theNurb = gluNewNurbsRenderer(); // 创建一个NURBS曲面对象
// 修改NURBS曲面对象的属性
gluNurbsProperty(theNurb, GLU_SAMPLING_TOLERANCE, 5.0);
gluNurbsProperty(theNurb, GLU_DISPLAY_MODE, GLU_FILL);
}
void CALLBACK Display()
{
GLfloat knots[8] = {0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0}; // NURBS曲面的控制向量
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // 清屏
glPushMatrix(); // 入栈
glRotatef(30.0, -1.0, 0.0, 0.0); // 旋转变换
glScalef (0.5, 0.5, 0.5); // 缩放变换
gluBeginSurface(theNurb); // 开始曲面绘制
gluNurbsSurface(theNurb, 8, knots, 8, knots, 4 * 3, 3, &ctlpoints[0][0][0], 4, 4, GL_MAP2_VERTEX_3); // 定义曲面的数学模型,确定其形状
gluEndSurface(theNurb); // 结束曲面绘制
glPopMatrix(); // 出栈
glFlush(); // 强制刷新
}