#include <stdlib.h>
#include <time.h>
#include <GL/glut.h>
GLfloat ctrlpoints[4][4][3] = {
{ { -1.5, -1.5, 2.0 },
{ -0.5, -1.5, 2.0 },
{ 0.5, -1.5, -1.0 },
{ 1.5, -1.5, 2.0 } },
{ { -1.5, -0.5, 1.0 },
{ -0.5, 1.5, 2.0 },
{ 0.5, 0.5, 1.0 },
{ 1.5, -0.5, -1.0 } },
{ { -1.5, 0.5, 2.0 },
{ -0.5, 0.5, 1.0 },
{ 0.5, 0.5, 3.0 },
{ 1.5, -1.5, 1.5 } },
{ { -1.5, 1.5, -2.0 },
{ -0.5, 1.5, -2.0 },
{ 0.5, 0.5, 1.0 },
{ 1.5, 1.5, -1.0 } } };
GLUnurbsObj *pNurb;
void init(void)
{
//背景色
glClearColor(0.0, 0.0, 0.0, 1.0);
//代码开关3：设置材质与光源
GLfloat ambient[] = { 0.4, 0.6, 0.2, 1.0 };
GLfloat position[] = { 1.0, 1.0, 3.0, 1.0 };
GLfloat mat_diffuse[] = { 0.8, 0.6, 0.3, 1.0 };
GLfloat mat_specular[] = { 0.8, 0.6, 0.3, 1.0 };
GLfloat mat_shininess[] = { 45.0 };
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_AMBIENT, ambient);
glLightfv(GL_LIGHT0, GL_POSITION, position);
glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess);
//允许深度测试
glDepthFunc(GL_LESS);
glEnable(GL_DEPTH_TEST);
//代码开关4：取消下面两行代码，查看曲面显示效果差异
//打开自动法矢量开关
glEnable(GL_AUTO_NORMAL);
//允许正则化法矢量
glEnable(GL_NORMALIZE);
pNurb = gluNewNurbsRenderer(); // 创建一个NURBS曲面对象
//修改NURBS曲面对象的属性——glu库函数
////采样sampling容错torerance
gluNurbsProperty(pNurb, GLU_SAMPLING_TOLERANCE, 5.0);
gluNurbsProperty(pNurb, GLU_DISPLAY_MODE, GLU_FILL);
}
void display(void)
{
GLfloat knots[8]={0.0,0.0,0.0,0.0,1.0,1.0,1.0,1.0}; //控制向量
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(0.0, 1.0, 0.0);
glLineWidth(1.0f);
gluNurbsProperty(pNurb,GLU_SAMPLING_TOLERANCE,25.0); //设置属性
gluNurbsProperty(pNurb,GLU_DISPLAY_MODE, GLU_OUTLINE_POLYGON);
glRotatef(1.0, 0.7, -0.6, 1.0); // 旋转变换
gluBeginSurface(pNurb); // 开始曲面绘制
//网络查询：参数GL_MAP2_VERTEX_3的作用？
//将
gluNurbsSurface(pNurb, 8, knots, 8, knots, 4 * 3, 3, &ctrlpoints[0][0][0], 4, 4, GL_MAP2_VERTEX_3); // 定义曲面的数学模型，确定其形状
gluEndSurface(pNurb); // 结束曲面绘制
glutSwapBuffers();
}
void reshape(GLsizei w, GLsizei h)
{
glViewport(0, 0, w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
if (w <= h)
glOrtho(-5.0, 5.0, -5.0*(GLfloat)h / (GLfloat)w, 5.0*(GLfloat)h / (GLfloat)w, -5.0, 5.0);
else
glOrtho(-5.0*(GLfloat)w / (GLfloat)h, 5.0*(GLfloat)w / (GLfloat)h, -5.0, 5.0, -5.0, 5.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
void keyboard(unsigned char key, int x, int y)
{
switch (key)
{
case 'x':
case 'X':
case 27: //ESC键
exit(0);
break;
default:
break;
}
}
int main(int argc, char** argv)
{
srand((unsigned int)time(0));
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);//使用双缓存模式和深度缓存
glutInitWindowSize(800, 800);
glutInitWindowPosition(0, 0);
glutCreateWindow("Bezier曲面");
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutIdleFunc(display);//设置空闲时调用的函数
glutMainLoop();
return 0;
}
