opengl学习笔记（五）:组合变换，绘制一个简单的太阳系

创建太阳系模型

描述的程序绘制一个简单的太阳系，其中有一颗行星和一颗太阳，用同一个函数绘制。需要使用glRotate*()函数让这颗行星绕太阳旋转，并且绕自身的轴旋转。还需要使用glTranslate*()函数让这颗行星离开原点，移动到它自己的轨道上。可以在glutWireSphere()函数中使用适当的参数，在绘制球体时指定球体的大小。

planet.c

#include <GL/glut.h>

static int year =,day =;

void init(void)

{

    glClearColor(0.0,0.0,0.0,0.0);

    glShadeModel(GL_FLAT);

}

void display(void)

{

    glClear(GL_COLOR_BUFFER_BIT);

    glColor3f(1.0,1.0,1.0);

    glPushMatrix();

    glutSolidSphere(1.0,,);

    glRotatef((GLfloat)year,0.0,1.0,0.0);

    glTranslatef(2.0,0.0,0.0);

    glRotatef((GLfloat)day,0.0,1.0,0.0);

    glutSolidSphere(0.2,,);

    glPopMatrix();

    glutSwapBuffers();

}

void reshape(int w, int h)

{

    glViewport(,,(GLsizei)w,(GLsizei)h);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    gluPerspective(60.0,(GLfloat)w/(GLfloat)h,1.0,20.0);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

    gluLookAt(0.0,0.0,5.0,0.0,0.0,0.0,0.0,1.0,0.0);

}

void keyboard(unsigned char key, int x, int y)

{

    switch (key){

        case 'd':

        day =(day + )%;

        glutPostRedisplay();

        break;

        case 'D':

        day =(day - )%;

        glutPostRedisplay();

        break;

        case 'y':

        year =(year +  )%;

        glutPostRedisplay();

        break;

        case 'Y':

        year =(year - )%;

        glutPostRedisplay();

        break;

        default:

        break;

    }

}

int main(int argc, char** argv)

{

    glutInit(&argc,argv);

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);

    glutInitWindowSize(,);

    glutInitWindowPosition(,);

    glutCreateWindow(argv[]);

    init();

    glutDisplayFunc(display);

    glutReshapeFunc(reshape);

    glutKeyboardFunc(keyboard);

    glutMainLoop();

    return ;

}

在终端gcc生成可执行程序

gcc planet.c -o planet -lGL -lGLU -lglut

执行程序

./planet

程序运行效果如下所示

d和D建行星自转

y和Y控制行星围绕太阳进行旋转

巴特西

opengl学习笔记（五）:组合变换，绘制一个简单的太阳系

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