OpenGL鼠标旋转图像

#include <iostream>
using namespace std;

#include<gl/glut.h>

GLfloat transx,transy;

GLfloat scale;

int primw=300;
int primh=300;

GLfloat rotatex=0,rotatey=0;

GLint mousepx,mousepy;

void rend(void)
{
    glClear(GL_COLOR_BUFFER_BIT);
    glPointSize(8);
    glLineWidth(2);
    glColor3f(1,0,0);

    glPushMatrix();
    glTranslatef(transx,transy,0);
    glRotatef(rotatex,1,0,0);
    glRotatef(rotatey,0,1,0);
    glBegin(GL_LINES);
        glVertex3f(0,0,0);
        glVertex3f(0,2,0);
        glVertex3f(0,0,0);
        glVertex3f(2,0,0);
        glVertex3f(0,0,0);
        glVertex3f(0,0,2);
    glEnd();
    glBegin(GL_LINES);
        glVertex3f(0,0,0);
        glVertex3f(10,6,0);
        glVertex3f(10,10,0);
    glEnd();
    glPopMatrix();

        
    glFlush();
}

void reshape(int w, int h)
{
    glViewport(0,0,w,h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if(w<=h)
        gluOrtho2D(-10,10,-10.0/w*h,10.0/w*h);
    else
        gluOrtho2D(-10.0/h*w,10.0/h*w,-10,10);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    
    if(w<=h)
    {
    /*    scale=(GLfloat)primw/w;*/
        transx=(50-w/2.0)*20.0/w;
        transy=(50-h/2.0)*20.0/w;
    }
    else
    {
/*        scale=(GLfloat)primh/h;*/
        transx=(50-w/2.0)*20.0/h;
        transy=(50-h/2.0)*20.0/h;
    }

}

void motion(int x, int y)
{    
    int w,h;
    w=glutGet(GLUT_WINDOW_WIDTH);
    h=glutGet(GLUT_WINDOW_HEIGHT);

    if(0<=x && x<=w && 0<=y && y<=h)
    {
        rotatex=(mousepy-y)/(GLfloat)h*360;
        rotatey=(mousepx-x)/(GLfloat)w*360;
/*        cout<<"rotatex:rotatey"<<rotatex<<" "<<rotatey<<endl;*/
        glutPostRedisplay();
    }

}

void mousedown(int mouse, int state , int x, int y)
{
    if(state== GLUT_DOWN)
    {
        mousepx=x;
        mousepy=y;
    }
//     cout<<"mousepx:mousepy"<<endl;
//     cout<<mousepx<<"  "<<mousepy<<endl;
}

int main(int argc,char** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode(GLUT_RGB);
    glutInitWindowSize(primw,primh);
    glutCreateWindow("coordination");

    glClearColor(1,1,1,0);
    glutDisplayFunc(rend);
    glutMotionFunc(motion);
    glutMouseFunc(mousedown);
    glutReshapeFunc(reshape);
    glutMainLoop();

    return 0;
}