openGLの視点についての質問

openGLのアニメーションを勉強しています。
下のプログラムのどこを変更したら、表示視点が変わりますか？　
回答よろしくお願い致します。

#include <stdlib.h>
#include "GL/glut.h"
#include <GL/gl.h>
#include <GL/glu.h>
#include <math.h>
#define KEY_ESC 27
#define PAI 3.1415926536

void polarview(void);
void resetview(void);
unsigned char revolveFlag = GL_FALSE;
unsigned char wireFlag =GL_TRUE;
float xOrig = 0.0,yOrig = 0.0;

float rColor = 1.0, gColor = 1.0, bColor = 1.0;

int xBegin,yBegin;
int mButton;
float distance,twist,elevation,azimuth;

float dist=0.0;
float theta =15.0;

void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
polarview();
glTranslatef(xOrig,yOrig,-10.0);

glColor3f(rColor,gColor,bColor);

if(wireFlag == GL_TRUE)
	glutWireSphere(1.0,15,15); 
else
	glutSolidSphere(1.0,15,15); 

glPopMatrix();
glutSwapBuffers();

}

void idle(void)
{
theta = fmod(theta+0.5,360.);
glutPostRedisplay();
}

void changeColor(void)

rColor= (float)rand()/RAND_MAX;/*R成分*/
gColor= (float)rand()/RAND_MAX;/*R成分*/
bColor= (float)rand()/RAND_MAX;/*R成分*/

}

void myKbd(unsigned char key, int x, int y)
{
switch(key){
case 'w':
wireFlag = !wireFlag;/
break;
case 'R':
changeColor();
break;
case KEY_ESC:
exit(0);
default:
rColor=1.0;
gColor=1.0;
bColor=1.0;
}
glutPostRedisplay();
}

void myMouse(int button,int state,int x,int y)
{
if(state == GLUT_DOWN){
switch(button){
case GLUT_LEFT_BUTTON:
mButton = button;
break;

	case GLUT_RIGHT_BUTTON:
		mButton = button;
		break;
	}
	xBegin = x; 
	yBegin = y;
}

}

void myMotion( int x, int y)
{
int xDisp, yDisp;

xDisp = x- xBegin;
yDisp = y -yBegin;

switch(mButton){
case GLUT_LEFT_BUTTON:
	distance +=(float)yDisp/40.0;
	break;
}
xBegin = x;
yBegin = y;
glutPostRedisplay();

}

void mySkey(int key,int x, int y)
{
switch(key){
case GLUT_KEY_LEFT:/左矢印キー/

		xOrig -=0.2;
		if( xOrig <= -2.0) xOrig =-2.0;
		break;
	case GLUT_KEY_RIGHT:/*右矢印キー*/
		xOrig +=0.2;
		if( xOrig >= 2.0) xOrig =2.0;
		break;
	case GLUT_KEY_UP:/*上矢印キー*/
		yOrig +=0.1;
		if( yOrig>= 2.0) yOrig =2.0;
		break;
	case GLUT_KEY_DOWN:/*下矢印キー*/
		yOrig -=0.2;
		if( y<= -2.0) yOrig =-2.0;
		break;
}
glutPostRedisplay();

}

void myInit(char *progname)
{
int width=600, height=600;
float aspect =(float)width/(float)height;
glutInitWindowPosition(0,0);
glutInitWindowSize(width,height);
glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA);
glutCreateWindow(progname);
glClearColor(0.0,0.0,0.0,1.0);

glutKeyboardFunc(myKbd);
glutSpecialFunc(mySkey);
glutMouseFunc(myMouse);
glutMotionFunc(myMotion);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(30.0,aspect,1.0,20.0);
glMatrixMode(GL_MODELVIEW);

}

void resetview(void)
{
distance =5.0;
twist = 0.0;
elevation = 0.0;
azimuth = 0.0;
}

void polarview(void)
{
glTranslatef(0.0,0.0,-distance);
glRotatef(-twist,0.0,0.0,1.0);
glRotatef(-elevation,1.0,0.0,0.0);
glRotatef(-azimuth,0.0,1.0,0.0);
}

int main(int argc, char** argv)
{
glutInit(&argc,argv);
myInit(argv[0]);
glutDisplayFunc(display);
glutIdleFunc(NULL);
glutMainLoop();
return(0);
}