Membuat Objek Bergerak tanpa melakukan click and drag

Disini akan dijelaskan bagaimana mengubah posisi objek tanpa harus melakukan click and drag pada objek. Disini kita menggunakan fungsi glutPassiveMotionFunc(motion); untuk menggerakkan objek hanya dengan menggeser posisi pointer. Berikut adalah source code program:

#include "stdlib.h"

#include "stdio.h"

#include "glut.h"

int x=0,y=0,z=0,flag;

int w=480, h=480;

void drawQuad() {

      glBegin(GL_POLYGON);

      glColor3f(0,0,1);

            glVertex2f(-20.,-20.);

            glVertex2f(20.,-20.);

            glVertex2f(20.,20.); 

            glVertex2f(-20.,20.);

      glEnd();

}

void mouse(int button, int state, int xmouse, int ymouse){

      if(button==GLUT_LEFT_BUTTON && state==GLUT_UP)

      {

            x = xmouse-(w/2);

        y = (h/2)-ymouse;

        printf("x = %d\ny = %d \n",x,y);

            flag=1;

    }

      if(button==GLUT_RIGHT_BUTTON && state==GLUT_UP)

      {

            flag=0;

    }

     

}

void motion(int xmouse,int ymouse){

      if (flag==1)

      {

            x=xmouse-(w/2);

            y=(h/2)-ymouse;

            printf("x = %d\ny = %d \n",x,y);

      }

}

void renderScene(void){

      glClear(GL_COLOR_BUFFER_BIT);

      glClearColor(1,1,1,1);

      glPushMatrix();

        glTranslatef(x,y,z);

      drawQuad();

      glPopMatrix();

      glFlush();

}

void timer(int value){

      glutPostRedisplay();

      glutTimerFunc(50,timer,0);

}

void main (int argc, char **argv){

      glutInit(&argc, argv);

      glutInitWindowPosition(100,100);

      glutInitWindowSize(w,h);

      glutCreateWindow("Interaksi Mouse");

      gluOrtho2D(-w/2,w/2,-h/2,h/2);

      glutDisplayFunc(renderScene);

      glutMouseFunc(mouse);

        glutMotionFunc(motion);

        glutPassiveMotionFunc(motion);

      glutTimerFunc(1,timer,0);

      glutMainLoop();

}


Screenshot Program: