creating a cube with bouncing balls inside it [closed] - c++

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Closed 10 years ago.
i really want to draw a cube with balls bouncing on the walls of the cube but i can not get any further than this code below which is just a cube rotating im a newbie and i just started learning about opengl last week,if somebody can help me with the required info i will greatly appreciate,i want the ball to be bouncing upside down without them touching each other and thier radius should be the same
#include <GL\glut.h>
GLfloat xRotated, yRotated, zRotated;
void init(void)
{
glClearColor(0,0,0,0);
}
void DrawCube(void)
{
glMatrixMode(GL_MODELVIEW);
// clear the drawing buffer.
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glTranslatef(0.0,0.0,-10.5);
glRotatef(xRotated,1.0,0.0,0.0);
// rotation about Y axis
glRotatef(yRotated,0.0,1.0,0.0);
// rotation about Z axis
glRotatef(zRotated,0.0,0.0,1.0);
glBegin(GL_QUADS); // Draw The Cube Using quads
glColor3f(0.0f,1.0f,0.0f); // Color Blue
glVertex3f( 1.0f, 1.0f,-1.0f); // Top Right Of The Quad (Top)
glVertex3f(-1.0f, 1.0f,-1.0f); // Top Left Of The Quad (Top)
glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom Left Of The Quad (Top)
glVertex3f( 1.0f, 1.0f, 1.0f); // Bottom Right Of The Quad (Top)
glColor3f(1.0f,0.5f,0.0f); // Color Orange
glVertex3f( 1.0f,-1.0f, 1.0f); // Top Right Of The Quad (Bottom)
glVertex3f(-1.0f,-1.0f, 1.0f); // Top Left Of The Quad (Bottom)
glVertex3f(-1.0f,-1.0f,-1.0f); // Bottom Left Of The Quad (Bottom)
glVertex3f( 1.0f,-1.0f,-1.0f); // Bottom Right Of The Quad (Bottom)
glColor3f(1.0f,0.0f,0.0f); // Color Red
glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Quad (Front)
glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Quad (Front)
glVertex3f(-1.0f,-1.0f, 1.0f); // Bottom Left Of The Quad (Front)
glVertex3f( 1.0f,-1.0f, 1.0f); // Bottom Right Of The Quad (Front)
glColor3f(1.0f,1.0f,0.0f); // Color Yellow
glVertex3f( 1.0f,-1.0f,-1.0f); // Top Right Of The Quad (Back)
glVertex3f(-1.0f,-1.0f,-1.0f); // Top Left Of The Quad (Back)
glVertex3f(-1.0f, 1.0f,-1.0f); // Bottom Left Of The Quad (Back)
glVertex3f( 1.0f, 1.0f,-1.0f); // Bottom Right Of The Quad (Back)
glColor3f(0.0f,0.0f,1.0f); // Color Blue
glVertex3f(-1.0f, 1.0f, 1.0f); // Top Right Of The Quad (Left)
glVertex3f(-1.0f, 1.0f,-1.0f); // Top Left Of The Quad (Left)
glVertex3f(-1.0f,-1.0f,-1.0f); // Bottom Left Of The Quad (Left)
glVertex3f(-1.0f,-1.0f, 1.0f); // Bottom Right Of The Quad (Left)
glColor3f(1.0f,0.0f,1.0f); // Color Violet
glVertex3f( 1.0f, 1.0f,-1.0f); // Top Right Of The Quad (Right)
glVertex3f( 1.0f, 1.0f, 1.0f); // Top Left Of The Quad (Right)
glVertex3f( 1.0f,-1.0f, 1.0f); // Bottom Left Of The Quad (Right)
glVertex3f( 1.0f,-1.0f,-1.0f); // Bottom Right Of The Quad (Right)
glEnd(); // End Drawing The Cube
glFlush();
}
void animation(void)
{
yRotated += 0.01;
xRotated += 0.02;
DrawCube();
}
void reshape(int x, int y)
{
if (y == 0 || x == 0) return; //Nothing is visible then, so return
//Set a new projection matrix
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//Angle of view:40 degrees
//Near clipping plane distance: 0.5
//Far clipping plane distance: 20.0
gluPerspective(40.0,(GLdouble)x/(GLdouble)y,0.5,20.0);
glMatrixMode(GL_MODELVIEW);
glViewport(0,0,x,y); //Use the whole window for rendering
}
int main(int argc, char** argv){
glutInit(&argc, argv);
//we initizlilze the glut. functions
glutInitDisplayMode(GLUT_SINGLE|GLUT_RGB);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
init();
glutDisplayFunc(DrawCube);
glutReshapeFunc(reshape);
//Set the function for the animation.
glutIdleFunc(animation);
glutMainLoop();
return 0;
}

Answer 1

Introduce a ball object or at least a ball's position vector.
Let the drawing coordinates depend on the ball's position; since you have a cube now you'll need to find drawing code for a ball, you're not the first to do this so there are numerous examples to find on the internet.
Now, you change your animation function to move the ball in the direction you want it to go; a simple implementation is to let it go down and when it reaches the bottom you toggle a boolean which would indicate it goes up, then when it is a the top you toggle it again.
In pseudo-code we have something like this:
if (goingDown)
{
letBallGoDown();
if (ballTouchesBottom())
{
goingDown = false;
}
}
else
{
letBallGoUp();
if (ballTouchesTop())
{
goingDown = true;
}
}
Make sure you take radius into account when you are checking whether it touches top or bottom.