Simple tank shoot bullets

OpenGL OpenGL: Basic Coding
1

I am attempting to get a tank to shoot a bullet in a parabolic arc.

int i = 0;

int animate;

void vec_shoot()
{
	vector<float> move_sprite;

	for (float x = -14.0f; x <= 14.0f; x += 2.0f)
	{
		y = (-0.1f*(x*x)) + 20.0f;
		move_sprite.push_back(y);
	}

	y = move_sprite[i];
	x += 2.0f;
	if (x >= 30.0f)
	{
		x = 0.0f;
	}
	i++;
	if (i >= 15)
	{
		i = 0;
		animate = 0;
		glutIdleFunc(NULL);
	}
	glutPostRedisplay();
}
void handleKeypress(unsigned char key, int x, int y)
{
	switch (key)
	{
	case 27:
		exit(0);
		break;
	case 32:
		drawFireSprite();
		drawBulletSprite();
		animate = !animate;
		if (animate)
		{
			glutIdleFunc(vec_shoot);
		}
		else
		{
			glutIdleFunc(NULL);
		}
		glutSwapBuffers();
		break;