Moving sprites, in a hex grid

I have drawn a hex grid and a sprite; I want to move the sprite to move from hex to hex.

void drawHex()
{
	const float hexagon_r = 10.0;
	const float hexagon_dx = hexagon_r * cos(30.0*PI / 180.0);
	const float hexagon_dy = hexagon_r * sin(30.0*PI / 180.0);
	const float hexagon_gx = 2.0*hexagon_dx;
	const float hexagon_gy = 2.0*hexagon_dx*sin(60.0*PI / 180.0);
	float x = 1.0f, y = 1.0f, z = 0.0f;
	int ni = 22, nj = 22;
			int i, j; float x0;
			x -= float(ni - 1)*hexagon_gx*0.5; // just shift x,y to start position (i=0,j=0)
			x -= float(nj - 1)*hexagon_dx*0.5;
			y -= float(nj - 1)*hexagon_gy*0.5;
			for (x0 = x, j = 0; j < nj; j++, x0 += hexagon_dx, x = x0, y += hexagon_gy)
			{
				for (i = 0; i < ni; i++, x += hexagon_gx)
				{
					glBegin(GL_LINE_LOOP);
					glVertex3f(x - hexagon_dx, y - hexagon_dy, z);
					glVertex3f(x - hexagon_dx, y + hexagon_dy, z);
					glVertex3f(x, y + hexagon_r, z);
					glVertex3f(x + hexagon_dx, y + hexagon_dy, z);
					glVertex3f(x + hexagon_dx, y - hexagon_dy, z);
					glVertex3f(x, y - hexagon_r, z);
					glEnd();
				}
			}
}

void drawTankNorthWest()
{
	glEnable(GL_TEXTURE_2D);
	glBindTexture(GL_TEXTURE_2D, texture[0]);
	glBegin(GL_QUADS);
	
	glTexCoord2f(0.0f, 0.0f);
	glVertex2f(0.0f + move_x, -5.0f + move_y);
	
	glTexCoord2f(1.0f, 0.0f);
	glVertex2f(5.0f + move_x, 0.0f + move_y);
	
	glTexCoord2f(1.0f, 1.0f);
	glVertex2f(0.0f + move_x, 5.0f + move_y);
	
	glTexCoord2f(0.0f, 1.0f);
	glVertex2f(-5.0f + move_x, 0.0f + move_y);
	
	glEnd();
	glDisable(GL_TEXTURE_2D);
}