C++ Game Programming: New Book Learn C++ from scratch and start build your very own new games step by step by rizk zizo

Author:rizk, zizo [rizk, zizo]
Language: eng
Format: epub
Publisher: UNKNOWN
Published: 2021-12-24T00:00:00+00:00

Notice how the bullet fires neatly through the center of the crosshair. The way the shooting mechanic works is analogous to allowing the player to choose to shoot from the hip or aim down the sights. If the player keeps the crosshair close to the center, he can fire and turn rapidly, yet has to carefully judge the position of distant zombies.

Alternatively, the player can hover his crosshair directly over the head of a distant zombie and score a precise hit; however, he then has much further to move the crosshair back if a zombie attacks from another direction.

An interesting improvement to the game would be to add a small random amount of inaccuracy to each shot. This inaccuracy could perhaps be mitigated with an upgrade between waves.

Coding a class for pickups

We will code a Pickup class that has a Sprite, member as well as other member data and functions. We will add pickups to our game in just a few steps:

1. First, we will code the Pickup.h file. This will reveal all the details of the member data and the prototypes for the functions.

2. Then we will code the Pickup.cpp file which, of course, will contain the definitions for all the functions of the Pickup class. As we step

through it, I will explain exactly how an object of type Pickup will

work and be controlled.

3. Finally, we will use the Pickup class in the main function to spawn them, update them and draw them.

Let's get started with step 1.

Coding the Pickup header file

To make the new header file, right-click Header Files in the Solution Explorer and select Add | New Item... . In the Add New Item window, highlight (by left-clicking) Header File ( .h ) and then in the Name field

type Pickup.h .

Add and study the following code in the Pickup.h file and then we can go through it:

#pragma once

#include <SFML/Graphics.hpp>

using namespace sf;

class Pickup

{

private:

//Start value for health pickups const int HEALTH_START_VALUE = 50; const int AMMO_START_VALUE = 12; const int START_WAIT_TIME = 10; const int START_SECONDS_TO_LIVE = 5;

// The sprite that represents this pickup Sprite m_Sprite;

// The arena it exists in IntRect m_Arena;

// How much is this pickup worth? int m_Value;

// What type of pickup is this? // 1 = health, 2 = ammo

int m_Type;

float m_SecondsToWait;

// Handle spawning and disappearing bool m_Spawned;

float m_SecondsSinceSpawn;

float m_SecondsSinceDeSpawn; float m_SecondsToLive;

// Public prototypes go here };

The previous code declares all the private variables of the Pickup class. Although the names should be quite intuitive, it might not be obvious why many of them are needed at all. Let's go through them, starting from the top:

const int HEALTH_START_VALUE = 50 : This constant variable is used

to set the starting value of all health pickups. The value will be used to initialize the m_Value variable, which will need to be manipulated throughout the course of a game.

const int AMMO_START_VALUE = 12 : This constant variable is used to

set the starting value of all ammo pickups. The value will be used to initialize the m_Value variable, which will need to be manipulated throughout the course of a game.

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