Physics Basics for Games

Physics Basics for Games

Physics is one of the most important parts of game development. Physics makes movement feel natural smooth exciting and believable. Without physics games would feel stiff and unrealistic.

In Flutter web games using Flame Engine physics controls how objects move fall jump bounce fly float and react to forces.

Physics systems are used in almost every type of game:

Even simple games use basic physics systems. A jumping character a moving bullet or a bouncing ball all depend on physics calculations.

In this chapter you will learn the basic physics systems used in games including gravity jumping bullet physics speed systems bounce movement flying systems water movement floating systems suspension systems nitro boosts and trajectory calculations.

Understanding Gravity

Gravity is one of the most important physics systems in gaming. Gravity pulls objects downward and creates natural movement.

Without gravity characters would float forever after jumping. Gravity brings them back to the ground.

Most platform games use gravity systems continuously during gameplay.

Gravity works by increasing downward velocity every frame.

In simple game physics gravity is usually just a number added to vertical speed.

Here is a basic gravity example. 

class Player {

  double y = 300

  double velocityY = 0

  double gravity = 0.8

  void update() {

    velocityY += gravity

    y += velocityY

    if (y >= 300) {
      y = 300
      velocityY = 0
    }
  }
}

In this example gravity constantly pulls the player downward.

The ground position is set to 300. When the player reaches the ground falling stops.

Gravity strength changes gameplay feel. Weak gravity creates floaty movement while strong gravity creates fast heavy movement.

Different games use different gravity styles.

Gravity systems are important because they create believable motion and make movement feel alive.

Jump Physics

Jumping is one of the most common physics systems in gaming. Almost every platform game uses jump mechanics.

A jump works by giving the player upward velocity. Gravity then slowly pulls the player back down.

This creates a curved movement path called a jump arc.

Jump physics are extremely important because players instantly notice bad jumping systems.

Good jump controls feel responsive and smooth.

Here is a simple jump system. 

class PlayerCar {

  double y = 300

  double velocityY = 0

  double gravity = 0.8

  bool isJumping = false

  void jump() {

    if (!isJumping) {

      velocityY = -15

      isJumping = true
    }
  }

  void update() {

    velocityY += gravity

    y += velocityY

    if (y >= 300) {

      y = 300

      velocityY = 0

      isJumping = false
    }
  }
}

The jump starts by giving negative vertical velocity. Negative movement pushes the player upward.

Gravity then slowly reduces upward movement and eventually pulls the player downward again.

Different jump styles create different gameplay feelings.

Many games allow variable jump height. Holding the jump button longer creates a higher jump.

Platform games depend heavily on good jump physics because movement is the core gameplay mechanic.

Bullet Physics and Trajectory

Bullet physics control how projectiles move through the game world.

Some bullets move in straight lines while others follow curved paths using gravity and trajectory systems.

Trajectory means the path an object follows while moving.

In shooting games bullets often move forward continuously after being fired.

Here is a simple straight bullet system. 

class Bullet {

  double x
  double y

  double speed = 12

  Bullet(this.x, this.y)

  void update() {

    x += speed
  }
}

This bullet continuously moves right every frame.

Some games use realistic projectile movement where gravity affects bullets.

This creates curved movement called projectile trajectory. 

class CannonBall {

  double x = 100
  double y = 300

  double velocityX = 8
  double velocityY = -12

  double gravity = 0.5

  void update() {

    x += velocityX

    velocityY += gravity

    y += velocityY
  }
}

The cannon ball moves upward first then curves downward because of gravity.

Trajectory systems are used in:

Bullet physics make combat systems feel more realistic and exciting.

Speed and Acceleration

Speed controls how fast objects move in a game.

Acceleration controls how quickly speed changes.

Racing games platform games and flying games all depend heavily on speed systems.

Without acceleration movement feels robotic because objects instantly reach full speed.

Realistic movement usually increases speed gradually. 

class Car {

  double x = 100

  double speed = 0

  double acceleration = 0.2

  void update() {

    speed += acceleration

    x += speed
  }
}

The car slowly gains speed over time.

Friction can also reduce speed gradually. 

speed *= 0.98

This creates smoother movement and more natural controls.

Speed systems are important because they strongly affect gameplay pacing.

Fast movement creates excitement while slower movement creates precision gameplay.

Bounce Physics

Bounce systems make objects rebound after collisions.

Bounce physics are common in ball games physics puzzles arcade games and platform games.

A bounce usually happens by reversing velocity direction after collision.

Here is a simple bounce example. 

class Ball {

  double y = 100

  double velocityY = 8

  void update() {

    y += velocityY

    if (y >= 400) {

      velocityY = -velocityY
    }
  }
}

When the ball hits the ground the velocity reverses and the ball bounces upward.

Realistic bouncing usually loses energy after each bounce. 

velocityY = -velocityY * 0.7

The ball bounces lower each time because energy decreases.

Bounce systems create satisfying movement and realistic reactions.

Many physics based puzzle games depend heavily on bounce mechanics.

In Air Movement and Flying

Air movement controls how objects behave while not touching the ground.

Platform games often allow limited movement control while jumping.

Flying systems are similar but usually remove gravity restrictions.

Air movement affects gameplay feel greatly.

Tight air control creates responsive gameplay while loose control feels realistic.

Here is a simple flying system. 

class Bird {

  double x = 100
  double y = 100

  double speed = 5

  void flyUp() {
    y -= speed
  }

  void flyDown() {
    y += speed
  }
}

Flying systems are common in:

Some flying systems also include momentum and air resistance.

Air movement is important because it changes how players navigate the world.

Float and Water Physics

Water physics create slower and softer movement compared to normal gravity movement.

Objects inside water often fall slowly and float upward.

Water also creates resistance which slows movement.

Floating systems are useful for underwater games ocean games and survival games.

Here is a simple float system. 

class FloatingObject {

  double y = 300

  double floatSpeed = 1

  void update() {

    y -= floatSpeed
  }
}

This object slowly floats upward.

Water movement usually reduces gravity strength. 

gravity = 0.2

Reduced gravity creates softer underwater movement.

Water physics often feel calm and smooth compared to normal platform movement.

Many underwater games combine floating resistance and bubble effects together.

Nitro Boost Physics

Nitro boosts create sudden speed increases in racing games and action games.

Boost systems are exciting because they temporarily break normal movement limits.

A nitro boost usually increases acceleration and top speed for a short time.

Here is a simple nitro system. 

class RacingCar {

  double speed = 5

  bool nitroActive = false

  void activateNitro() {

    nitroActive = true

    speed = 15
  }

  void stopNitro() {

    nitroActive = false

    speed = 5
  }
}

Nitro boosts create fast exciting moments during gameplay.

Many racing games also add:

These effects make the boost feel more powerful.

Nitro systems are important because temporary speed changes create exciting gameplay variety.

Suspension Physics

Suspension systems are commonly used in vehicle games.

Suspension helps vehicles react naturally to bumps jumps and uneven terrain.

Without suspension vehicles would look stiff and unrealistic.

Suspension usually works like springs.

When the vehicle hits the ground the suspension compresses and then expands again.

Here is a simple suspension example. 

class SuspensionCar {

  double suspensionOffset = 0

  void hitBump() {

    suspensionOffset = 10
  }

  void update() {

    suspensionOffset *= 0.9
  }
}

The suspension moves upward after a bump and slowly returns to normal.

Suspension systems create smoother and more believable vehicle movement.

Racing games often combine suspension with tire physics and gravity systems.

Vehicle physics become much more realistic when suspension is included.

Conclusion

Physics systems are one of the foundations of game development. They create natural movement realistic reactions and exciting gameplay experiences.

Gravity controls falling movement. Jump systems create movement arcs. Bullet trajectory systems create projectile motion. Bounce systems create realistic rebounds. Flying and floating systems change movement behavior. Nitro boosts increase speed dramatically. Suspension systems improve vehicle realism.

Even simple physics systems can make games feel much more alive and professional.

Understanding game physics is important because movement and reactions strongly affect how players experience gameplay.

Once you master physics basics you can build platform games racing games flying games shooting games and physics puzzle games with much more realistic movement and interactions.

In the next chapter you will learn camera and world systems which control how players view and explore the game world.

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