Module 15 of 20 Phase: Intelligence & Camera

Building a Real Camera
Follow, Scroll, Shake & Parallax

Pygame has no built-in camera — you build one out of a single offset vector applied to everything you draw. This module covers following the player, smooth scrolling, zoom, screen shake, parallax backgrounds and mini-maps.

🎥

10 Lessons

This module

⏱

~2.5 hrs

Estimated time

📊

Intermediate

Difficulty

🐍

Offset vector

Core concept

Section 1

The Camera Offset Pattern

A 2D camera is nothing but an (x, y) offset subtracted from every world position before drawing. World objects never move — only the offset changes, creating the illusion of a scrolling world.

camera.py

class Camera:
    def __init__(self, width, height):
        self.offset = pygame.Vector2(0, 0)
        self.width = width
        self.height = height

    def apply(self, world_pos):
        return world_pos - self.offset

    def center_on(self, target_pos):
        self.offset.x = target_pos.x - self.width / 2
        self.offset.y = target_pos.y - self.height / 2

# in the draw loop:
screen.blit(player_img, camera.apply(player.pos))
screen.blit(enemy_img, camera.apply(enemy.pos))

Section 2

Following the Player & Smooth Scrolling

Snapping the camera exactly to the player every frame feels rigid. Instead, lerp the camera's offset toward the target position gradually, so it eases into place.

smooth_follow.py

def smooth_follow(self, target_pos, dt, smoothing=5.0):
    desired_x = target_pos.x - self.width / 2
    desired_y = target_pos.y - self.height / 2
    self.offset.x += (desired_x - self.offset.x) * smoothing * dt
    self.offset.y += (desired_y - self.offset.y) * smoothing * dt

Section 3

Zoom & Screen Shake

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Zoom

Render the world to a smaller off-screen Surface, then pygame.transform.scale() it up to fill the window — scaling up = zoom in, scaling down = zoom out.

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Screen Shake

Add a small random offset to the camera for a fixed duration after an impact — decaying in magnitude over the shake's lifetime.

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Mini-map

Draw every entity's position scaled down into a small corner Surface — same offset math, just a different scale factor.

screen_shake.py

import random

def trigger_shake(camera, duration=0.3, magnitude=8):
    camera.shake_timer = duration
    camera.shake_magnitude = magnitude

def update_shake(camera, dt):
    if camera.shake_timer > 0:
        camera.shake_timer -= dt
        camera.shake_offset = pygame.Vector2(
            random.uniform(-camera.shake_magnitude, camera.shake_magnitude),
            random.uniform(-camera.shake_magnitude, camera.shake_magnitude),
        )
    else:
        camera.shake_offset = pygame.Vector2(0, 0)

Section 4 · Parallax

Parallax Backgrounds

Parallax fakes depth by scrolling distant background layers SLOWER than the foreground — mimicking how distant mountains appear to move less than nearby trees as you travel.

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Key insight: Multiply the camera offset by a "depth factor" per layer (e.g. 0.2 for far mountains, 0.5 for mid-ground trees, 1.0 for the actual gameplay layer) before drawing each background layer.

parallax.py

layers = [
    {"img": mountains_img, "depth": 0.2},
    {"img": trees_img,     "depth": 0.5},
]

def draw_parallax(screen, camera, layers):
    for layer in layers:
        offset_x = -camera.offset.x * layer["depth"]
        screen.blit(layer["img"], (offset_x, 0))

Section 5

World Space vs. Screen Space

Every position in your game exists in two coordinate systems at once: world space, where objects have fixed, permanent coordinates, and screen space, the small visible window into that world. camera.offset is the translation between the two — subtract it from a world position and you get where that object should actually be drawn.

The Camera Viewport is a window into World space — camera.offset is the vector from the world's origin to that window's top-left corner.

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Building a Real CameraFollow, Scroll, Shake & Parallax