Rect Collision Response
Rect Collision Response
This is a simple demo on how to do side-based rectangle collision response. It's extremely simple, and not very hard to understand.
ConceptI'm putting this here since it's not in the download. Basically how it works is when you move a rect, you first move along the X axis, test for a collision, move out, then move along the Y axis, test for a collision, and move out. This prevents the infamous "corner-catching" bug, and lets you move smoothly along walls.
#! /usr/bin/env python import os import random import pygame # Class for the orange dude class Player(object): def __init__(self): self.rect = pygame.Rect(32, 32, 16, 16) def move(self, dx, dy): # Move each axis separately. Note that this checks for collisions both times. if dx != 0: self.move_single_axis(dx, 0) if dy != 0: self.move_single_axis(0, dy) def move_single_axis(self, dx, dy): # Move the rect self.rect.x += dx self.rect.y += dy # If you collide with a wall, move out based on velocity for wall in walls: if self.rect.colliderect(wall.rect): if dx > 0: # Moving right; Hit the left side of the wall self.rect.right = wall.rect.left if dx < 0: # Moving left; Hit the right side of the wall self.rect.left = wall.rect.right if dy > 0: # Moving down; Hit the top side of the wall self.rect.bottom = wall.rect.top if dy < 0: # Moving up; Hit the bottom side of the wall self.rect.top = wall.rect.bottom # Nice class to hold a wall rect class Wall(object): def __init__(self, pos): walls.append(self) self.rect = pygame.Rect(pos, pos, 16, 16) # Initialise pygame os.environ["SDL_VIDEO_CENTERED"] = "1" pygame.init() # Set up the display pygame.display.set_caption("Get to the red square!") screen = pygame.display.set_mode((320, 240)) clock = pygame.time.Clock() walls =  # List to hold the walls player = Player() # Create the player # Holds the level layout in a list of strings. level = [ "WWWWWWWWWWWWWWWWWWWW", "W W", "W WWWWWW W", "W WWWW W W", "W W WWWW W", "W WWW WWWW W", "W W W W W", "W W W WWW WW", "W WWW WWW W W W", "W W W W W W", "WWW W WWWWW W W", "W W WW W", "W W WWWW WWW W", "W W E W W", "WWWWWWWWWWWWWWWWWWWW", ] # Parse the level string above. W = wall, E = exit x = y = 0 for row in level: for col in row: if col == "W": Wall((x, y)) if col == "E": end_rect = pygame.Rect(x, y, 16, 16) x += 16 y += 16 x = 0 running = True while running: clock.tick(60) for e in pygame.event.get(): if e.type == pygame.QUIT: running = False if e.type == pygame.KEYDOWN and e.key == pygame.K_ESCAPE: running = False # Move the player if an arrow key is pressed key = pygame.key.get_pressed() if key[pygame.K_LEFT]: player.move(-2, 0) if key[pygame.K_RIGHT]: player.move(2, 0) if key[pygame.K_UP]: player.move(0, -2) if key[pygame.K_DOWN]: player.move(0, 2) # Just added this to make it slightly fun ;) if player.rect.colliderect(end_rect): raise SystemExit, "You win!" # Draw the scene screen.fill((0, 0, 0)) for wall in walls: pygame.draw.rect(screen, (255, 255, 255), wall.rect) pygame.draw.rect(screen, (255, 0, 0), end_rect) pygame.draw.rect(screen, (255, 200, 0), player.rect) pygame.display.flip()
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