[Pygame] Box2D 파이게임 물리 라이브러리

파이게임과 2D Rigid Body Simulation Library Box2D를 사용해 보자.

 

다음 명령어로 Box2D를 설치한다.

pip install box2d

 

설치중 에러가 발생한다면 SWIG를 설치하고 설치 디렉토리를 시스템 변수 Path에 등록한다.

SWIG

 

SWIG를 설치하면 에러가 발생하지 않는다.

 

추가로 box2d-kengz를 설치한다.

 

player.png

0.00MB

 

import math
import pygame
from Box2D import *
 
pygame.init()
pygame.display.set_caption("Physics Test")
screen = pygame.display.set_mode((640, 480))
running = True
player = pygame.image.load("player.png").convert()
 
# World 정의
world = b2World(gravity=(0, 9.8), doSleep=True)
 
# Ground 정의
groundBodyDef = b2BodyDef()
groundBodyDef.position = (0, 400)
groundBody = world.CreateBody(groundBodyDef)
groundShape = b2PolygonShape()
groundShape.SetAsBox(500, 0)
groundBody.CreateFixture(shape=groundShape)
#groundBody = world.CreateStaticBody(position=(0, 400), shapes=b2PolygonShape(box=(500, 0)))
# 위 정의와 동일
 
# Wall 정의
wallBodyDef = b2BodyDef()
wallBodyDef.position = (300, 0)
wallBody = world.CreateBody(wallBodyDef)
wallShape = b2PolygonShape()
wallShape.SetAsBox(0, 400)
wallBody.CreateFixture(shape=wallShape)
#wallBody = world.CreateStaticBody(position=(300, 0), shapes=b2PolygonShape(box=(0, 400)))
# 위 정의와 동일
 
# Player 정의
playerBodyDef = b2BodyDef()
playerBodyDef.type = b2_dynamicBody;
playerBodyDef.position = (0, 0)
playerBodyDef.linearVelocity = (50, 0)
playerBodyDef.angularVelocity = 0.2
playerBody = world.CreateBody(playerBodyDef)
playerShape = b2PolygonShape()
playerShape.SetAsBox(player.get_width()/2, player.get_height()/2)
playerFixtureDef = b2FixtureDef(shape=playerShape)
playerFixtureDef.density = 1
playerFixtureDef.friction = 0.5
playerFixtureDef.restitution = 0.7
playerBody.CreateFixture(playerFixtureDef)
#playerBody = world.CreateDynamicBody(position=(0, 0), linearVelocity=(50, 0),
#                                     angularVelocity=0.2)
#playerFixtureDef = playerBody.CreatePolygonFixture(box=(player.get_width()/2,
#                          player.get_height()/2), density=1, friction=0.5, restitution=0.7)
# 위 정의와 동일
 
timeStep = 1.0 / 300
vel_iters, pos_iters = 6, 2
  
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN and event.key == pygame.K_SPACE:
            playerBody.transform = ((0, 0), 0)
            playerBody.linearVelocity = (50, 0)
            playerBody.angularVelocity = 0.2
        elif event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE:
            running = False
    
    # Instruct the world to perform a single step of simulation. It is
    # generally best to keep the time step and iterations fixed.
    world.Step(timeStep, vel_iters, pos_iters)
    # Clear applied body forces. We didn't apply any forces, but you
    # should know about this function.
    world.ClearForces()
     
    screen.fill("white")
    pygame.draw.rect(screen, "brown", (0, 400, 600, 20)) # Ground 그리기
    pygame.draw.rect(screen, "black", (300, 0, 20, 400)) # Wall 그리기
 
    rotated_player = pygame.transform.rotate(player, playerBody.angle * 180/math.pi)
    # Unless rotating by 90 degree increments, the image will be padded larger to hold
    # the new size. If the image has pixel alphas, the padded area will be transparent.
    # Otherwise pygame will pick a color that matches the Surface colorkey or the topleft
    # pixel value.
    screen.blit(rotated_player, (playerBody.position[0] - rotated_player.get_width()/2,
                                 playerBody.position[1] - rotated_player.get_height()/2))
 
    pygame.display.flip()
    
pygame.quit()

 

코드를 입력하고 실행한다.

 

GIF 캡쳐 과정에서 화질이 많이 떨어졌지만 강체들의 물리 반응을 확인할 수 있다.

 

pygame.transform.rotate()

rotate an image
rotate(surface, angle) -> Surface

Unfiltered counterclockwise rotation. The angle argument represents degrees and can be any floating point value. Negative angle amounts will rotate clockwise.
Unless rotating by 90 degree increments, the image will be padded larger to hold the new size. If the image has pixel alphas, the padded area will be transparent. Otherwise pygame will pick a color that matches the Surface colorkey or the topleft pixel value.

 

배경을 바꾸거나 Colorkey를 설정하면 캐릭터 주변 패딩을 없앨 수 있다.

 

아래 링크에서 GUI를 구현해 본다.

2024.01.29 - [Python] - [Pygame] Pygame GUI 파이게임 그래픽 유저 인터페이스

 

※ 참고

PyBox2D

PyBox2D Manual