# 第三章：遊戲物件初始設定
## 磚塊
* ### 定義磚塊類別
* #### 介紹：
* 初始建構：
* 將圖像設成寬為`BRICK_WIDTH`、高為`BRICK_HEIGHT`、顏色為紅色的矩形。
* 將左上角位置設在傳入的`(x, y)`座標
* #### 程式碼：
```python=
class Brick(pygame.sprite.Sprite):
def __init__(self, x, y):
super().__init__()
self.image = pygame.Surface((BRICK_WIDTH, BRICK_HEIGHT))
self.image.fill(RED)
self.rect = self.image.get_rect()
self.rect.topleft = x, y
```
* ### 相關常數設定
* #### 介紹：
* #### 程式碼：
```python=
BRICK_ROWS = 5
BRICK_COLS = 8
BRICK_MARGIN = 70
BRICK_SPACING = 8
BRICK_WIDTH = (WIDTH - 2 * BRICK_MARGIN - (BRICK_COLS - 1) * BRICK_SPACING) // BRICK_COLS
BRICK_HEIGHT = 45
```
* ### 創建物件
```python=
# 磚塊 Group
bricks = pygame.sprite.Group()
# 迴圈創建磚塊
for r in range(BRICK_ROWS):
for c in range(BRICK_COLS):
x = c * (BRICK_WIDTH + BRICK_SPACING) + BRICK_MARGIN
y = r * (BRICK_HEIGHT + BRICK_SPACING) + BRICK_MARGIN
brick = Brick(x, y)
all_sprites.add(brick)
bricks.add(brick)
```
## 板子
* ### 定義板子類別
* #### 介紹：
* 初始建構：
* 將圖像設為大小為`BOARD_SIZE`、顏色為藍色的矩形
* 將中心位置設在傳入的`center`座標
* 移動速度（每步移動距離）設為 15
* 每次`update()`時若按住
* 左鍵：向左移動一步，若圖形左側超出視窗左側，將其移回視窗左側
* 右鍵：向右移動一步，若圖形右側超出視窗右側，將其移回視窗右側
* #### 程式碼：
```python=
BOARD_SIZE = (150, 30)
class Board(pygame.sprite.Sprite):
def __init__(self, center):
super().__init__()
self.image = pygame.Surface(BOARD_SIZE)
self.image.fill(BLUE)
self.rect = self.image.get_rect()
self.rect.center = center
self.speed = 15
def update(self):
keys = pygame.key.get_pressed()
if keys[pygame.K_LEFT]:
self.rect.x -= self.speed
if self.rect.left < 0:
self.rect.left = 0
if keys[pygame.K_RIGHT]:
self.rect.x += self.speed
if self.rect.right > WIDTH:
self.rect.right = WIDTH
```
* #### 語法說明：
* `pygame.key.get_pressed()`：
用來偵測鍵盤上哪些按鍵正被按住。回傳一個「*boolean* 的列表」，表示每個按鍵的狀態（按下是 True，沒按是 False）。
* `pygame.K_LEFT` / `pygame.K_RIGHT`：
用以表示鍵盤某個按鍵的 *int* 常數，拿來和鍵盤事件做比對或查詢。分別表示左鍵和右鍵。
* ### 創建物件
```python=
board = Board((WIDTH // 2, HEIGHT - 60))
all_sprites.add(board)
```
## 球
* ### 定義球類別
* #### 介紹：
* 設定「全部球」的移動速度。
* 初始建構：
* 將圖像設定為半徑為`BALL_RADIUS`、顏色為綠色的「圓形」
* 將中心位置設在傳入的`center`座標
* 利用球速以及傳入的移動角度`angle`，透過三角函數算出 x , y 方向的速度
* 每次`update`：
* 向前移動一步
* 如果撞到上、左或右的便反彈
* 如果掉到底下則將其刪除
* #### 程式碼：
```python=
import math
BALL_RADIUS = 15
class Ball(pygame.sprite.Sprite):
speed = 7
def __init__(self, angle, center):
super().__init__()
self.image = pygame.Surface((2 * BALL_RADIUS, 2 * BALL_RADIUS), pygame.SRCALPHA)
pygame.draw.circle(self.image, GREEN, (BALL_RADIUS, BALL_RADIUS), BALL_RADIUS)
self.rect = self.image.get_rect()
self.rect.center = center
self.dx = Ball.speed * math.sin(angle)
self.dy = -Ball.speed * math.cos(angle)
def update(self):
self.rect.x += self.dx
self.rect.y += self.dy
if self.rect.left <= 0:
self.rect.left = 0
self.dx = -self.dx
elif self.rect.right >= WIDTH:
self.rect.right = WIDTH
self.dx = -self.dx
if self.rect.top <= 0:
self.rect.top = 0
self.dy = -self.dy
elif self.rect.top >= HEIGHT:
self.kill()
```
:::info
須先導入 `math` 模組
:::
* #### 語法說明：
* `pygame.SRCALPHA`
Pygame 中的一個旗標常數（flag constant），代表啟用透明度的功能。原先預設只有 (R, G, B) 三個通道，使用後變成 (R, G, B, A) 四個通道，A 表示透明度。
* `pygame.draw.circle(surface, color, center, radius)`
在平面上畫一個圓形。surface為選擇的平面，color為圓形顏色，center為圓心在平面上的位置，radius為圓形半徑。
* ### 創建物件
```python=
balls = pygame.sprite.Group()
ball = Ball(math.pi / 4, (WIDTH // 2, HEIGHT - 150))
all_sprites.add(ball)
balls.add(ball)
```
---
:::spoiler 完整程式碼
```python=
import pygame
import math
FPS = 60
# 大小設定
WIDTH, HEIGHT = 800, 700
BRICK_ROWS = 5
BRICK_COLS = 8
BRICK_MARGIN = 70
BRICK_SPACING = 8
BRICK_WIDTH = (WIDTH - 2 * BRICK_MARGIN - (BRICK_COLS - 1) * BRICK_SPACING) // BRICK_COLS
BRICK_HEIGHT = 40
BOARD_SIZE = (150, 30)
BALL_RADIUS = 15
# 顏色設定
WHITE = (255, 255, 255)
BLUE = (0, 0, 255)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("打磚塊遊戲")
clock = pygame.time.Clock()
# 定義磚塊類別
class Brick(pygame.sprite.Sprite):
def __init__(self, x, y):
super().__init__()
self.image = pygame.Surface((BRICK_WIDTH, BRICK_HEIGHT))
self.image.fill(RED)
self.rect = self.image.get_rect()
self.rect.topleft = x, y
# 定義板子類別
class Board(pygame.sprite.Sprite):
def __init__(self, center):
super().__init__()
self.image = pygame.Surface(BOARD_SIZE)
self.image.fill(BLUE)
self.rect = self.image.get_rect()
self.rect.center = center
self.speed = 15
def update(self):
keys = pygame.key.get_pressed()
if keys[pygame.K_LEFT]:
self.rect.x -= self.speed
if self.rect.left < 0:
self.rect.left = 0
if keys[pygame.K_RIGHT]:
self.rect.x += self.speed
if self.rect.right > WIDTH:
self.rect.right = WIDTH
class Ball(pygame.sprite.Sprite):
speed = 7
def __init__(self, angle, center):
super().__init__()
self.image = pygame.Surface((2 * BALL_RADIUS, 2 * BALL_RADIUS), pygame.SRCALPHA)
pygame.draw.circle(self.image, GREEN, (BALL_RADIUS, BALL_RADIUS), BALL_RADIUS)
self.rect = self.image.get_rect()
self.rect.center = center
self.dx = Ball.speed * math.sin(angle)
self.dy = -Ball.speed * math.cos(angle)
def update(self):
self.rect.x += self.dx
self.rect.y += self.dy
if self.rect.left <= 0:
self.rect.left = 0
self.dx = -self.dx
elif self.rect.right >= WIDTH:
self.rect.right = WIDTH
self.dx = -self.dx
if self.rect.top <= 0:
self.rect.top = 0
self.dy = -self.dy
elif self.rect.top >= HEIGHT:
self.kill()
all_sprites = pygame.sprite.Group()
# 磚塊
bricks = pygame.sprite.Group()
for r in range(BRICK_ROWS):
for c in range(BRICK_COLS):
x = c * (BRICK_WIDTH + BRICK_SPACING) + BRICK_MARGIN
y = r * (BRICK_HEIGHT + BRICK_SPACING) + BRICK_MARGIN
brick = Brick(x, y)
all_sprites.add(brick)
bricks.add(brick)
# 板子
board = Board((WIDTH // 2, HEIGHT - 60))
all_sprites.add(board)
# 球
balls = pygame.sprite.Group()
ball = Ball(math.pi / 4, (WIDTH // 2, HEIGHT - 150))
all_sprites.add(ball)
balls.add(ball)
running = True
while running:
clock.tick(FPS)
# 輸入處理
for event in pygame.event.get():
if event.type == pygame.QUIT:
running = False
# 更新遊戲
all_sprites.update()
# 畫面顯示
screen.fill(WHITE)
all_sprites.draw(screen)
pygame.display.update()
pygame.quit()
```
:::
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