Introductions¶

Taxonomies 分类¶

By genre: action, adventure, role-playing, simulation, strategy, sports, puzzle, idle, etc.
By platform: PC, console, mobile, VR, etc.
By purpose: entertainment, education, training, marketing, etc.
By controller: touchscreens, motion capture, gamepads, keyboards, etc.

Pygame¶

Modules¶

Game Loop¶

intro1.py

pygame.init()

size = width, height = 1024, 768
speed = [3,2]
black = (0, 0, 0)

screen = pygame.display.set_mode(size)
pygame.display.set_caption('Logo Bouncer')
logo = pygame.image.load(logo_file)
logo_width, logo_height = logo.get_size()
logo_x = logo_y = 0

running = True
clock = pygame.time.Clock()
while running:
    clock.tick(30)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    logo_x += speed[0]
    logo_y += speed[1]

    if logo_x < 0 or logo_x + logo_width > width:
        speed[0] = -speed[0]
    if logo_y < 0 or logo_y + logo_height > height:
        speed[1] = -speed[1]

    screen.fill(black)
    screen.blit(logo, (logo_x, logo_y))
    pygame.display.flip()

The structure of intro1.py:

some initialization stuff
a game loop: Game ends when loop is exited

game loop:

check for updates (from user input, network, etc.)
update game state
draw the next frame

Frame¶

One picture is rendered (calculated and shown to user) each time around the loop.

FPS: frames per second

Event Queue¶

# Example event processing
def get_inputs():
    done = left = right = False
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            done = True
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                done = True
            elif event.key == pygame.K_RIGHT:
                right = True
            elif event.key == pygame.K_LEFT:
                left = True
    return (left, right, done)

一次 game loop 中，可能有多个事件，如键盘按键、鼠标点击等，需要逐个处理。

MVC: model-view-controller¶

Model¶

Manages the data and operations on the data.

Provides a well-defined interface to the data.

View¶

Provides a way to visualize the data: Draw the frame, make the music, etc.

Controller¶

Maps input actions to model or view actions.

Object-oriented model/view 面向对象¶

Each object knows its own state, so is part of the model.

Each object knows how to draw itself, so is part of the view. have a draw method.

Graphic Primitives 图形基元¶

An engine provides some level of graphic algorithms to be embedded in your code. Pygame is an engine for 2D games.

Each pixel has a color. Usually formed by mixing 8-bit values for red, green, blue and alpha.

In Python and Pygame, the color is a tuple or a hex string.

Red = (255, 0, 0)
Red = '0xFF0000'

Alpha Channel¶

An extra 8-bits specifies the amount of transparency.

0 = transparent. 完全透明
255 = opaque. 完全不透明

The Surface¶

In Pygame, a surface is a place to draw.

Special surface: the display surface -- will be visible to the user in the game window.

display_surface = pygame.display.set_mode((800, 600))

Other surfaces can be created and drawn on the display surface.

background = pygame.Surface(display_surface.get_size())
display_surface.blit(background, (0, 0))

Surface Operations¶

get_at, set_at: get or set the color of a pixel

color = background.get_at((100, 100))
background.set_at((100, 100), color)

- fill: fill the surface with a color

background.fill((255, 255, 255))

- And a line can be drawn between two points with pygame.draw.line.

pygame.draw.line(surface, color, (x0, y0), (x1, y1))

Draw module¶

pygame.draw.arc: draw an elliptical or circular arc from start_angle to stop_angle (in radians)
```
pygame.draw.arc(surface, color, rect, start_angle, stop_angle, width)
```
Position and dimensions are specified by the rect parameter, a bounding box. 位置和尺寸由 rect 参数指定，在一个边界框内。
pygame.draw.lines: draw a series of connected lines
```
pygame.draw.lines(surface, color, closed, pointlist, width)
```
If closed is True, will also connect the last point back to the first.
pygame.draw.polygon: draw a polygon
```
pygame.draw.polygon(surface, color, pointlist)
```
polygon acts similarly, connecting points from a list, but then it fills in the enclosed space.

与 lines 设置 closed 参数为 True 类似，polygon 会自动连接最后一个点和第一个点。若未设置 width 参数，则会填充多边形。
pygame.draw.circle: draw a circle
```
pygame.draw.circle(surface, color, center, radius)
```
与 polygon 类似，circle 会填充圆形。

Rect¶

Rects are defined by four values.

rect = pygame.Rect(x, y, width, height)

Rect Methods¶

copy: return a new rect with the same values
move: return a new rect moved by a given offset
move_ip: move the rect by a given offset
inflate: return a new rect with the size changed by a given amount
clip: return a new rect that is the intersection of two rects
union: return a new rect that is the union of two rects
contains: check if a rect is completely inside another
collidepoint: check if a point is inside the rect
colliderect: check if two rects overlap
collidelist: check if a rect overlaps with any in a list

Draw¶

pygame.draw.rect: draw a rectangle
```
pygame.draw.rect(surface, color, rect, width)
```
If width is 0, the rectangle will be filled.
pygame.draw.ellipse: draw an ellipse. 矩形的内切椭圆
```
pygame.draw.ellipse(surface, color, rect, width)
```
If width is 0, the ellipse will be filled.

Images and Blit¶

Image Load / Save¶

pygame.image.load: load an image from a file
```
surface = pygame.image.load(filename)
```
- pygame.image.save: save an image to a file
```
pygame.image.save(surface, filename)
```
- pygame.surface.convert: convert a surface to a new format
```
new_surface = surface.convert()
```
convert will change the format of a surface to match the display surface.

BLIT¶

BLIT "pastes" one image into another.

The Surface object has a blit method for pasting another image (or portion) into the image

surface.blit(source, dest, area=None, special_flags=0)

source: the surface to be pasted
dest: the position to paste the source
area: can be a rect to paste only a portion of the source, only the area that intersects with the rect in the source will be pasted
special_flags: can be used to control the pasting

Colorkey¶

Colorkey is a special color that is ignored when blitting.

surface.set_colorkey(color)

Surface Transforms¶

pygame.transform module has methods to manipulate a surface. rotate / scale / chop / greyscale / ...