固定盒2D图纸

Question

我试着画一个长方形，它的两边各有一条边（它应该代表一个有栅栏的建筑），对于一个建筑来说，它做得很好，但是当我试着添加一个新的建筑时，它把自己完全弄乱了。你知道吗

我有这个代码来创建建筑：

class Building():
    def __init__(self, Box_2_World,shape, position, sensor= None):
        self.Box_2_World = Box_2_World
        self.shape = shape
        self.position = position

        if sensor == None:
            sensor = False

        self.sensor = sensor
        self.footprint = self.Box_2_World.CreateStaticBody(position = position,
                                                           angle = 0.0,
                                                           fixtures = b2FixtureDef(
                                                               shape = b2PolygonShape(box=(self.shape)),
                                                               density = 1000,
                                                               friction = 1000))

        self.Lower_Fence = self.Box_2_World.CreateStaticBody(position=(self.footprint.position[0],self.footprint.position[1] -1.75*self.shape[1]))
        self.Lower_Fence.CreateEdgeChain([(self.Lower_Fence.position[0]-4.25*self.shape[0],self.Lower_Fence.position[1]),
                            (self.Lower_Fence.position[0]-2.25*self.shape[0],self.Lower_Fence.position[1]),
                        ])

        self.Right_Fence = self.Box_2_World.CreateStaticBody(position=(self.footprint.position[0]-1*self.shape[0],self.footprint.position[1]))
        self.Right_Fence.CreateEdgeChain([(self.Right_Fence.position[0],self.Right_Fence.position[1] - 1.25*self.shape[1]),
                            (self.Right_Fence.position[0],self.Right_Fence.position[1]-3.25*self.shape[1]),
                        ])

        self.Upper_Fence = self.Box_2_World.CreateStaticBody(position=(self.footprint.position[0],self.footprint.position[1] -0.45* self.shape[1]))
        self.Upper_Fence.CreateEdgeChain([(self.Upper_Fence.position[0] - 4.25* self.shape[0],self.Upper_Fence.position[1]),
                            (self.Upper_Fence.position[0]- 3.25* self.shape[0]+ self.shape[0],self.Upper_Fence.position[1]),
                        ])

        self.Left_Fence = self.Box_2_World.CreateStaticBody(position=(self.footprint.position[0]-2.25*self.shape[0],self.footprint.position[1]))
        self.Left_Fence.CreateEdgeChain([(self.Left_Fence.position[0],self.Left_Fence.position[1] - 1.25*self.shape[1]),
                            (self.Left_Fence.position[0],self.Left_Fence.position[1]-3*self.shape[1]),
                        ])

Skyscrapers = []
Rectangles = [(pos_X-5, pos_Y-5),(pos_X+15, pos_Y -5),(pos_X - 5,pos_Y + 15),(pos_X+15, pos_Y + 15)]

for i in range(4):
    Skyscrapers.append(Building(Box_2_World,shape = (5,5), position =  Rectangles[i]))

使用PyGame绘制的函数：

SCREEN_OFFSETX, SCREEN_OFFSETY = SCREEN_WIDTH/16, SCREEN_HEIGHT

def fix_vertices(vertices):
    return [(int(SCREEN_OFFSETX + v[0]), int(SCREEN_OFFSETY - v[1])) for v in vertices]
def _draw_polygon(polygon, screen, body, fixture):
    transform = body.transform
    vertices = fix_vertices([transform * v * PPM for v in polygon.vertices])
    pygame.draw.polygon(
        screen, [c / 2.0 for c in colors[body.type]], vertices, 0)
    pygame.draw.polygon(screen, colors[body.type], vertices, 1)
polygonShape.draw = _draw_polygon

def _draw_edge(edge, screen, body, fixture):
    vertices = fix_vertices(
        [body.transform * edge.vertex1 * PPM, body.transform * edge.vertex2 * PPM])
    pygame.draw.line(screen, colors[body.type], vertices[0], vertices[1])
edgeShape.draw = _draw_edge

结果是：蓝色的矩形代表建筑物，蓝色的线是栅栏，第一个建筑物很合适，但是其他的由于某种原因不符合要求

另外，如果您找到一种使用for loop创建fences的方法，那就太好了（这就是为什么我在这个问题中使用for loop标记的原因）

谢谢你的帮助

Answer 1

传递给CreateEdgeChain的坐标必须是相对于主体的。你知道吗

主体的位置是在构建对象时设置的，例如：

self.Lower_Fence = self.Box_2_World.CreateStaticBody(
    position=(self.footprint.position[0], self.footprint.position[1] -1.75*self.shape[1]))

边缘必须相对于这个位置，而不是绝对位置。例如：

self.Lower_Fence.CreateEdgeChain([(-4.25*self.shape[0], 0), (-2.25*self.shape[0], 0)])

要在for-循环中创建围栏，必须定义一个边列表。使用边列表，可以创建围栏列表：

fence_edges = [
    [(-4.25, -1.75), (-2.25, -1.75)],
    [(-1.00, -1.25), (-1.00, -3.25)],
    [(-4.25, -0.45), (-2.25, -0.45)],
    [(-2.25, -1.25), (-2.25, -3.25)]
]

self.Fences = []
for edge in fence_edges:
    p1, p2 = edge
    fence = self.Box_2_World.CreateStaticBody(position=self.footprint.position[:])
    fence.CreateEdgeChain(
        [(p1[0] * self.shape[0], p1[1] * self.shape[1]),
         (p2[0] * self.shape[0], p2[1] * self.shape[1])])
    self.Fences.append(fence)

self.Lower_Fence, self.Right_Fence, self.Upper_Fence, self.Left_Fence = self.Fences