如何使用 pytmx 正确显示旋转对象？

Question

经过多次研究我没有找到答案，当我试图用 pytmx 在 pygame 中显示对象时，结果完全损坏，因为 x，y 随旋转而变化。我曾尝试使用矩阵旋转，但为此，我需要知道原始中心。不知道怎么找，因为Tiled在旋转后发给我，x,y...

所以我的目标只是用 pytmx 在 pygame 中显示对象图块。

import numpy
import math

angle = math.radians(-117.57) #rotation get with tiled, set - for cancel rotation
center_x = 148 #how to get this ?
center_y = 747 #and this
x = 126.82 #get with tiled
y = 679.54 #get with tiled

id_rotation = [ [math.cos(angle), -math.sin(angle)],
                [math.sin(angle), math.cos(angle)] ]
R = numpy.matrix(id_rotation)

id_position = [ [x - center_x],
                [y - center_y] ]
B = numpy.matrix(id_position)

id_center = [ [center_x],
              [center_y] ]
C = numpy.matrix(id_center)

print(numpy.dot(R, B) + C) #return original position before rotation

如果我只用pygame.transform.rotate:

if isinstance(layer, pytmx.TiledObjectGroup):
        for object in layer:
            if (object.image):
                assets_surface = pygame.Surface((object.width, object.height), pygame.SRCALPHA)
                assets_surface.blit(object.image, (0, 0))
                assets_surface_rotate = pygame.transform.rotate(assets_surface, -object.rotation)
                rdc.blit(assets_surface_rotate, (object.x, object.y))

我得到的图块对象的 x,y 位置错误：

Answer 1

我认为您在旋转后传递对象的 x 和 y 位置时犯了一些错误。我没用过tile map所以不知道具体情况，但是在pygame中把位置传给blit的时候应该传top-left角的坐标。 Surface 的 top-left 角将位于这些坐标处。

rdc.blit(assets_surface_rotate, (object.x, object.y))

这里我不知道坐标 object.x 和 object.y 是什么，但我敢打赌它们不是 top-left 角，或者你的代码应该可以工作。

一般来说，做这些工作你可以使用 Sprite class 或 subclass，这会有很大帮助。

class TMSprite(pygame.sprite.Sprite):
    # Constructor. Create a Surface from a TileMap and set its position
    def __init__(self, tmo, x, y, width, height):
        # Call the parent class (Sprite) constructor
        super(TMSprite, self).__init__()

        # Create the image of the block
        self.image = pygame.Surface((width, height), pygame.SRCALPHA)
        self.image.blit(tmo.image, (0, 0))

        # Fetch the rectangle object that has the dimensions of the image
        # Set its position with the move method
        self.rect = self.image.get_rect().move(x, y)

    def rotate(self, angle):
        # TMSprite rotation on its center of a given angle
        rot_center = self.rect.center
        self.image = pygame.transform.rotate(self.image, angle)
        self.rect = self.image.get_rect()
        self.rect.center = rot_center

这就是使用 TMSprite class.

重写代码片段的方法

if isinstance(layer, pytmx.TiledObjectGroup):
    for tmob in layer:
        if (tmob.image):
            x = tmob.x #x should be that of the top-left corner. Adjust the formula if tmob.x is not the top-left
            y = tmob.y #y should be that of the top-left corner. Adjust the formula if tmob.y is not the top-left
            assets_sprite = TMSprite(tmob, x, y, tmob.width, tmob.height)
            assets_sprite.rotate(-object.rotation)
            rdc.blit(assets_sprite.image, assets_sprite.rect)

在这里，我没有传递 top-left 坐标，而是将精灵的 Rect 传递给 blit。 blit 方法将从矩形中提取坐标。

请注意，旋转是在 Surface 的 centre 上执行的。旋转后，如果角度不是 90° 的倍数，则 Surface 会放大，因为 Surface 的正方形必须与屏幕对齐。如果有alpha通道没有问题，多余的像素是透明的，但是top-left角会变。

Answer 2

好的，如果有人需要，我已经找到了解决方案：

elif isinstance(layer, pytmx.TiledObjectGroup):
        for Object in layer:
            if (Object.image):
                if Object.rotation != 0:
                    angle = math.radians(-Object.rotation)
                    center_x = Object.centerX
                    center_y = Object.centerY
                    Object_y = Object.y + Object.height

                    id_rotation = [ [math.cos(angle), -math.sin(angle)],
                                    [math.sin(angle), math.cos(angle)] ]
                    R = numpy.matrix(id_rotation)

                    id_position = [ [Object.x - center_x],
                                    [Object_y - center_y] ]
                    P = numpy.matrix(id_position)

                    id_center = [ [center_x],
                                [center_y] ]
                    C = numpy.matrix(id_center)

                    position_without_rotation = numpy.dot(R, P) + C

                    no_rotation_x = position_without_rotation[0]
                    no_rotation_y = position_without_rotation[1] - Object.height #Repere Tiled pas le meme que Pygame

                    Object_surface = pygame.Surface((Object.image.get_rect()[2], Object.image.get_rect()[3]), pygame.SRCALPHA)
                    Object_surface.blit(Object.image, (0, 0))
                    Object_surface_scale = pygame.transform.scale(Object_surface, (round(Object.width), round(Object.height)))
                    Object_surface_rotate = pygame.transform.rotate(Object_surface_scale, -Object.rotation) #Pygame va en anti horaire

                    extra_x = (Object_surface_rotate.get_rect()[2] - Object.width) / 2
                    extra_y = (Object_surface_rotate.get_rect()[3] - Object.height) / 2

                    rdc.blit(Object_surface_rotate, (no_rotation_x - extra_x, no_rotation_y - extra_y))
                else:
                    Object_surface = pygame.Surface((Object.image.get_rect()[2], Object.image.get_rect()[3]), pygame.SRCALPHA)
                    Object_surface.blit(Object.image, (0, 0))
                    Object_surface_scale = pygame.transform.scale(Object_surface, (round(Object.width), round(Object.height)))

                    rdc.blit(Object_surface_scale, (Object.x, Object.y))

如何使用 pytmx 正确显示旋转对象？

How to correctly display rotation object with pytmx?

python

pygame

pytmx