李兴球Python像素级碰撞检测理论与实践图

"""
   移动B图去碰撞A图并且画重叠区域.py
   本程序演示了像素极碰撞的基本理论。   
"""
__author__ = '李兴球'
__date__ = '2020/10/15'
__blog__ = 'www.lixingqiu.com'

import numpy as np
from rect import Rect
from gameturtle import *

def make_croped_area(overlaped,rectangle):
    """返回将要剪裁的区域
       overlaped:Rect对象，相对于画布坐标系的
       rectangle:Rect对象，也是相对于画布坐标系的
       返回left,top,right,bottom，相对于rectangle的
    """
    left = overlaped.left - rectangle.left
    top = overlaped.top - rectangle.top
    right = left + overlaped.width
    bottom = top + overlaped.height
    return left,top,right,bottom

def make_mask(image,area):
    """
       image:pillow图形对象
       area:图形对象上的一个区域
    """
    im = image.crop(area)
    im_array = np.array(im)
    mask = im_array[:,:,3] > 127
    mask.dtype=np.uint8
    return mask,im
    
def draw_rect(r):
    if r:      # 如果重叠了
        v.clear()
        v.goto(r.left,r.top)
        v.pendown()
        for _ in range(2):
            v.fd(r.width)
            v.rt(90)
            v.fd(r.height)
            v.rt(90)
        v.penup()
    else:
        v.clear()
        
root = Tk()
root.title('像素级碰撞理论示意原理图')

cv = Canvas(width=480,height=480,bg='#98f9f9')
cv.pack()

dot = GameTurtle(cv,Image.new("RGBA",(5,5),color='red'))

v = GameTurtle(cv,Image.new("RGBA",(1,1)))
a_pic = GameTurtle(cv,Image.open('a.png'))
a_pic.rect = Rect(140,140,200,200)
b_pic = GameTurtle(cv,Image.open('b.png'))

cv.tag_raise(dot.item)               # 升起来

while True:
    mx,my = b_pic.mouse_pos()
   
    b_pic.goto(mx,my)
    b_pic.rect = Rect(mx-100,my-75,200,150)
    r = b_pic.rect.overlap(a_pic.rect)
    if r:       
       draw_rect(r)
       r_a = make_croped_area(r,a_pic.rect)    # 返回在a图上的待剪区域
       r_b = make_croped_area(r,b_pic.rect)    # 返回在b图上的待剪区域

       # mask_a是重叠区域的alpha通道0,1化后的描述透明与不透明区域的二维数组
       # im_a是在a图上剪下来的图形
       mask_a,im_a = make_mask(a_pic._current_shape,r_a)  # 剪后形成mask_a
       mask_b,im_b = make_mask(b_pic._current_shape,r_b)
       mask = mask_a  + mask_b
       array = np.argwhere(mask == 2)          # 所有碰撞点的行列号
       if array.size > 0:
          top,left = array[0]                  # 第一个点的行列号
          y,x = int(top) + r.top,int(left) + r.left # 相对于画布的坐标
          dot.goto(x,y)                   # 红点到此

          p1 = im_a.getpixel((int(left),int(top)))
          p2 = im_b.getpixel((int(left),int(top)))
          s = str(x) + ',' + str(y) + ', 在a图上的像素值' + str(p1)
          s = s + ', 在b图上的像素值' + str(p2)
          root.title(s)# 显示碰撞点坐标
    else:
        root.title("")
        v.clear()
          
    
    cv.update()