在化工厂处理过程中如何正确地绘制框？
在化工厂处理过程中如何正确地绘制框？
提问于 2016-03-18 23:52:27
我试图用pyprocessing编写一个非常基本的框绘制程序，但是当逻辑看起来正常时，检查鼠标是否在框内的条件失败：
#!/usr/bin/env python
from pyprocessing import *
S = 20
W = 5
H = 5
data = [[0] * W] * H
def setup():
size(W*(S+5),H*(S+5))
def draw():
background(0)
for y in xrange(H):
for x in xrange(W):
fill(data[x][y] * 255)
rect(x*S,y*S,S,S)
def mouseDragged():
for y in xrange(H):
for x in xrange(W):
xs = x * S
ys = y * S
# this doesn't behave as expected: it should draw a single box if the condition is met, not the whole row
if (mouse.x >= xs) and (mouse.x <= (xs+S)) and (mouse.y >= ys and mouse.y <= (ys+S)):
if key.pressed:
data[x][y] = 0
else:
data[x][y] = 1
run()我尝试了使用正在处理中的Java的相同方法，它的工作原理与预期的一样：
int S = 20;
int W = 5;
int H = 5;
int[][] data = new int[W][H];
void setup(){
size(100,100);
noStroke();
}
void draw(){
background(0);
for (int y = 0 ; y < H; y++){
for (int x = 0 ; x < W; x++){
fill(data[x][y] * 255);
rect(x*S,y*S,S,S);
}
}
}
void mouseDragged(){
for (int y = 0 ; y < H; y++){
for (int x = 0 ; x < W; x++){
int xs = x * S;
int ys = y * S;
if ((mouseX > xs) && (mouseX < (xs+S)) && (mouseY >= ys && mouseY <= (ys+S))){
data[x][y] = 1;
}
}
}
}联合来文中的类似行为：
var S = 20;
var W = 5;
var H = 5;
var data = new Array(W);
function setup(){
createCanvas(100,100);
noStroke();
for (var i = 0 ; i < H; i++) data[i] = [0,0,0,0,0];
}
function draw(){
background(0);
for (var y = 0 ; y < H; y++){
for (var x = 0 ; x < W; x++){
fill(data[x][y] * 255);
rect(x*S,y*S,S,S);
}
}
}
function mouseDragged(){
for (var y = 0 ; y < H; y++){
for (var x = 0 ; x < W; x++){
var xs = x * S;
var ys = y * S;
if ((mouseX > xs) && (mouseX < (xs+S)) && (mouseY >= ys && mouseY <= (ys+S))){
data[x][y] = 1;
}
}
}
}<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.4.23/p5.min.js"></script>
我是否正确地用Python编写了方框边界条件？如果是这样的话，是否存在带有pyprocessing的bug？我怎么才能克服呢？
我用的是pyprocessing.version '0.1.3.22'
回答 1
Stack Overflow用户
回答已采纳
发布于 2016-03-22 17:38:10
试图变得懒惰是问题所在：
data = [[0] * W] * H这不仅仅是创建一个嵌套数组，它还复制了第一个数组( references，[0])的引用，所以当我修改一行中的一个值时，整个行都会被修改。
由于我对python非常熟悉，所以我以一种可能是非pythonic的方式初始化了数组：
data = []
for y in xrange(H):
data.append([])
for x in xrange(W):
data[y].append(0)因此，完整的工作代码是：
#!/usr/bin/env python
from pyprocessing import *
S = 20
W = 5
H = 5
# data = [[0] * W] * H #trouble
data = []
for y in xrange(H):
data.append([])
for x in xrange(W):
data[y].append(0)
def setup():
size(W*(S),H*(S))
def draw():
background(0)
for y in xrange(H):
for x in xrange(W):
fill(data[x][y] * 255)
rect(x*S,y*S,S,S)
def mouseDragged():
for y in xrange(H):
for x in xrange(W):
xs = x * S
ys = y * S
if (mouse.x >= xs) and (mouse.x <= (xs+S)) and (mouse.y >= ys and mouse.y <= (ys+S)):
if key.pressed:
data[x][y] = 0
else:
data[x][y] = 1
run()页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/36096135
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