更改每个像素的图像并保存到db [英] Change image per pixel and save to db

问题描述

我正在做一个网络游戏，我正在寻找一个方法来处理每个像素的图像，并将其存储在一个mysql数据库。确切地说，我需要能够执行以下操作：

I'm making a little web-game and I'm looking for a method to manipulate an image per pixel and store it in a mysql db. To be precise, I need to be able to do the following:

• 从屏幕上的mysql db加载图片（250 x 250px）例如，每个像素的alpha是0）;


• 随机选择几个像素，将alpha设置为1;


• 将新图片保存在mysql db中的旧图片


• 加载包含多个像素的新图片;


• 随机选择几个像素en将alpha设置为1;
  等..

• load image (250 x 250px) from mysql db on screen (image is not visible. For example, the alpha of each pixel is 0);
• Randomly pick a few pixels en set the alpha to 1;
• Save the new image over the old image in the mysql db
• load new image with a number of pixels visible;
• randomly pick a few pixels en set the alpha to 1; etc..

我已经设法让这个东西工作，但是效率非常低。我有我的mysql数据库的成千上万的记录，在每个记录是一个像素存储与正确的位置，颜色和可见性。当图像渲染到屏幕上时，需要读取每个记录。

I've managed to get this thing worked, but in an very inefficient way. I have thousands of records in my mysql db and in each record is a pixel stored with the right position, color and visibility. When the image is rendered to the screen, each record needs to be read out.

我看过html5画布，但还没有找到正确的方法。其实，这时候我不知道最好的方法是什么。希望有人可以帮助这里。

I've looked at html5 canvas but haven't been able yet to figure out the right way. Actually, at this moment I don't know what the best way is. Hope someone can help here.

推荐答案

听起来像我想要的是一个线性同余随机数生成器。它们实际上是一个LOT LOT LOT更复杂的描述（甚至写的名称！）比他们编程和使用。

Sounds to me like what you want is a linear congruential random number generator. They are actually a LOT LOT LOT more complicated to describe (or even write the name of!) than they are to program and use. They're really easy to use.

http://en.wikipedia.org/wiki/Linear_congruential_generator

使用这些，您只能传递当前的 seed value（这是您首先设置的像素，或您先前设置的像素）到表达式中：

Using these, you can pass just the current seed value (which is the pixel you picked to set first, or which pixel you previously set, into the expression:

seed = ((seed * multiplier) + increment) % modulus.

选择值如下：
seed =您的初始值必须大于0并小于模数。

Pick the values as follows: seed = your initial value must be bigger than 0 and smaller than modulus.

modulus =图片中的总像素数（即 width * height ）， 2 ^ 31或更少的工作在PHP。它可以多一点，虽然你的代码将不太有效：下一个2的幂大于像素数量可能是一个不错的选择。

modulus = the total number of pixels in your image (ie, width * height), which must be 2^31 or less to work in PHP. It can be a bit more, though your code will be less efficient: the next power of 2 larger than the number of pixels might be a good choice.

increment = Easiest：1或者，素数最多为23,622,320,123。或者如果不是这样，那么至少与模量相关，并且小于（2 ^ 53-（模数*乘数））。

increment = Easiest: "1". Or, a prime number at most 23,622,320,123. Or if not that, then at the very least relatively prime with the modulus, and smaller than (2^53-(modulus*multiplier)).

乘法器：

• 一个超过模数的所有素因子可分割的数字。 >
  
• 如果模数是4的倍数，则为1的倍数。


• 小于2 ^ 22。

<如果你选择一个2的幂的模数，那么这个乘数可以是（小的素数* 4）+ 1。所以，5或9，或者什么。

仔细选择值将意味着当你重复种子生成代码 modulus 次时，你永远不会得到重复的数字 -

This careful selection of values will mean that when you repeat that seed generation code modulus times, you will never get a repeated number - you will semi-randomly "select" every single pixel only once.

如果您的模数大于 width * height ，您有时会选择一个不在图片中的像素：如果您的图片为10x10或100像素，而您选择了模数为128（下一个最大幂为2），那么你有机会选择100和127之间的数字。在这种情况下，你可以再次循环，直到获得一个有效的像素，或者只是更改较少的像素。

If your modulus is larger than width * height, you will sometimes select a pixel that's not "in" your image: if your image is 10x10, or 100 pixels, and you picked a modulus of 128 (next largest power of 2), then you'd have a chance of it picking numbers between 100 and 127. In this case you can just loop it again until you get a valid pixel, or just change fewer pixels.

但如果它选择一个像素从0到99，那将是使用的像素。因此，对于10x10图像，37的种子可能意味着第四行，第八像素。

But if it picked a pixel from 0 to 99, that'd be the pixel to use. So for a 10x10 image, a seed of 37 might mean fourth row, eighth pixel.

具体：

$pixelX = $seed / $width;
$pixelY = $seed % $width;

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