【每日进步】June 2012

--------------------------------------------Mon June 4 2012-------------------------------------------------

Perl:

1. 安装Perl额外的库可以使用cpan，也可以自己下载下来安装。

2. 服务器安装的cpan，默认需要root权限（一些配置文件创建），报如下错误：

 

Your configuration suggests "/root/.cpan" as your
    CPAN.pm working directory. I could not create this directory due
    to this error: mkdir /root/.cpan: Permission denied at /usr/lib/perl5/5.6.1/CPAN.pm line 499

    Please make sure the directory exists and is writable.

在网上查到的解决方案如下：

$ mkdir ~/perl5lib
$ mkdir ~/.cpan
$ mkdir ~/.cpan/CPAN
$ echo "\$CPAN::Config = {}"> ~/.cpan/CPAN/MyConfig.pm
$ perl -MCPAN -e shell

之后跟着提示走就可以了。之后设定环境变量：export PERL5LIB=${PERL5LIB}:/your/lib/dir  export MANPATH=/your/man/dir

设定库目录时需要注意，库前缀，如Html::TreeBuilder 对应文件为~/path/Html/TreeBuilder.pm，设定路径时应设置为~/path，这一点类似java中的包的概念。

参考： http://www.dcc.fc.up.pt/~pbrandao/aulas/0203/AR/modules_inst_cpan.html   

--------------------------------------------Mon June 16 2012-------------------------------------------------

Windows：

1. 学习破解一个crackme程序，很简单的。

• 爆破：运行找到提示字符串，然后使用W32Dasm找到跳转位置：00401595 75 16 JNZ SHORT 004015AD，改成JZ运行就可以了。
• 找到注册码：使用O11yDbg找到00401595，向上寻找，使用的比较函数为lstrcmpA，设置断点，运行，找到注册码为 <BrD-SoB>。

2. 壳：pack unpack. 参考：http://baike.baidu.com/view/528311.htm  

--------------------------------------------Mon June 16 2012-------------------------------------------------

1. RenderMan坐标系统：Renderman渲染器初始化的摄像机空间坐标系(Camera Space)是最基本的坐标系。其它所有的坐标系都是相对于摄像机空间的。摄像机空间坐标系是一个左手坐标系，摄像机位于原点（0，0，0），它的＋x轴指向摄像机的右侧，＋y轴指向摄像机的上方，＋z轴指向摄像机的前方。
参考：http://kb.cnblogs.com/a/161878/ 

 --------------------------------------------Mon June 25 2012-------------------------------------------------

1. 使用LWP提交表单：

#!/usr/bin/perl

use strict;
use warnings;
use LWP;
use HTTP::Cookies;
use HTTP::Response;
use Encode

my $url = "地址";
my %form = (
         "username" => "namd",
        "password" => "1111",
        );

my  $browser = LWP::UserAgent->new;
my  $response = $browser->post($url,\%form);
if ($response->is_success) {
     print encode("GBK", $response->decoded_content);  # 这里假设返回文档为gbk编码
     print "\n";
}
else {
     die $response->status_line;
}

另外一种方式：

  use LWP::UserAgent;
  my $ua = LWP::UserAgent->new;

  my $req = HTTP::Request->new(POST => 'http://www.example.com/');
  $req->content_type('application/x-www-form-urlencoded');
  $req->content('key1=value1&key2=value2');

  my $res = $ua->request($req);
  print $res->as_string;

2.  概念

• Shader:Shaders are simple programs that describe the traits of either a vertex or a pixel. Vertex shaders describe the traits (position, texture coordinates, colors, etc.) of a vertex, while pixel shaders describe the traits (color, z-depth and alpha value) of a pixel.
• Three types of shaders: Pixel Shaders, Vertex Shaders, Geometry Shaders.
• The surface shader is used to specify the surface properties of subsequent geometric primitives. Calculate apparent surface opacity and color.
• Displacement shaders alter the smoothness of a surface, however, unlike bump mapping which mimics the appearance of bumpiness by reorientating surface normals, displacement shading genuinly effects the geometry of a surface. In the case of Pixars prman renderer, each object in a 3D scene is sub-divided into a fine mesh of micro-polygons after which, if a displacement shader has been assigned to an object, they are "pushed" or "pulled" in a direction that is parallel to the original surface normal of the micro-polygon. After displacing the micro-polygon the orientation of the local surface normal(N) is recalculated.

3. RenderMan Shader: 着色器通过接收一些可以由艺术家调节的变量比如Cs（表面颜色），Os（表面透明度）等，结合RenderMan渲染规范定义的内置变量N（着色点的法线），P（着色点位置)等，依据一定的算法计算出Ci（最终表面颜色），Oi（最终表面透明度）或任意所需信息，从而完成着色过程。

 --------------------------------------------Mon June 26 2012------------------------------------------------- 

1. cmd for 循环执行命令：for /l %%i in (1,1,1000000) do （这里放命令）

2. cmd中使用ping实现sleep，ping -n 60 -w 1000 0.0.0.1>nul （sleep一分钟）

3. 使用vbs实现bat脚本后台运行（没有窗口），bat中加入@echo off：

Set ws = CreateObject("Wscript.Shell")
ws.run "cmd /c run.bat",vbhide

--------------------------------------------Mon June 26 2012------------------------------------------------- 

1. PIXIE的运行需要设置PIXIEHOME，这样程序才能找到对应dll和shaders