【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