>>>>>>>>>>>>>>>>>>>>>>>>>>>>>Oct 3 2012<<<<<<<<<<<<<<<<<<<<<<<<<<<<
1. Bresenham's line algorithm（网上找的一个实现）
1 void PlotLine(int x1,int x2,int y1,int y2, char r, char g, char b) 2 { 3 int xinc1,yinc1; 4 int xinc2,yinc2; 5 int deltax = abs(x2 - x1); // The difference between the x's 6 int deltay = abs(y2 - y1); // The difference between the y's 7 int x = x1; // Start x off at the first pixel 8 int y = y1; 9 int den=0,num=0,numadd=0,numpixels=0,curpixel=0; // Start y off at the first pixel 10 11 12 if (x2 >= x1) // The x-values are increasing 13 { 14 xinc1 = 1; 15 xinc2 = 1; 16 } 17 else // The x-values are decreasing 18 { 19 xinc1 = -1; 20 xinc2 = -1; 21 } 22 23 if (y2 >= y1) // The y-values are increasing 24 { 25 yinc1 = 1; 26 yinc2 = 1; 27 } 28 else // The y-values are decreasing 29 { 30 yinc1 = -1; 31 yinc2 = -1; 32 } 33 34 if (deltax >= deltay) // There is at least one x-value for every y-value 35 { 36 xinc1 = 0; // Don't change the x when numerator >= denominator 37 yinc2 = 0; // Don't change the y for every iteration 38 den = deltax; 39 num = deltax >>1; 40 numadd = deltay; 41 numpixels = deltax; // There are more x-values than y-values 42 } 43 else // There is at least one y-value for every x-value 44 { 45 xinc2 = 0; // Don't change the x for every iteration 46 yinc1 = 0; // Don't change the y when numerator >= denominator 47 den = deltay; 48 num = deltay >>1; 49 numadd = deltax; 50 numpixels = deltay; // There are more y-values than x-values 51 } 52 53 54 for (curpixel = 0; curpixel <= numpixels; curpixel++) 55 { 56 DrawPixel(screen, x, y, r, g, b); 57 num += numadd; // Increase the numerator by the top of the fraction 58 if (num >= den) // Check if numerator >= denominator 59 { 60 num -= den; // Calculate the new numerator value 61 x += xinc1; // Change the x as appropriate 62 y += yinc1; // Change the y as appropriate 63 } 64 65 x += xinc2; // Change the x as appropriate 66 y += yinc2; // Change the y as appropriate 67 } 68 }
2. Reyes（Rendering everything you ever see）渲染架构，分为下面几个步骤:
- Bound，求包围盒
- Split，大的物体划分出小物体，方便将看不到的部分扔掉，同时一个细分网格不会包含太多细分面
- Dice，细分，存储到细分网格中
- Shade
- Sample
参考：http://www.steckles.com/reyes1.html
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>Oct 10 2012<<<<<<<<<<<<<<<<<<<<<<<<<<<<
1. error LNK2022: metadata operation failed (8013118D) : Inconsistent layout information in duplicated types
问题原因在于使用clr选项编译时，编译规则要比纯C++严格。当一个类型有个定义，但是内部结构不一致、大小不一致，就会出现该错误提示。
问题解决：出现该问题是使用了一个第三方库的一个类型MString，在有些问题中使用时没问题，有些就报错，后来发现是有几个头文件没加进来导致的
参考：http://social.msdn.microsoft.com/Forums/en/vclanguage/thread/079a2b60-951d-4e84-affc-8d8bfaf87cab
2. 调用第三方库函数，同一个类，有些函数可以调用，有些函数却报link错误，找不到符号，怀疑是类实现在多个lib中
dumpbin发现，该类确实在多个lib中，引入lib，问题解决
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>Oct 12 2012<<<<<<<<<<<<<<<<<<<<<<<<<<<<
1. Autoconf是linux上用来生成自动编译、安装脚本的工具
框架图如下：
下面介绍使用autoconf自动生成编译脚本的流程：
- 运行autoscan命令，生成configure.scan
- 将configure.scan 文件重命名为configure.in，并修改configure.in文件
主要修改AM_INIT_AUTOMAKE(package, version [, no-define])（第一个参数生成的程序名，第二个为版本）与AC_OUTPUT（对每一个要输出的Makefile都要添加）
示例：
# -*- Autoconf -*- # Process this file with autoconf to produce a configure script. AC_PREREQ(2.59) AC_INIT(test, 1.0, normalnotebook@126.com) AC_CONFIG_SRCDIR([src/ModuleA/apple/core/test.c]) AM_CONFIG_HEADER(config.h) AM_INIT_AUTOMAKE(test,1.0) # Checks for programs. AC_PROG_CC # Checks for libraries. # FIXME: Replace `main' with a function in `-lpthread': AC_CHECK_LIB([pthread], [pthread_rwlock_init]) AC_PROG_RANLIB # Checks for header files. # Checks for typedefs, structures, and compiler characteristics. # Checks for library functions. AC_OUTPUT([Makefile src/lib/Makefile src/ModuleA/apple/core/Makefile src/ModuleA/apple/shell/Makefile ])
- 在工程目录下新建Makefile.am文件，并在需要编译的子目录也新建makefile.am文件（以下是一个示例文件）
AM_CFLAGS = $(X_CFLAGS) ## Add warnings for gcc-3.4 AM_CFLAGS += -Wall -Wunused -Wimplicit -Wreturn-type AM_CFLAGS += -Wdeclaration-after-statement -Wno-unknown-pragmas AM_CFLAGS += -Wmissing-prototypes -Wmissing-declarations -Wparentheses AM_CFLAGS += -Wswitch -Wtrigraphs -Wpointer-arith -Wcast-qual AM_CFLAGS += -Wcast-align -Wwrite-strings -Wold-style-definition LDADD = $(X_LIBS) -lX11 -lXmu $(X_EXTRA_LIBS) EXTRA_DIST = pdfopen-AR-7-and-8.c bin_PROGRAMS = pdfopen pdfclose pdfopen_SOURCES = pdfopen.c sendx.c utils.c sendx.h xpdfopen.h utils.h pdfclose_SOURCES = pdfclose.c sendx.c utils.c sendx.h xpdfopen.h utils.h
- 在工程目录下新建NEWS、 README、 ChangeLog 、AUTHORS文件
- 将/usr/share/automake-1.X/目录下的depcomp和complie文件拷贝到本目录下
- 运行aclocal命令
- 运行autoconf命令
- 运行automake -a命令，生成Makefile.in
- 运行autoheader命令，生成config.h.in
- 运行./confiugre脚本
2. 前缀树：trie或者prefix tree(前缀树),是一种有序树数据结构,它通常被存储在一个以字符串为关键字的联合数组中。于二叉搜索树不同，在树里没有结点存储与结点相关联的关键字。它是用它在树中的位置展示与它相关的关键字。
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>Oct 19 2012<<<<<<<<<<<<<<<<<<<<<<<<<<<<
1. 编译boost时发现，boost使用jam来编译整个工程，而不是使用make。jam简单，而且跨平台。
参考：http://www.freetype.org/jam/index.html
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>Oct 24 2012<<<<<<<<<<<<<<<<<<<<<<<<<<<<
1. Consider the "right-end" of curve f(b) and the "left-end" of curve g(m). If f(b) and g(m) are equal as shown in the above figure, we shall say curves f() and g() are C0continuous at f(b)=g(m). If for all i <= k, the i-th derivatives at f(b) and g(m) are equal, we shall say that the curves are Ck continuous at point f(b)=g(m).