OpenGL Programming Guide- Red Book 例子程序库 -系列- 1-Introduction to OpenGL-Part1

Example 1-1 : A Simple OpenGL Program

#include <whateverYouNeed.h>

main() {

OpenAWindowPlease();

glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glBegin(GL_POLYGON);
glVertex2f(-0.5, -0.5);
glVertex2f(-0.5, 0.5);
glVertex2f(0.5, 0.5);
glVertex2f(0.5, -0.5);
glEnd();
glFlush();

KeepTheWindowOnTheScreenForAWhile();
}

此程序无法编译通过，但把GL编程的核心内容和架构体现出来了

glClearColor(0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glBegin(GL_POLYGON);
glVertex2f(-0.5, -0.5);
glVertex2f(-0.5, 0.5);
glVertex2f(0.5, 0.5);
glVertex2f(0.5, -0.5);
glEnd();
glFlush();

以上代码结构在后续例子中将反复出现

Example 1-2 : A Simple OpenGL Program Using the Auxiliary Library: simple.c

原始程序

#include <GL/gl.h>
#include "aux.h"

int main(int argc, char** argv)
{
auxInitDisplayMode (AUX_SINGLE | AUX_RGBA);
auxInitPosition (0, 0, 500, 500);
auxInitWindow (argv[0]);

glClearColor (0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glBegin(GL_POLYGON);
glVertex2f(-0.5, -0.5);
glVertex2f(-0.5, 0.5);
glVertex2f(0.5, 0.5);
glVertex2f(0.5, -0.5);
glEnd();
glFlush();

sleep(10);
}

VC项目创建步骤

新建Win32 Console 项目

选择类型，建议选择2nd or 3rd

创建完毕的状态

复制例子原始代码，覆盖main函数所在cpp文件全部

第一轮编译错误

--------------------Configuration: Example_1_2 - Win32 Debug--------------------
Compiling...
StdAfx.cpp
Compiling...
Example_1_2.cpp
e:\openglrb\example_1_2\example_1_2.cpp(29) : fatal error C1010: unexpected end of file while looking for precompiled header directive
Error executing cl.exe.

Example_1_2.exe - 1 error(s), 0 warning(s)

解决方法，在example_1_2.cpp的头部第一行包含stdafx.h

第二轮编译错误

--------------------Configuration: Example_1_2 - Win32 Debug--------------------
Compiling...
Example_1_2.cpp
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2144: syntax error : missing ';' before type 'void'
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2501: 'WINGDIAPI' : missing storage-class or type specifiers
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : fatal error C1004: unexpected end of file found
Error executing cl.exe.

Example_1_2.exe - 3 error(s), 0 warning(s)

百度搜索WINGDIAPI 可见该错误，原因是VC INCLUDE的gl.h文件是被Windows调整过的，和Qt开发库里面的gl.h内容上有区别

WINGDIAPI void APIENTRY glAccum (GLenum op, GLfloat value);
WINGDIAPI void APIENTRY glAlphaFunc (GLenum func, GLclampf ref);
WINGDIAPI GLboolean APIENTRY glAreTexturesResident (GLsizei n, const GLuint *textures, GLboolean *residences);
WINGDIAPI void APIENTRY glArrayElement (GLint i);
WINGDIAPI void APIENTRY glBegin (GLenum mode);
WINGDIAPI void APIENTRY glBindTexture (GLenum target, GLuint texture);
WINGDIAPI void APIENTRY glBitmap (GLsizei width, GLsizei height, GLfloat xorig, GLfloat yorig, GLfloat xmove, GLfloat ymove, const GLubyte *bitmap);
WINGDIAPI void APIENTRY glBlendFunc (GLenum sfactor, GLenum dfactor);
WINGDIAPI void APIENTRY glCallList (GLuint list);

此处解决方案: 在stdafx.h中增加包含 windows.h，如果在example_1_2.cpp中包含，需要在包含gl.h之前

第三轮编译错误

--------------------Configuration: Example_1_2 - Win32 Debug--------------------
Compiling...
Example_1_2.cpp
E:\OpenGLRB\Example_1_2\Example_1_2.cpp(6) : fatal error C1083: Cannot open include file: 'aux.h': No such file or directory
Error executing cl.exe.

Example_1_2.exe - 1 error(s), 0 warning(s)

没有aux.h,此文件已被更名为glaux.h,和gl.h在同一文件夹



此处解决方案:
将aux.h修改为GLAUX.H #include <GL/glaux.h>

至此cpp包含的头文件如下

#include "StdAfx.h"
#include "windows.h"
#include <GL/gl.h>
#include <GL/glaux.h>

第四轮编译错误

--------------------Configuration: Example_1_2 - Win32 Debug--------------------
Compiling...
Example_1_2.cpp
E:\OpenGLRB\Example_1_2\Example_1_2.cpp(28) : error C2065: 'sleep' : undeclared identifier
E:\OpenGLRB\Example_1_2\Example_1_2.cpp(29) : warning C4508: 'main' : function should return a value; 'void' return type assumed
Error executing cl.exe.

Example_1_2.exe - 1 error(s), 1 warning(s)

解决方案， sleep函数首字母大写，main 函数结尾增加return 语句，或者将函数返回类型改为void, sleep(10)中的10是窗口生存时间，毫秒，需要改大一些

第五轮编译错误

--------------------Configuration: Example_1_2 - Win32 Debug--------------------
Compiling...
Example_1_2.cpp
Linking...
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glFlush@0
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glEnd@0
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glVertex2f@8
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glBegin@4
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glOrtho@48
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glLoadIdentity@0
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glMatrixMode@4
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glColor3f@12
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glClear@4
Example_1_2.obj : error LNK2001: unresolved external symbol __imp__glClearColor@16
Example_1_2.obj : error LNK2001: unresolved external symbol _auxInitWindowA@4
Example_1_2.obj : error LNK2001: unresolved external symbol _auxInitPosition@16
Example_1_2.obj : error LNK2001: unresolved external symbol _auxInitDisplayMode@4
Debug/Example_1_2.exe : fatal error LNK1120: 13 unresolved externals
Error executing link.exe.

Example_1_2.exe - 14 error(s), 0 warning(s)

此处错误为链接错误，源文件的语法、拼写错误已解决

解决方案为引入OpenGL相关的lib文件

#pragma comment(lib,"opengl32.lib")
#pragma comment(lib,"glaux.lib")

至此编译链接全部通过，当前main函数cpp文件内容如下

// Example_1_2.cpp : Defines the entry point for the console application.
//
#include "StdAfx.h"
#include "windows.h"
#include <GL/gl.h>
#include <GL/glaux.h>

#pragma comment(lib,"opengl32.lib")
#pragma comment(lib,"glaux.lib")

int main(int argc, char** argv)
{
auxInitDisplayMode (AUX_SINGLE | AUX_RGBA);
auxInitPosition (0, 0, 500, 500);
auxInitWindow (argv[0]);

glClearColor (0.0, 0.0, 0.0, 0.0);
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
glBegin(GL_POLYGON);
glVertex2f(-0.5, -0.5);
glVertex2f(-0.5, 0.5);
glVertex2f(0.5, 0.5);
glVertex2f(0.5, -0.5);
glEnd();
glFlush();

Sleep(1000);

return 0;
}

运行截图

此截图需要将sleep参数调整足够大！

后记，本文针对第一章第二个例子给出了完整的编译排错流程，后续各例子将仅提供原始代码。调整后的代码、运行结果及必要的说明。