Example 1-1 : A Simple OpenGL Program
#include 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#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
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选择类型,建议选择2nd or 3rd
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创建完毕的状态
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复制例子原始代码,覆盖main函数所在cpp文件全部
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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
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此处解决方案: 将aux.h修改为GLAUX.H#include
至此cpp包含的头文件如下
#include "StdAfx.h"
#include "windows.h"
#include
#include
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
#include #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
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此截图需要将sleep参数调整足够大!
【OpenGL Programming Guide- Red Book 例子程序库 -系列- 1-Introduction to OpenGL-Part1】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。
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