OpenGL Programming Guide- Red Book 例子程序库 -系列- 2-Introduction to OpenGL-Part2

Example 1-3 : A Double-Buffered Program: double.c

原始程序

#include <GL/gl.h>#include <GL/glu.h>#include <GL/glx.h>#include "aux.h"static GLfloat spin = 0.0;void display(void){    glClear(GL_COLOR_BUFFER_BIT);    glPushMatrix();    glRotatef(spin, 0.0, 0.0, 1.0);    glRectf(-25.0, -25.0, 25.0, 25.0);    glPopMatrix();    glFlush();    glXSwapBuffers(auxXDisplay(), auxXWindow());}void spinDisplay(void){    spin = spin + 2.0;    if (spin > 360.0)        spin = spin - 360.0;    display();}void startIdleFunc(AUX_EVENTREC *event){    auxIdleFunc(spinDisplay);}void stopIdleFunc(AUX_EVENTREC *event){    auxIdleFunc(0);}void myinit(void){    glClearColor(0.0, 0.0, 0.0, 1.0);    glColor3f(1.0, 1.0, 1.0);    glShadeModel(GL_FLAT);}void myReshape(GLsizei w, GLsizei h){    glViewport(0, 0, w, h);    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    if (w <= h)         glOrtho (-50.0, 50.0, -50.0*(GLfloat)h/(GLfloat)w,             50.0*(GLfloat)h/(GLfloat)w, -1.0, 1.0);    else         glOrtho (-50.0*(GLfloat)w/(GLfloat)h,             50.0*(GLfloat)w/(GLfloat)h, -50.0, 50.0, -1.0, 1.0);    glMatrixMode(GL_MODELVIEW);    glLoadIdentity ();}int main(int argc, char** argv){    auxInitDisplayMode(AUX_DOUBLE | AUX_RGBA);    auxInitPosition(0, 0, 500, 500);    auxInitWindow(argv[0]);    myinit();    auxReshapeFunc(myReshape);    auxIdleFunc(spinDisplay);    auxMouseFunc(AUX_LEFTBUTTON, AUX_MOUSEDOWN, startIdleFunc);    auxMouseFunc(AUX_MIDDLEBUTTON, AUX_MOUSEDOWN, stopIdleFunc);    auxMainLoop(display);}

和前例一样添加了必要的头文件和lib之后

编译错误__stdcall

--------------------Configuration: Example_1_3 - Win32 Debug--------------------Compiling...Example_1_3.cppE:\OpenGLRB\Example_1_3\Example_1_3.cpp(31) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of dataE:\OpenGLRB\Example_1_3\Example_1_3.cpp(33) : warning C4244: '=' : conversion from 'double' to 'float', possible loss of dataE:\OpenGLRB\Example_1_3\Example_1_3.cpp(39) : error C2664: 'auxIdleFunc' : cannot convert parameter 1 from 'void (void)' to 'void (__stdcall *)(void)'        None of the functions with this name in scope match the target typeE:\OpenGLRB\Example_1_3\Example_1_3.cpp(76) : error C2664: 'auxReshapeFunc' : cannot convert parameter 1 from 'void (int,int)' to 'void (__stdcall *)(int,int)'        None of the functions with this name in scope match the target typeE:\OpenGLRB\Example_1_3\Example_1_3.cpp(77) : error C2664: 'auxIdleFunc' : cannot convert parameter 1 from 'void (void)' to 'void (__stdcall *)(void)'        None of the functions with this name in scope match the target typeE:\OpenGLRB\Example_1_3\Example_1_3.cpp(78) : error C2664: 'auxMouseFunc' : cannot convert parameter 3 from 'void (struct _AUX_EVENTREC *)' to 'void (__stdcall *)(struct _AUX_EVENTREC *)'        None of the functions with this name in scope match the target typeE:\OpenGLRB\Example_1_3\Example_1_3.cpp(79) : error C2664: 'auxMouseFunc' : cannot convert parameter 3 from 'void (struct _AUX_EVENTREC *)' to 'void (__stdcall *)(struct _AUX_EVENTREC *)'        None of the functions with this name in scope match the target typeE:\OpenGLRB\Example_1_3\Example_1_3.cpp(80) : error C2664: 'auxMainLoop' : cannot convert parameter 1 from 'void (void)' to 'void (__stdcall *)(void)'        None of the functions with this name in scope match the target typeE:\OpenGLRB\Example_1_3\Example_1_3.cpp(81) : warning C4508: 'main' : function should return a value; 'void' return type assumedError executing cl.exe.Creating browse info file...Example_1_3.exe - 6 error(s), 3 warning(s)

其中的

error C2664: 'auxMainLoop' : cannot convert parameter 1 from 'void (void)' to 'void (__stdcall *)(void)'

该错误处理方案为在各函数前添加__stdcall符号，如下

void __stdcall stopIdleFunc(AUX_EVENTREC *event){    auxIdleFunc(0);}void __stdcall myinit(void){    glClearColor(0.0, 0.0, 0.0, 1.0);    glColor3f(1.0, 1.0, 1.0);    glShadeModel(GL_FLAT);}

原始代码是在XWindows下面的编写的，转WindowVC，glx.h是无效的，glXSwapBuffers(auxXDisplay(), auxXWindow());函数调用也无效，改为auxSwapBuffers();

调整后cpp文件

// Example_1_3.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")static GLfloat spin = 0.0;void __stdcall display(void){    glClear(GL_COLOR_BUFFER_BIT);    glPushMatrix();    glRotatef(spin, 0.0, 0.0, 1.0);    glRectf(-25.0, -25.0, 25.0, 25.0);    glPopMatrix();    glFlush();    //glXSwapBuffers(auxXDisplay(), auxXWindow());    auxSwapBuffers();}void  __stdcall spinDisplay(void){    spin = spin + 2.0;    if (spin > 360.0)        spin = spin - 360.0;    display();} void __stdcall startIdleFunc(AUX_EVENTREC *event){    auxIdleFunc(spinDisplay);}void __stdcall stopIdleFunc(AUX_EVENTREC *event){    auxIdleFunc(0);}void __stdcall myinit(void){    glClearColor(0.0, 0.0, 0.0, 1.0);    glColor3f(1.0, 1.0, 1.0);    glShadeModel(GL_FLAT);}void __stdcall myReshape(GLsizei w, GLsizei h){    glViewport(0, 0, w, h);    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    if (w <= h)         glOrtho (-50.0, 50.0, -50.0*(GLfloat)h/(GLfloat)w, 50.0*(GLfloat)h/(GLfloat)w, -1.0, 1.0);    else         glOrtho (-50.0*(GLfloat)w/(GLfloat)h, 50.0*(GLfloat)w/(GLfloat)h, -50.0, 50.0, -1.0, 1.0);    glMatrixMode(GL_MODELVIEW);    glLoadIdentity ();}int main(int argc, char** argv){    auxInitDisplayMode(AUX_DOUBLE | AUX_RGBA);    auxInitPosition(0, 0, 500, 500);    auxInitWindow(argv[0]);    myinit();    auxReshapeFunc(myReshape);    auxIdleFunc(spinDisplay);    auxMouseFunc(AUX_LEFTBUTTON, AUX_MOUSEDOWN, startIdleFunc);    auxMouseFunc(AUX_MIDDLEBUTTON, AUX_MOUSEDOWN, stopIdleFunc);    auxMainLoop(display);return 0;}

后记：此程序将Example1-1中的代码分散在多个函数中，但是流程顺序保持不变，通过改变参数实现动画效果，鼠标中键单击停止，左键单击启动。

所有aux开头的函数都不重要，所有gl开头的函数都是必须理解掌握的。