C++ 程序和作用域变量
c++ program and scope variables
我用 dev-c++ 编译了这个 c++ 程序，并为所有变量提供了 "was not declared in this scope"。
#include <cstdlib> // standard definitions
#include <iostream> // C++ I/O
#include <cstdio> // C I/O (for sprintf)
#include <cmath> // standard definitions
#include <GL/glut.h> // GLUT
#include <GL/glu.h> // GLU
#include <GL/gl.h> // OpenGL
using namespace std; // make std accessible
//-----------------------------------------------------------------------
// Global data
//-----------------------------------------------------------------------
GLint TIMER_DELAY = 10000; // timer delay (10 seconds)
GLfloat RED_RGB[] = {1.0, 0.0, 0.0}; // drawing colors
GLfloat BLUE_RGB[] = {0.0, 0.0, 1.0};
//-----------------------------------------------------------------------
// Global variables
//-----------------------------------------------------------------------
static bool isReversed = false; // draw reversed colors?
//-----------------------------------------------------------------------
// Callbacks
// The global variable "isReversed" describes the drawing state.
// When false, a blue rectangle is drawn on top of red diamond.
// When true the colors are reversed. The "isReversed" variable is
// complemented whenever the left mouse button is clicked or the
// timer goes off (every 10 seconds).
//-----------------------------------------------------------------------
void myReshape(int w, int h) {
cout << "MyReshape called width=" << w << " height=" << h << endl;
glViewport (0, 0, w, h); // update the viewport
glMatrixMode(GL_PROJECTION); // update projection
glLoadIdentity();
gluOrtho2D(0.0, 1.0, 0.0, 1.0); // map unit square to viewport
glMatrixMode(GL_MODELVIEW);
glutPostRedisplay(); // request redisplay
}
// draw diamond and rectangle
void drawObjects(GLfloat* diamColor, GLfloat* rectColor) {
glColor3fv(diamColor); // set diamond color
glBegin(GL_POLYGON); // draw the diamond
glVertex2f(0.90, 0.50);
glVertex2f(0.50, 0.90);
glVertex2f(0.10, 0.50);
glVertex2f(0.50, 0.10);
glEnd();
glColor3fv(rectColor); // set rectangle color
glRectf(0.25, 0.25, 0.75, 0.75); // draw the rectangle
}
void myDisplay(void) { // display callback
cout << "MyDisplay called" << endl;
glClearColor(0.5, 0.5, 0.5, 1.0); // background is gray
glClear(GL_COLOR_BUFFER_BIT); // clear the window
if (isReversed) // draw the objects
drawObjects(BLUE_RGB, RED_RGB);
else
drawObjects(RED_RGB, BLUE_RGB);
glutSwapBuffers(); // swap buffers
}
void myTimer(int id) { // timer callback
cout << "Timer just went off. Reversing colors." << endl;
isReversed = !isReversed; // reverse drawing colors
glutPostRedisplay(); // request redraw
glutTimerFunc(TIMER_DELAY, myTimer, 0); // reset timer for 10 seconds
}
void myMouse(int b, int s, int x, int y) { // mouse click callback
if (s == GLUT_DOWN) {
cout << "Mouse click detected at coordinates x="
<< x << " and y=" << y << endl;
if (b == GLUT_LEFT_BUTTON) {
isReversed = !isReversed;
cout << "Left mouse click. Reversing colors." << endl;
glutPostRedisplay();
}
}
}
// keyboard callback
void myKeyboard(unsigned char c, int x, int y) {
switch (c) { // c is the key that is hit
case 'q': // 'q' means quit
exit(0);
break;
default:
cout << "Hit q to quit. All other characters ignored" << endl;
break;
}
}
//-----------------------------------------------------------------------
// Main program
// This does all the set up for the program. It creates the game
// and then passes control to glut.
//-----------------------------------------------------------------------
int main(int argc, char** argv)
{
cout <<
"Colors swap every 10 seconds.\n"
"Click left mouse button to swap colors.\n" <<
"Try resizing and covering/uncovering the window.\n" <<
"Hit q to quit." << endl;
glutInit(&argc, argv); // OpenGL initializations
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);// double buffering and RGB
glutInitWindowSize(400, 400); // create a 400x400 window
glutInitWindowPosition(0, 0); // ...in the upper left
glutCreateWindow(argv[0]); // create the window
glutDisplayFunc(myDisplay); // setup callbacks
glutReshapeFunc(myReshape);
glutMouseFunc(myMouse);
glutKeyboardFunc(myKeyboard);
glutTimerFunc(TIMER_DELAY, myTimer, 0);
glutMainLoop(); // start it running
return 0; // ANSI C expects this
}
问题出在哪里？
[错误] 'glutPostRedisplay' 未在此范围内声明
[错误] 'glutSwapBuffers' 未在此范围内声明
[错误] 'glutPostRedisplay' 未在此范围内声明
[错误] 'glutTimerFunc' 未在此范围内声明
[错误] 'GLUT_DOWN' 未在此范围内声明
[错误] 'GLUT_LEFT_BUTTON' 未在此范围内声明
[错误] 'glutPostRedisplay' 未在此范围内声明
等等
您应该在该源文件中查找声明这些函数和变量的头文件以及include它们。
一个好的起点是您似乎包含 glut.h 的 GL 目录，假设它存在。
在不调用 main() 中的函数的情况下检查建筑物。然后一一尝试。我认为错误来自您的一个包含文件。
这些文件中是否定义了任何 classes。检查头文件是否正常。检查指定路径中是否存在头文件。
然后检查命名空间。如果您使用命名空间定义了 class，请不要忘记使用 using namespace namespace_name 或为变量指定完整的限定名称。
来自 GLUT 文档 here:
The header files for GLUT should be included in GLUT programs with the following include directive (which you have):
#include <GL/glut.h>
Because a very large window system software vendor (who will remain nameless) has an apparent inability to appreciate that OpenGL's API is independent of their window system API, portable ANSI C GLUT programs should not directly include <GL/gl.h> or <GL/glu.h>. Instead, ANSI C GLUT programs should rely on <GL/glut.h> to include the necessary OpenGL and GLU related header files.
如果您不在 windows，这可能会导致问题。
看起来确实没有正确包含此文件，因为即使是符号常量（例如 GLUT_DOWN）也没有被解析。
我用 dev-c++ 编译了这个 c++ 程序，并为所有变量提供了 "was not declared in this scope"。
#include <cstdlib> // standard definitions
#include <iostream> // C++ I/O
#include <cstdio> // C I/O (for sprintf)
#include <cmath> // standard definitions
#include <GL/glut.h> // GLUT
#include <GL/glu.h> // GLU
#include <GL/gl.h> // OpenGL
using namespace std; // make std accessible
//-----------------------------------------------------------------------
// Global data
//-----------------------------------------------------------------------
GLint TIMER_DELAY = 10000; // timer delay (10 seconds)
GLfloat RED_RGB[] = {1.0, 0.0, 0.0}; // drawing colors
GLfloat BLUE_RGB[] = {0.0, 0.0, 1.0};
//-----------------------------------------------------------------------
// Global variables
//-----------------------------------------------------------------------
static bool isReversed = false; // draw reversed colors?
//-----------------------------------------------------------------------
// Callbacks
// The global variable "isReversed" describes the drawing state.
// When false, a blue rectangle is drawn on top of red diamond.
// When true the colors are reversed. The "isReversed" variable is
// complemented whenever the left mouse button is clicked or the
// timer goes off (every 10 seconds).
//-----------------------------------------------------------------------
void myReshape(int w, int h) {
cout << "MyReshape called width=" << w << " height=" << h << endl;
glViewport (0, 0, w, h); // update the viewport
glMatrixMode(GL_PROJECTION); // update projection
glLoadIdentity();
gluOrtho2D(0.0, 1.0, 0.0, 1.0); // map unit square to viewport
glMatrixMode(GL_MODELVIEW);
glutPostRedisplay(); // request redisplay
}
// draw diamond and rectangle
void drawObjects(GLfloat* diamColor, GLfloat* rectColor) {
glColor3fv(diamColor); // set diamond color
glBegin(GL_POLYGON); // draw the diamond
glVertex2f(0.90, 0.50);
glVertex2f(0.50, 0.90);
glVertex2f(0.10, 0.50);
glVertex2f(0.50, 0.10);
glEnd();
glColor3fv(rectColor); // set rectangle color
glRectf(0.25, 0.25, 0.75, 0.75); // draw the rectangle
}
void myDisplay(void) { // display callback
cout << "MyDisplay called" << endl;
glClearColor(0.5, 0.5, 0.5, 1.0); // background is gray
glClear(GL_COLOR_BUFFER_BIT); // clear the window
if (isReversed) // draw the objects
drawObjects(BLUE_RGB, RED_RGB);
else
drawObjects(RED_RGB, BLUE_RGB);
glutSwapBuffers(); // swap buffers
}
void myTimer(int id) { // timer callback
cout << "Timer just went off. Reversing colors." << endl;
isReversed = !isReversed; // reverse drawing colors
glutPostRedisplay(); // request redraw
glutTimerFunc(TIMER_DELAY, myTimer, 0); // reset timer for 10 seconds
}
void myMouse(int b, int s, int x, int y) { // mouse click callback
if (s == GLUT_DOWN) {
cout << "Mouse click detected at coordinates x="
<< x << " and y=" << y << endl;
if (b == GLUT_LEFT_BUTTON) {
isReversed = !isReversed;
cout << "Left mouse click. Reversing colors." << endl;
glutPostRedisplay();
}
}
}
// keyboard callback
void myKeyboard(unsigned char c, int x, int y) {
switch (c) { // c is the key that is hit
case 'q': // 'q' means quit
exit(0);
break;
default:
cout << "Hit q to quit. All other characters ignored" << endl;
break;
}
}
//-----------------------------------------------------------------------
// Main program
// This does all the set up for the program. It creates the game
// and then passes control to glut.
//-----------------------------------------------------------------------
int main(int argc, char** argv)
{
cout <<
"Colors swap every 10 seconds.\n"
"Click left mouse button to swap colors.\n" <<
"Try resizing and covering/uncovering the window.\n" <<
"Hit q to quit." << endl;
glutInit(&argc, argv); // OpenGL initializations
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);// double buffering and RGB
glutInitWindowSize(400, 400); // create a 400x400 window
glutInitWindowPosition(0, 0); // ...in the upper left
glutCreateWindow(argv[0]); // create the window
glutDisplayFunc(myDisplay); // setup callbacks
glutReshapeFunc(myReshape);
glutMouseFunc(myMouse);
glutKeyboardFunc(myKeyboard);
glutTimerFunc(TIMER_DELAY, myTimer, 0);
glutMainLoop(); // start it running
return 0; // ANSI C expects this
}
问题出在哪里？
[错误] 'glutPostRedisplay' 未在此范围内声明
[错误] 'glutSwapBuffers' 未在此范围内声明
[错误] 'glutPostRedisplay' 未在此范围内声明
[错误] 'glutTimerFunc' 未在此范围内声明
[错误] 'GLUT_DOWN' 未在此范围内声明
[错误] 'GLUT_LEFT_BUTTON' 未在此范围内声明
[错误] 'glutPostRedisplay' 未在此范围内声明
等等
您应该在该源文件中查找声明这些函数和变量的头文件以及include它们。
一个好的起点是您似乎包含 glut.h 的 GL 目录，假设它存在。
在不调用 main() 中的函数的情况下检查建筑物。然后一一尝试。我认为错误来自您的一个包含文件。
这些文件中是否定义了任何 classes。检查头文件是否正常。检查指定路径中是否存在头文件。
然后检查命名空间。如果您使用命名空间定义了 class，请不要忘记使用 using namespace namespace_name 或为变量指定完整的限定名称。
来自 GLUT 文档 here:
The header files for GLUT should be included in GLUT programs with the following include directive
(which you have):
#include <GL/glut.h>Because a very large window system software vendor (who will remain nameless) has an apparent inability to appreciate that OpenGL's API is independent of their window system API, portable ANSI C GLUT programs should not directly include
<GL/gl.h>or<GL/glu.h>. Instead, ANSI C GLUT programs should rely on<GL/glut.h>to include the necessary OpenGL and GLU related header files.
如果您不在 windows，这可能会导致问题。
看起来确实没有正确包含此文件，因为即使是符号常量（例如 GLUT_DOWN）也没有被解析。