基本上我有一个基本的形状，由键盘控制进行操作。我还有一些文字，我想在屏幕上显示“Hello world”。然而，每当我去运行它时，我只是得到一个空白屏幕。
这是我的代码，任何想法？
#include <iostream>
#include <stdio.h>
#include <Windows.h>
#include <string.h>
#include <GL/glut.h>
#include <math.h>
GLfloat g_xeye;
GLfloat g_yeye;
bool rollOn;
GLfloat g_light_position[] = {0.0, 10.0, 10.0, 0.0};
void roll(void)
{
if (rollOn){
Sleep(1);
g_xeye = g_xeye + 00000.1;
glutPostRedisplay();
g_yeye = g_yeye + 00000.1;
glutPostRedisplay();
}
}
void drawBitmapText(char *string, float x, float y, float z)
{
char *c;
glRasterPos3f(x, y, z);
for (c=string; *c != '\0'; c++)
{
glutBitmapCharacter(GLUT_BITMAP_TIMES_ROMAN_10, *c);
}
}
void drawStrokeText(char*string, int x, int y, int z)
{
char *c;
glPushMatrix();
glTranslatef(x, y+8, z);
for (c=string; *c != '\0'; c++)
{
glutStrokeCharacter(GLUT_STROKE_ROMAN, *c);
}
glPopMatrix();
}
void display(void)
{
GLfloat redDiffuseMaterial[] = {0.50, 0.0, 0.50, 0.0};
glClear (GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
gluLookAt(0,0, 6 , 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
glMaterialfv(GL_FRONT, GL_DIFFUSE, redDiffuseMaterial);
//glPushMatrix();
glRotatef(g_xeye, 1, 0, 0);
glRotatef(g_yeye, 0, 1, 0);
glutSolidCube(2.0);
//glPopMatrix();
//glColor3f(0.250, 0.0, 0.200);
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glColor3f(0,1,0);
drawBitmapText("Hello world",200,200,0);
glutSwapBuffers ();
}
void keyboard(unsigned char key, int x, int y)
{
if (key==27)
exit(0);
if (key == ',')
{
g_light_position[0] = g_light_position[0] - 1;
glLightfv(GL_LIGHT0, GL_POSITION, g_light_position);
}
if (key == '.')
{
g_light_position[0] = g_light_position[0] + 1;
glLightfv(GL_LIGHT0, GL_POSITION, g_light_position);
glutPostRedisplay();
}
if (key==32)
{
if(rollOn==false)
rollOn=true;
else
rollOn=false;
}
}
void special(int key, int x, int y)
{
if (key==27)
exit(0);
if (key == GLUT_KEY_UP)
{
g_xeye = g_xeye + 2;
glutPostRedisplay();
}
if (key == GLUT_KEY_DOWN)
{
g_xeye = g_xeye - 2;
glutPostRedisplay();
}
if (key == GLUT_KEY_RIGHT)
{
g_yeye = g_yeye + 2;
glutPostRedisplay();
}
if (key == GLUT_KEY_LEFT)
{
g_yeye = g_yeye - 2;
glutPostRedisplay();
}
}
void init(void)
{
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_POSITION, g_light_position);
rollOn = false;
g_xeye = 0;
g_yeye = 0;
}
void reshape (int width, int height)
{
/* Called when window is created, moved or resized */
GLfloat aspectRatio;
/* Set the viewport to be the whole window */
glViewport(0, 0, (GLsizei) width, (GLsizei) height);
/* Prepare to set up the Projection matrix */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//glColor3f(0.250, 0.0, 0.200);
gluOrtho2D(0, width, height, 0);
/* Set a prespective projection */
aspectRatio = (GLfloat)width / (GLfloat) height;
gluPerspective(60, aspectRatio, 1.0, 100.0);
/* Prepare to set up the Model view matrix */
glMatrixMode(GL_MODELVIEW);
glClearColor (0.0, 0.0, 0.0, 0.0);
glLoadIdentity();
}
/*void render(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glColor3f(0,1,0);
drawBitmapText("Hello world",200,200,0);
glutSwapBuffers();
}*/
int main(int argc, char** argv)
{
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(500,500);
glutInitWindowPosition(100, 100);
glutCreateWindow ("Project");
init();
glutKeyboardFunc(keyboard);
glutSpecialFunc(special);
glutReshapeFunc(reshape);
glutDisplayFunc(display);
glutIdleFunc(roll);
glutMainLoop();
return 0;
}
答案 0 :(得分：1)
试试这个：
#include <GL/glut.h>
GLfloat g_xeye;
GLfloat g_yeye;
bool rollOn;
GLfloat g_light_position[] = {0.0, 10.0, 10.0, 0.0};
void timer( int extra )
{
if (rollOn){
g_xeye = g_xeye + 00000.1;
g_yeye = g_yeye + 00000.1;
}
glutTimerFunc( 16, timer, 0 );
glutPostRedisplay();
}
void drawBitmapText(char *string, float x, float y, float z)
{
char *c;
glRasterPos3f(x, y, z);
for (c=string; *c != '\0'; c++)
{
glutBitmapCharacter(GLUT_BITMAP_TIMES_ROMAN_10, *c);
}
}
void display(void)
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glClear (GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT);
// draw cube in 3D
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
double w = glutGet( GLUT_WINDOW_WIDTH );
double h = glutGet( GLUT_WINDOW_HEIGHT );
gluPerspective(60, w / h, 1.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0, 0, 6, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
glPushMatrix();
glRotatef(g_xeye, 1, 0, 0);
glRotatef(g_yeye, 0, 1, 0);
GLfloat redDiffuseMaterial[] = {0.50, 0.0, 0.50, 0.0};
glMaterialfv(GL_FRONT, GL_DIFFUSE, redDiffuseMaterial);
glutSolidCube(2.0);
glPopMatrix();
// switch to 2D for text overlay
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho( 0, w, 0, h, -1, 1 );
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glDisable( GL_LIGHTING );
glColor3ub(255,255,255);
drawBitmapText("Hello world",200,200,0);
glEnable( GL_LIGHTING );
glutSwapBuffers ();
}
void keyboard(unsigned char key, int x, int y)
{
if (key==27)
exit(0);
if (key == ',')
{
g_light_position[0] = g_light_position[0] - 1;
}
if (key == '.')
{
g_light_position[0] = g_light_position[0] + 1;
glLightfv(GL_LIGHT0, GL_POSITION, g_light_position);
}
if (key==32)
{
rollOn = !rollOn;
}
}
void special(int key, int x, int y)
{
if (key==27)
exit(0);
if (key == GLUT_KEY_UP)
{
g_xeye = g_xeye + 2;
}
if (key == GLUT_KEY_DOWN)
{
g_xeye = g_xeye - 2;
}
if (key == GLUT_KEY_RIGHT)
{
g_yeye = g_yeye + 2;
}
if (key == GLUT_KEY_LEFT)
{
g_yeye = g_yeye - 2;
}
}
void init(void)
{
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glLightfv(GL_LIGHT0, GL_POSITION, g_light_position);
rollOn = false;
g_xeye = 0;
g_yeye = 0;
}
int main(int argc, char** argv)
{
glutInit( &argc, argv );
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(500,500);
glutInitWindowPosition(100, 100);
glutCreateWindow ("Project");
init();
glutKeyboardFunc(keyboard);
glutSpecialFunc(special);
glutDisplayFunc(display);
glutTimerFunc( 0, timer, 0 );
glutMainLoop();
return 0;
}
如果您愿意使用glWindowPos()中的OpenGL 1.4代替glRasterPos()，则可以避免2D切换。