使用两个纹理：输出窗口不保留在屏幕上

Posted 2023-05-07

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【中文标题】使用两个纹理：输出窗口不保留在屏幕上【英文标题】：Using Two Textures: Output Window Doesn't Retain On Screen 【发布时间】：2013-05-12 04:49:55 【问题描述】：

此代码最初使用一种纹理。我复制了一些函数来使用两个纹理。似乎没有任何错误，但是当我运行时，我只看到黑色的命令窗口一会儿然后它就关闭了。我应该添加任何其他行吗？

#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "support.h"

using namespace std;

/* GLUT callback Handlers */
MYPOINT*ptsW,*ptsR;
MYFACE *faceW,*faceR;

GLuint *images;
GLubyte *image;
GLuint texture;
void loadImage(int n, int m, char *fName);
GLuint LoadTexture(int width, int height);

int n=200,m=200;

void constructBox();
void constructTri();
void init();
void showPictureW();
void showPictureR();

float rX=0, rY=0, rZ=0;
float tX=0, tY=0, tZ=-3.5;
float nr = -5.0;
float fr = -4.0;
float tpx = 1.0, tpy = 1.0;
float btx = -1.0, bty = -1.0;
float dZ =-2.0;

void init()
constructBox();
loadImage(n,m,"wall.ppm");
constructTri();
loadImage(n,m,"roof.ppm");


void showPictureW()
/*  clear all pixels  */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
texture = LoadTexture(n,m);
glEnable( GL_TEXTURE_2D );
glBindTexture( GL_TEXTURE_2D, texture );

glColor3d(1,1,1);

//face 1
glBegin( GL_POLYGON );
glTexCoord2d(1.0,1.0); glVertex3d(-1.0,1.0,-2.0);
glTexCoord2d(1.0,0.0); glVertex3d(-1,-1.0,-2.0);  //1 -1
glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,-2.0); //-1 -1
glEnd();

//face 2
glBegin( GL_POLYGON );
glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,-2.0);
glTexCoord2d(0.0,1.0); glVertex3d(1.0,1.0,-2.0);
glTexCoord2d(1.0,1.0); glVertex3d(-1.0,1.0,-2.0);  //1 -1   
glEnd();


void showPictureR()
/*  clear all pixels  */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
texture = LoadTexture(n,m);
glEnable( GL_TEXTURE_2D );
glBindTexture( GL_TEXTURE_2D, texture );

glColor3d(1,1,1);

//face 1
glBegin( GL_POLYGON );
glTexCoord2d(1.0,1.0); glVertex3d(-1.0,1.0,-2.0);
glTexCoord2d(1.0,0.0); glVertex3d(-1,-1.0,-2.0);  //1 -1
glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,-2.0); //-1 -1
glEnd();

//face 2
glBegin( GL_POLYGON );
glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,0.0);
glTexCoord2d(0.0,1.0); glVertex3d(1.0,3.0,-2.0);
glTexCoord2d(1.0,1.0); glVertex3d(-1.0,3.0,-2.0);  //1 -1   
glEnd();


static void 
resize(int width, int height)

const float ar = (float) width / (float) height;

glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-ar, ar, -1.0, 1.0, 1.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity() ;
init();


static void 
display(void)

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3d(1,0,0);

glPushMatrix();
glTranslated(0,0,0);
glRotated(rX,0,0,1);
glRotated(rY,0,1,0);
glRotated(rZ,1,0,0);
showPictureW();
glPopMatrix();

glPushMatrix();
glTranslated(0,0,0);
glRotated(rX,0,0,1);
glRotated(rY,1,1,0);
glRotated(rZ,1,0,0);
showPictureR();
glPopMatrix();

glutSwapBuffers();


void constructBox()

int nPtsW = 8;
int nFaceW = 12;
ptsW = new MYPOINT[nPtsW];
faceW = new MYFACE[nFaceW];
getPoints(ptsW,"myVertWall.txt");
getFace(faceW,"myFaceWall.txt");


void constructTri()

int nPtsR = 6;
int nFaceR = 8;
ptsR = new MYPOINT[nPtsR];
faceR = new MYFACE[nFaceR];
getPoints(ptsR,"myVertRoof.txt");
getFace(faceR,"myFaceRoof.txt");


static void 
key(unsigned char key, int x, int y)

    switch (key) 
    
    case 27 : 
    case 'q':
        exit(0);
        break;

    case '+':    
        break;

    case 'x':
          rX= rX + 0.5;
        break;

    case  'X':
          rX= rX - 0.5;
        break;  

    case 'y':
          rY= rY + 0.5;
        break;   

    case 'Y':
          rY= rY - 0.5;    
        break;

    case 'z':
          rZ= rZ + 0.5;    
        break;

    case 'Z':
          rZ= rZ - 0.5;
        break;         

    case 'd':
        dZ = dZ+100.0;// horizontal movement to the left
        printf("Nilai dZ=%.2f\n",dZ);
        break;

    case 'D':
        dZ = dZ-100.0;// horizontal movement to the right
        printf("Nilai dZ=%.2f\n",dZ);
        break;

glutPostRedisplay();


static void 
idle(void)

glutPostRedisplay();


const GLfloat light_ambient[]  =  0.0f, 0.0f, 0.0f, 1.0f ;
const GLfloat light_diffuse[]  =  1.0f, 1.0f, 1.0f, 1.0f ;
const GLfloat light_specular[] =  1.0f, 1.0f, 1.0f, 1.0f ;
const GLfloat light_position[] =  2.0f, 5.0f, 5.0f, 0.0f ;

const GLfloat mat_ambient[]    =  0.7f, 0.7f, 0.7f, 1.0f ;
const GLfloat mat_diffuse[]    =  0.8f, 0.8f, 0.8f, 1.0f ;
const GLfloat mat_specular[]   =  1.0f, 1.0f, 1.0f, 1.0f ;
const GLfloat high_shininess[] =  100.0f ;

/* Program entry point */

int main(int argc, char *argv[])

glutInit(&argc, argv);
glutInitWindowSize(640,480);
glutInitWindowPosition(10,10);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);

glutCreateWindow("FreeGLUT Shapes");
glutReshapeFunc(resize);
glutDisplayFunc(display);
glutKeyboardFunc(key);
glutIdleFunc(idle);

glClearColor(1,1,1,1);
glEnable(GL_CULL_FACE);
glCullFace(GL_BACK);

glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LESS);

glEnable(GL_LIGHT0);
glEnable(GL_NORMALIZE);
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_LIGHTING);

glLightfv(GL_LIGHT0, GL_AMBIENT,  light_ambient);
glLightfv(GL_LIGHT0, GL_DIFFUSE,  light_diffuse);
glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
glLightfv(GL_LIGHT0, GL_POSITION, light_position);

glMaterialfv(GL_FRONT, GL_AMBIENT,   mat_ambient);
glMaterialfv(GL_FRONT, GL_DIFFUSE,   mat_diffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR,  mat_specular);
glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);

glutMainLoop();

return EXIT_SUCCESS;


GLuint LoadTexture(int width, int height)


image = new BYTE[width*height*3*sizeof(BYTE)];
int nm = width*height;
for(int i=0;i<nm*3;i++)//copy each value 3 times

image[i] = (GLubyte)images[i];
image[i] = (GLubyte)images[i];
image[i] = (GLubyte)images[i];
  

bool wrap = true;
glGenTextures( 1, &texture );
// select our current texture
glBindTexture( GL_TEXTURE_2D, texture );
// select modulate to mix texture with color for shading
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
// when texture area is small, bilinear filter the closest mipmap
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST );
// when texture area is large, bilinear filter the first mipmap
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
// if wrap is true, the texture wraps over at the edges (repeat)
//       ... false, the texture ends at the edges (clamp)
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap ? GL_REPEAT : GL_CLAMP );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,wrap ? GL_REPEAT : GL_CLAMP );
// build our texture mipmaps
gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,
                   GL_RGB, GL_UNSIGNED_BYTE, image );

// free buffer
//free( data );

return texture;


void loadImage(int n, int m, char *fName)

  FILE *fd;
  int k, nm;
  int i;
  char bc[71];
  float s;
  unsigned int red, green, blue;
  char c;

  fd = fopen(fName,"r");
  fscanf(fd,"%[^\n]",bc); // reads data from stream
  printf("Nilai %s \n\n",bc);
  if(bc[0]!='P'|| bc[1]!='3')
  
     printf("%s Not a PPM file\n",bc);
     exit(0);
  
  printf("%s is a PPM file\n",bc);

  fscanf(fd,"%s",bc);
  printf("line 1 %s \n",bc);

  fscanf(fd,"%s",bc);
  printf("line 2 %s \n",bc);

  fscanf(fd,"%s",bc);
  printf("line 3 %s \n",bc);

  fscanf(fd,"%s",bc);
  printf("line 4 %s \n",bc);

  fscanf(fd,"%c",&c);
  ungetc(c,fd);
  fscanf(fd,"%d %d %d", &n,&m,&k);
  //  printf("%d rows %d columns max value = %d\n",n,m,k);

  nm = n*m;
  images = new GLuint[3*sizeof(GLuint)*nm];

  //s = 255./k;
  for (i=0;i<nm;i++)
  
     fscanf(fd,"%u %u %u", &red, &green, &blue);
     images[3*nm-3*i-3] = red;
     images[3*nm-3*i-2] = green;
     images[3*nm-3*i-1] = blue;

  
  int totSize = 3*nm;
  int tot=0;
  for(i=0;i<nm;i++)
  
  //   fprintf(stderr,"(%d,%d,%d) ",    images[3*nm-3*i-3],    images[3*nm-3*i-2],        images[3*nm-3*i-1]);
  tot++;
  

  //  printf("%d \n",tot);

坐标还在。我只是在尝试这两种纹理是否正常。

【问题讨论】：

为什么texture 是全球性的？按原样获取此代码。不能是全球性的吗？很抱歉没有更好的答案。 【参考方案1】：

试试这个：

#include <GL/glut.h>
#include <vector>

float rX=0, rY=0, rZ=0;
float dZ =-2.0;
static void key(unsigned char key, int x, int y)

    switch (key) 
    
    case 27 : 
    case 'q':
        exit(0);
        break;

    case '+':    
        break;

    case 'x':
        rX= rX + 0.5;
        break;

    case  'X':
        rX= rX - 0.5;
        break;  

    case 'y':
        rY= rY + 0.5;
        break;   

    case 'Y':
        rY= rY - 0.5;    
        break;

    case 'z':
        rZ= rZ + 0.5;    
        break;

    case 'Z':
        rZ= rZ - 0.5;
        break;         

    case 'd':
        dZ = dZ+100.0;// horizontal movement to the left
        break;

    case 'D':
        dZ = dZ-100.0;// horizontal movement to the right
        break;
    


void showPictureW()

    //face 1
    glBegin( GL_TRIANGLES );
    glTexCoord2d(1.0,1.0); glVertex3d(-1.0,1.0,-2.0);
    glTexCoord2d(1.0,0.0); glVertex3d(-1,-1.0,-2.0);  //1 -1
    glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,-2.0); //-1 -1
    //face 2
    glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,-2.0);
    glTexCoord2d(0.0,1.0); glVertex3d(1.0,1.0,-2.0);
    glTexCoord2d(1.0,1.0); glVertex3d(-1.0,1.0,-2.0);  //1 -1   
    glEnd();


void showPictureR()

    //face 1
    glBegin( GL_TRIANGLES );
    glTexCoord2d(1.0,1.0); glVertex3d(-1.0,1.0,-2.0);
    glTexCoord2d(1.0,0.0); glVertex3d(-1,-1.0,-2.0);  //1 -1
    glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,-2.0); //-1 -1
    //face 2
    glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,0.0);
    glTexCoord2d(0.0,1.0); glVertex3d(1.0,3.0,-2.0);
    glTexCoord2d(1.0,1.0); glVertex3d(-1.0,3.0,-2.0);  //1 -1   
    glEnd();


GLuint texture1 = 0;
GLuint texture2 = 0;
static void display(void)

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    double w = glutGet( GLUT_WINDOW_WIDTH );
    double h = glutGet( GLUT_WINDOW_HEIGHT );
    double ar = w / h;
    glFrustum(-ar, ar, -1.0, 1.0, 1.0, 100.0);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity() ;

    glEnable( GL_TEXTURE_2D );
    glColor3ub(255,255,255);

    glBindTexture( GL_TEXTURE_2D, texture1 );
    glPushMatrix();
    glTranslated(0,0,0);
    glRotated(rX,0,0,1);
    glRotated(rY,0,1,0);
    glRotated(rZ,1,0,0);
    showPictureW();
    glPopMatrix();

    glBindTexture( GL_TEXTURE_2D, texture2 );
    glPushMatrix();
    glTranslated(0,0,0);
    glRotated(rX,0,0,1);
    glRotated(rY,1,1,0);
    glRotated(rZ,1,0,0);
    showPictureR();
    glPopMatrix();

    glutSwapBuffers();


static void idle(void)

    glutPostRedisplay();


GLuint LoadTexture(int width, int height, unsigned int component )

    std::vector< unsigned char > image( width*height*3 );
    for(int i=0;i< width*height*3; i += 3)
    
        image[i+0] = 0;
        image[i+1] = 0;
        image[i+2] = 0;
        image[i+component] = rand() % 255;
      

    bool wrap = true;
    GLuint texture = 0;
    glGenTextures( 1, &texture );
    // select our current texture
    glBindTexture( GL_TEXTURE_2D, texture );
    // select modulate to mix texture with color for shading
    glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
    // when texture area is small, bilinear filter the closest mipmap
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST );
    // when texture area is large, bilinear filter the first mipmap
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
    // if wrap is true, the texture wraps over at the edges (repeat)
    //       ... false, the texture ends at the edges (clamp)
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap ? GL_REPEAT : GL_CLAMP );
    glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,wrap ? GL_REPEAT : GL_CLAMP );
    // build our texture mipmaps
    gluBuild2DMipmaps( GL_TEXTURE_2D, GL_RGB, width, height, GL_RGB, GL_UNSIGNED_BYTE, &image[0] );

    return texture;


int main(int argc, char *argv[])

    glutInit(&argc, argv);
    glutInitWindowSize(640,480);
    glutInitWindowPosition(10,10);
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);

    glutCreateWindow("FreeGLUT Shapes");
    glutDisplayFunc(display);
    glutKeyboardFunc(key);
    glutIdleFunc(idle);

    glClearColor(1,1,1,1);
    glEnable(GL_CULL_FACE);
    glCullFace(GL_BACK);

    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);

    glEnable(GL_LIGHT0);
    glEnable(GL_NORMALIZE);
    glEnable(GL_COLOR_MATERIAL);
    glEnable(GL_LIGHTING);

    const GLfloat light_ambient[]  =  0.0f, 0.0f, 0.0f, 1.0f ;
    const GLfloat light_diffuse[]  =  1.0f, 1.0f, 1.0f, 1.0f ;
    const GLfloat light_specular[] =  1.0f, 1.0f, 1.0f, 1.0f ;
    const GLfloat light_position[] =  2.0f, 5.0f, 5.0f, 0.0f ;
    glLightfv(GL_LIGHT0, GL_AMBIENT,  light_ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE,  light_diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, light_specular);
    glLightfv(GL_LIGHT0, GL_POSITION, light_position);

    const GLfloat mat_ambient[]    =  0.7f, 0.7f, 0.7f, 1.0f ;
    const GLfloat mat_diffuse[]    =  0.8f, 0.8f, 0.8f, 1.0f ;
    const GLfloat mat_specular[]   =  1.0f, 1.0f, 1.0f, 1.0f ;
    const GLfloat high_shininess[] =  100.0f ;
    glMaterialfv(GL_FRONT, GL_AMBIENT,   mat_ambient);
    glMaterialfv(GL_FRONT, GL_DIFFUSE,   mat_diffuse);
    glMaterialfv(GL_FRONT, GL_SPECULAR,  mat_specular);
    glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess);

    srand( 0 );
    texture1 = LoadTexture( 256, 256, 0 );
    texture2 = LoadTexture( 256, 256, 1 );

    glutMainLoop();

    return EXIT_SUCCESS;

【讨论】：

输出是一个带有颗粒状红色纹理的正方形，我认为这是因为texture1 = LoadTexture( 256, 256, 0 ); 和texture2 = LoadTexture( 256, 256, 1 );。是对的吗？如果我要使用 .ppm 图像，我在哪里指定呢？我的任务是建造一所房子，因此是盒子（墙）和三角形（屋顶）。我希望这反映在我发布的代码中。修改 LoadTexture() 以加载 PPM。重要的部分是使用两个纹理对象，每个纹理一个。并且不生成/重新加载纹理每一帧。我已经从我的原始代码修改了LoadTexture()，它运行良好。将其合并到您的代码中。谢谢:)

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