我修改了原始代码（previous post）以使用两个纹理。他们在这里：
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include "support.h"
using namespace std;
GLuint *images;
GLubyte *image;
GLuint texture1=0;
GLuint texture2=0;
GLuint LoadTexture(int width, int height, char *fName);
int n=200;
int m=200;
void showPictureW();
void showPictureR();
float rX=0;
float rY=0;
float rZ=0;
float tX=0;
float tY=0;
float tZ=-3.5;
float nr = -5.0;
float fr = -4.0;
float tpx = 1.0;
float tpy = 1.0;
float btx = -1.0;
float bty = -1.0;
float dZ =-2.0;
void showPictureW()
{
/* clear all pixels */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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);
glTexCoord2d(0.0,0.0); glVertex3d(1.0,-1.0,-2.0);
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);
glEnd();
}
void showPictureR()
{
//clear all pixels
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3d(1,1,1);
//face 1
glBegin( GL_POLYGON );
glTexCoord2d(1.0,1.0); glVertex3d(-1.2,1.0,-2.0);
glTexCoord2d(1.0,0.0); glVertex3d(0.0,1.0,-2.0);
glTexCoord2d(0.0,0.0); glVertex3d(0.0,2.0,-2.0);
glEnd();
//face 2
glBegin( GL_POLYGON );
glTexCoord2d(0.0,0.0); glVertex3d(0.0,2.0,-2.0);
glTexCoord2d(0.0,1.0); glVertex3d(0.0,1.0,-2.0);
glTexCoord2d(1.0,1.0); glVertex3d(1.2,1.0,-2.0);
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() ;
}
static void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3d(1,0,0);
glEnable( GL_TEXTURE_2D );
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,0,1,0);
glRotated(rZ,1,0,0);
showPictureR();
glPopMatrix();
glutSwapBuffers();
}
static void key(unsigned char key, int x, int y)
{
switch (key)
{
case 27 :
case 'q':
exit(0);
break;
case '+':
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);
texture1 = LoadTexture( 200, 200, "wall.ppm" );
texture2 = LoadTexture( 200, 200, "roof.ppm" );
glutMainLoop();
return EXIT_SUCCESS;
}
GLuint LoadTexture(int width, int height, 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);
nm = n*m;
images = new GLuint[3*sizeof(GLuint)*nm];
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++)
{
tot++;
}
image = new BYTE[width*height*3*sizeof(BYTE)];
int nmOne = width*height;
for(int i=0;i<nmOne*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;
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, 3, width, height,
GL_RGB, GL_UNSIGNED_BYTE, image );
return texture;
}
我的问题是它不会同时加载两个纹理。我一次尝试使用一个，他们没事。但是使用上面的代码只会出现第二个纹理（“roof.ppm”）。我在另一个post中找到了下面的代码，这似乎与我的问题非常相似，但我不确定如何使用它。
void DrawFrame()
{
...
glMatrixMode( GL_PROJECTION );
glLoadIdentity();
gluOrtho2D(0, this.Width, 0, this.Height);
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
// "camera" transform(s)
foreach object
{
glPushMatrix();
// per-object matrix transform(s)
// draw object
glPopMatrix();
}
}
答案 0 :(得分：4)
你打电话
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
在您的showPictureW和showPictureR两个函数中，所以最后只能看到这些调用的最后效果并不会让您感到惊讶。