【纹理贴图】纹理贴图没有颜色，而且出现条纹是为什么？

代码如下：
#include <GL/glut.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#define WindowWidth 400
#define WindowHeight 400
#define WindowTitle "OpenGL纹理测试"
#define BM_Header_Length 54
#ifndef GL_EXT_bgra
#define GL_EXT_bgra 1
#define GL_BGR_EXT 0x80E0
#define GL_BGRA_EXT 0x80E1
#define GLEW_EXT_bgra GLEW_GET_VAR(__GLEW_EXT_bgra)
#endif
// 写入像素数据
void grab(void)
{
FILE* pDummyFile;
FILE* pWritingFile;
GLubyte* pPixelData;
GLubyte BMP_Header[54];
GLint i, j;
GLint PixelDataLength;
// 计算像素数据的实际长度
i = WindowWidth * 3; // 得到每一行的像素数据长度
while( i%4 != 0 ) // 补充数据，直到 i 是的倍数
++i; // 本来还有更快的算法，
PixelDataLength = i * WindowHeight;
// 分配内存和打开文件
pPixelData = (GLubyte*)malloc(PixelDataLength);
if( pPixelData == 0 )
exit(0);
pDummyFile = fopen("D:\\计算机图形学\\OpenGL Projects\\OpenGL Programming Guide\\TestTexture1\\dummy.bmp", "rb");
if( pDummyFile == 0 )
exit(0);
pWritingFile = fopen("D:\\计算机图形学\\OpenGL Projects\\OpenGL Programming Guide\\TestTexture1\\grab.bmp", "wb");
if( pWritingFile == 0 )
exit(0);
// 读取像素
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
glReadPixels(0, 0, WindowWidth, WindowHeight,
GL_BGR_EXT, GL_UNSIGNED_BYTE, pPixelData);
// 把 dummy.bmp 的文件头复制为新文件的文件头
fread(BMP_Header, sizeof(BMP_Header), 1, pDummyFile);
fwrite(BMP_Header, sizeof(BMP_Header), 1, pWritingFile) ;
fseek(pWritingFile, 0x0012, SEEK_SET);
i = WindowWidth;
j = WindowHeight;
fwrite(&i, sizeof(i), 1, pWritingFile) ;
fwrite(&j, sizeof(j), 1, pWritingFile) ;
// 写入像素数据
fseek(pWritingFile, 0, SEEK_END);
fwrite(pPixelData, PixelDataLength, 1, pWritingFile) ;
// 释放内存和关闭文件
fclose(pDummyFile);
fclose(pWritingFile);
free(pPixelData);
}
int power_of_two(int n)
{
if( n <= 0 )
return 0;
return (n & (n-1)) == 0;
}
GLuint load_texture(const char* file_name)
{
GLint width, height, total_bytes;
GLubyte* pixels = 0;
GLint last_texture_ID;
GLuint texture_ID = 0;
// 打开文件，如果失败，返回
FILE* pFile = fopen(file_name, "rb");
if( pFile == 0 )
return 0;
// 读取文件中图象的宽度和高度
fseek(pFile, 0x0012, SEEK_SET);
fread(&width, 4, 1, pFile);
width = abs(width);
fread(&height, 4, 1, pFile);
height = abs(height);
fseek(pFile, 54, SEEK_SET);
// 计算每行像素所占字节数，并根据此数据计算总像素字节数
{
GLint line_bytes = width * 3;
while( line_bytes % 4 != 0 )
++line_bytes;
total_bytes = line_bytes * height;
}
printf("width-->%d\n",width);
printf("height-->%d\n",height);
printf("total bytes-->%d\n",total_bytes);
// 根据总像素字节数分配内存
pixels = (GLubyte*)malloc(total_bytes);
if( pixels == 0 )
{
fclose(pFile);
return 0;
}
// 读取像素数据
if( fread(pixels, total_bytes, 1, pFile) <= 0 )
{
free(pixels);
fclose(pFile);
return 0;
}
{
GLint max;
glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max);
if( !power_of_two(width)
|| !power_of_two(height)
|| width > max
|| height > max )
{
const GLint new_width = 256;
const GLint new_height = 256; // 规定缩放后新的大小为边长的正方形
GLint new_line_bytes, new_total_bytes;
GLubyte* new_pixels = 0;
new_line_bytes = new_width * 3;
while( new_line_bytes % 4 != 0 )
++new_line_bytes;
new_total_bytes = new_line_bytes * new_height;
// 分配内存
new_pixels = (GLubyte*)malloc(new_total_bytes);
if( new_pixels == 0 )
{
free(pixels);
fclose(pFile);
return 0;
}
// 进行像素缩放
gluScaleImage(GL_RGB,
width, height, GL_UNSIGNED_BYTE, pixels,
new_width, new_height, GL_UNSIGNED_BYTE, new_pixels);
// 释放原来的像素数据，把 p ixels 指向新的像素数据，并重新设置 width 和 height
free(pixels);
pixels = new_pixels;
width = new_width;
height = new_height;
}
}
// 分配一个新的纹理编号
glGenTextures(1, &texture_ID);
if( texture_ID == 0 )
{
free(pixels);
fclose(pFile);
return 0;
}
glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_texture_ID);
glBindTexture(GL_TEXTURE_2D, texture_ID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0,
GL_BGR_EXT, GL_UNSIGNED_BYTE, pixels);
glBindTexture(GL_TEXTURE_2D, last_texture_ID);
free(pixels);
return texture_ID;
}
GLuint texGround;
GLuint texWall;
void display (void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity ();
gluPerspective(75, 1, 1, 21);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity ();
gluLookAt(1, 5, 5, 0, 0, 0, 0, 0, 1);
glBindTexture(GL_TEXTURE_2D, texGround);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-8.0f, -8.0f, 0.0f) ;
glTexCoord2f(0.0f, 5.0f); glVertex3f(-8.0f, 8.0f, 0.0f) ;
glTexCoord2f(5.0f, 5.0f); glVertex3f(8.0f, 8.0f, 0.0f) ;
glTexCoord2f(5.0f, 0.0f); glVertex3f(8.0f, -8.0f, 0.0f) ;
glEnd();
glBindTexture(GL_TEXTURE_2D, texWall) ;printf("flag\n");
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-6.0f, -3.0f, 0.0f) ;
glTexCoord2f(0.0f, 1.0f); glVertex3f(-6.0f, -3.0f, 1.5f) ;
glTexCoord2f(5.0f, 1.0f); glVertex3f(6.0f, -3.0f, 1.5f) ;
glTexCoord2f(5.0f, 0.0f); glVertex3f(6.0f, -3.0f, 0.0f) ;
glEnd();
glRotatef(-90, 0, 0, 1);
glBegin(GL_QUADS);
glTexCoord2f(0.0f, 0.0f); glVertex3f(-6.0f, -3.0f, 0.0f) ;
glTexCoord2f(0.0f, 1.0f); glVertex3f(-6.0f, -3.0f, 1.5f) ;
glTexCoord2f(5.0f, 1.0f); glVertex3f(6.0f, -3.0f, 1.5f) ;
glTexCoord2f(5.0f, 0.0f); glVertex3f(6.0f, -3.0f, 0.0f) ;
glEnd();
glutSwapBuffers();
grab() ;
}
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowPosition(100, 100);
glutInitWindowSize(WindowWidth, WindowHeight);
glutCreateWindow(WindowTitle);
glEnable(GL_DEPTH_TEST);
glEnable(GL_TEXTURE_2D);
glutDisplayFunc(&display );
texGround = load_texture("D:\\计算机图形学\\OpenGL Projects\\OpenGL Programming Guide\\TestTexture1\\ground.bmp");
printf("ground--%d\n",texGround);
texWall = load_texture("D:\\计算机图形学\\OpenGL Projects\\OpenGL Programming Guide\\TestTexture1\\wall.bmp");
printf("wall--%d\n",texWall);
glutMainLoop();
return 0;
}