加载bmp文件方法一

- 日理万妓 2022-08-05 13:13 181阅读 0赞

第一步：定义类CMyTexture

MyTexture.h文件内容：

typedef struct _ImageRec 
    {
        unsigned short imagic;
        unsigned short type;
        unsigned short dim;
        unsigned short xsize, ysize, zsize;
        unsigned int min, max;
        unsigned int wasteBytes;
        char name[80];
        unsigned long colorMap;
        FILE *file;
        unsigned char *tmp, *tmpR, *tmpG, *tmpB;
        unsigned long rleEnd;
        unsigned int *rowStart;
        int *rowSize;
    } ImageRec;
    
    class CMyTexture  
    {
    public:
    	CMyTexture();
    	virtual ~CMyTexture();
    	void bwtorgba(unsigned char *b,unsigned char *l,int n);
    	void latorgba(unsigned char *b, unsigned char *a,unsigned char *l,int n);
    	void rgbtorgba(unsigned char *r,unsigned char *g,unsigned char *b,unsigned char *l,int n); 
    	void rgbatorgba(unsigned char *r,unsigned char *g,unsigned char *b,unsigned char *a,unsigned char *l,int n); 
    	void ConvertShort(unsigned short *array, long length); 
    	void ConvertLong(unsigned *array, long length); 
    	ImageRec * ImageOpen(const char *fileName);
    	void ImageClose(ImageRec *image); 
    	void ImageGetRow(ImageRec *image, unsigned char *buf, int y, int z); 
    	unsigned * read_texture(char *name, int *width, int *height, int *components); 
    
    };

MyTexture.cpp内容：

CMyTexture::CMyTexture()
    {
    
    }
    
    CMyTexture::~CMyTexture()
    {
    
    }
    
    void CMyTexture::bwtorgba(unsigned char *b,unsigned char *l,int n)
    {
        while(n--)
    	{
    	l[0] = *b;
    	l[1] = *b;
    	l[2] = *b;
    	l[3] = 0xff;
    	l += 4; b++;
        }
    }
    
    void CMyTexture::latorgba(unsigned char *b, unsigned char *a,unsigned char *l,int n) 
    {
        while(n--) 
    	{
    	l[0] = *b;
    	l[1] = *b;
    	l[2] = *b;
    	l[3] = *a;
    	l += 4; b++; a++;
        }
    }
    
    void CMyTexture::rgbtorgba(unsigned char *r,unsigned char *g,unsigned char *b,unsigned char *l,int n) 
    {
        while(n--) 
    	{
    	l[0] = r[0];
    	l[1] = g[0];
    	l[2] = b[0];
    	l[3] = 0xff;
    	l += 4; r++; g++; b++;
        }
    }
    
    void CMyTexture::rgbatorgba(unsigned char *r,unsigned char *g,unsigned char *b,unsigned char *a,unsigned char *l,int n) 
    {
        while(n--) 
    	{
    	l[0] = r[0];
    	l[1] = g[0];
    	l[2] = b[0];
    	l[3] = a[0];
            l += 4; r++; g++; b++; a++;
        }
    }
    
    
    void CMyTexture::ConvertShort(unsigned short *array, long length) 
    {
        unsigned b1, b2;
        unsigned char *ptr;
    
        ptr = (unsigned char *)array;
        while (length--) 
    	{
    	b1 = *ptr++;
    	b2 = *ptr++;
    	*array++ = (b1 << 8) | (b2);
        }
    }
    
    void CMyTexture::ConvertLong(unsigned *array, long length) 
    {
        unsigned b1, b2, b3, b4;
        unsigned char *ptr;
    
        ptr = (unsigned char *)array;
        while (length--) {
    	b1 = *ptr++;
    	b2 = *ptr++;
    	b3 = *ptr++;
    	b4 = *ptr++;
    	*array++ = (b1 << 24) | (b2 << 16) | (b3 << 8) | (b4);
        }
    }
    
    ImageRec * CMyTexture::ImageOpen(const char *fileName)
    {
        union {
    	int testWord;
    	char testByte[4];
        } endianTest;
        ImageRec *image;
        int swapFlag;
        int x;
    
        endianTest.testWord = 1;
        if (endianTest.testByte[0] == 1) {
    	swapFlag = 1;
        } else {
    	swapFlag = 0;
        }
    
        image = (ImageRec *)malloc(sizeof(ImageRec));
        if (image == NULL) {
    	fprintf(stderr, "Out of memory!\n");
    	exit(1);
        }
        if ((image->file = fopen(fileName, "rb")) == NULL) {
    	perror(fileName);
    	exit(1);
        }
    
        fread(image, 1, 12, image->file);
    
        if (swapFlag) {
    	ConvertShort(&image->imagic, 6);
        }
    
        image->tmp = (unsigned char *)malloc(image->xsize*256);
        image->tmpR = (unsigned char *)malloc(image->xsize*256);
        image->tmpG = (unsigned char *)malloc(image->xsize*256);
        image->tmpB = (unsigned char *)malloc(image->xsize*256);
        if (image->tmp == NULL || image->tmpR == NULL || image->tmpG == NULL ||
    	image->tmpB == NULL) {
    	fprintf(stderr, "Out of memory!\n");
    	exit(1);
        }
    
        if ((image->type & 0xFF00) == 0x0100) {
    	x = image->ysize * image->zsize * sizeof(unsigned);
    	image->rowStart = (unsigned *)malloc(x);
    	image->rowSize = (int *)malloc(x);
    	if (image->rowStart == NULL || image->rowSize == NULL) {
    	    fprintf(stderr, "Out of memory!\n");
    	    exit(1);
    	}
    	image->rleEnd = 512 + (2 * x);
    	fseek(image->file, 512, SEEK_SET);
    	fread(image->rowStart, 1, x, image->file);
    	fread(image->rowSize, 1, x, image->file);
    	if (swapFlag) {
    	    ConvertLong(image->rowStart, x/(int)sizeof(unsigned));
    	    ConvertLong((unsigned *)image->rowSize, x/(int)sizeof(int));
    	}
        } else {
    	image->rowStart = NULL;
    	image->rowSize = NULL;
        }
        return image;
    }
    
    void CMyTexture::ImageClose(ImageRec *image) 
    {
        fclose(image->file);
        free(image->tmp);
        free(image->tmpR);
        free(image->tmpG);
        free(image->tmpB);
        free(image->rowSize);
        free(image->rowStart);
        free(image);
    }
    
    void CMyTexture::ImageGetRow(ImageRec *image, unsigned char *buf, int y, int z) 
    {
        unsigned char *iPtr, *oPtr, pixel;
        int count;
    
        if ((image->type & 0xFF00) == 0x0100) {
    	fseek(image->file, (long)image->rowStart[y+z*image->ysize], SEEK_SET);
    	fread(image->tmp, 1, (unsigned int)image->rowSize[y+z*image->ysize],
    	      image->file);
    
    	iPtr = image->tmp;
    	oPtr = buf;
    	for (;;) {
    	    pixel = *iPtr++;
    	    count = (int)(pixel & 0x7F);
    	    if (!count) {
    		return;
    	    }
    	    if (pixel & 0x80) {
    		while (count--) {
    		    *oPtr++ = *iPtr++;
    		}
    	    } else {
    		pixel = *iPtr++;
    		while (count--) {
    		    *oPtr++ = pixel;
    		}
    	    }
    	}
        } else {
    	fseek(image->file, 512+(y*image->xsize)+(z*image->xsize*image->ysize),
    	      SEEK_SET);
    	fread(buf, 1, image->xsize, image->file);
        }
    }
    
    unsigned * CMyTexture::read_texture(char *name, int *width, int *height, int *components) 
    {
        unsigned *base, *lptr;
        unsigned char *rbuf, *gbuf, *bbuf, *abuf;
        ImageRec *image;
        int y;
    
        image = ImageOpen(name);
        
        if(!image)
    	return NULL;
        (*width)=image->xsize;
        (*height)=image->ysize;
        (*components)=image->zsize;
        base = (unsigned *)malloc(image->xsize*image->ysize*sizeof(unsigned));
        rbuf = (unsigned char *)malloc(image->xsize*sizeof(unsigned char));
        gbuf = (unsigned char *)malloc(image->xsize*sizeof(unsigned char));
        bbuf = (unsigned char *)malloc(image->xsize*sizeof(unsigned char));
        abuf = (unsigned char *)malloc(image->xsize*sizeof(unsigned char));
        if(!base || !rbuf || !gbuf || !bbuf)
          return NULL;
        lptr = base;
        for(y=0; y<image->ysize; y++) {
    	if(image->zsize>=4) {
    	    ImageGetRow(image,rbuf,y,0);
    	    ImageGetRow(image,gbuf,y,1);
    	    ImageGetRow(image,bbuf,y,2);
    	    ImageGetRow(image,abuf,y,3);
    	    rgbatorgba(rbuf,gbuf,bbuf,abuf,(unsigned char *)lptr,image->xsize);
    	    lptr += image->xsize;
    	} else if(image->zsize==3) {
    	    ImageGetRow(image,rbuf,y,0);
    	    ImageGetRow(image,gbuf,y,1);
    	    ImageGetRow(image,bbuf,y,2);
    	    rgbtorgba(rbuf,gbuf,bbuf,(unsigned char *)lptr,image->xsize);
    	    lptr += image->xsize;
    	} else if(image->zsize==2) {
    	    ImageGetRow(image,rbuf,y,0);
    	    ImageGetRow(image,abuf,y,1);
    	    latorgba(rbuf,abuf,(unsigned char *)lptr,image->xsize);
    	    lptr += image->xsize;
    	} else {
    	    ImageGetRow(image,rbuf,y,0);
    	    bwtorgba(rbuf,(unsigned char *)lptr,image->xsize);
    	    lptr += image->xsize;
    	}
        }
        ImageClose(image);
        free(rbuf);
        free(gbuf);
        free(bbuf);
        free(abuf);
    
        return (unsigned *) base;
    }

第二：使用：

定义函数LoadTexture(char \*fn, int t\_num)，内容如下：

int texwid, texht;
    	int texcomps;
     
    	teximage = m_Tex->read_texture(fn, &texwid, &texht, &texcomps);
    	if (!teximage)
    	{
    		MessageBox("没有找到图形文件tr.rgb","错误",MB_ICONQUESTION);
    		exit(0);
    	}
    	glBindTexture(GL_TEXTURE_2D, texture[t_num]);
    	glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    	glTexImage2D(GL_TEXTURE_2D, 0, 3, texwid, texht, 0, GL_RGBA, GL_UNSIGNED_BYTE, teximage);
    	gluBuild2DMipmaps(GL_TEXTURE_2D, 3, texwid, texht, GL_RGBA, GL_UNSIGNED_BYTE, teximage);
    
    	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); 
    	glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR); 
    
    	free(teximage);

声明参数：

CMyTexture*  m_Tex;
    	unsigned *teximage;
    	GLuint texture[6];