Text_6.rar_纹理映射

/* ... Aug 19th: Added support for runlength encoding - changed some stuff around to make this possible. Works well :) Sept 7th: Improved error trapping and recovery. Oct 22nd: Major source clearout & Can compress the image using S3_TC algorithm if the driver supports it. Nov 10th: 'Settled' version of the code - traps for nearly all errors - added a LoadAndBind function for even lazier people :) TGA_NO_PASS was added in case you need to load an image and pass it yourself. Finally exorcised all the paletted texture code... */ #include <windows.h> #include <GL\glu.h> #include <stdio.h> //#include <mem.h> #include "tgaload.h" /* Extension Management */ PFNGLCOMPRESSEDTEXIMAGE2DARBPROC glCompressedTexImage2DARB = NULL; PFNGLGETCOMPRESSEDTEXIMAGEARBPROC glGetCompressedTexImageARB = NULL; /* Default support - lets be optimistic! */ bool tgaCompressedTexSupport = true; void tgaGetExtensions ( void ) { glCompressedTexImage2DARB = ( PFNGLCOMPRESSEDTEXIMAGE2DARBPROC ) wglGetProcAddress ( "glCompressedTexImage2DARB" ); glGetCompressedTexImageARB = ( PFNGLGETCOMPRESSEDTEXIMAGEARBPROC ) wglGetProcAddress ( "glGetCompressedTexImageARB" ); if ( glCompressedTexImage2DARB == NULL || glGetCompressedTexImageARB == NULL ) tgaCompressedTexSupport = false; } void tgaSetTexParams ( unsigned int min_filter, unsigned int mag_filter, unsigned int application ) { glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, min_filter ); glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, mag_filter ); glTexEnvf ( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, application ); } unsigned char *tgaAllocMem ( tgaHeader_t info ) { unsigned char *block; block = (unsigned char*) malloc ( info.bytes ); if ( block == NULL ) return 0; memset ( block, 0x00, info.bytes ); return block; } void tgaPutPacketTuples ( image_t *p, unsigned char *temp_colour, int &current_byte ) { if ( p->info.components == 3 ) { p->data[current_byte] = temp_colour[2]; p->data[current_byte+1] = temp_colour[1]; p->data[current_byte+2] = temp_colour[0]; current_byte += 3; } if ( p->info.components == 4 ) // Because its BGR(A) not (A)BGR :( { p->data[current_byte] = temp_colour[2]; p->data[current_byte+1] = temp_colour[1]; p->data[current_byte+2] = temp_colour[0]; p->data[current_byte+3] = temp_colour[3]; current_byte += 4; } } void tgaGetAPacket ( int &current_byte, image_t *p, FILE *file ) { unsigned char packet_header; int run_length; unsigned char temp_colour[4] = { 0x00, 0x00, 0x00, 0x00 }; fread ( &packet_header, ( sizeof ( unsigned char )), 1, file ); run_length = ( packet_header&0x7F ) + 1; if ( packet_header&0x80 ) // RLE packet { fread ( temp_colour, ( sizeof ( unsigned char )* p->info.components ), 1, file ); if ( p->info.components == 1 ) // Special optimised case :) { memset ( p->data + current_byte, temp_colour[0], run_length ); current_byte += run_length; } else for ( int i = 0; i < run_length; i++ ) tgaPutPacketTuples ( p, temp_colour, current_byte ); } if ( !( packet_header&0x80 )) // RAW packet { for ( int i = 0; i < run_length; i++ ) { fread ( temp_colour, ( sizeof ( unsigned char )* p->info.components ), 1, file ); if ( p->info.components == 1 ) { memset ( p->data + current_byte, temp_colour[0], run_length ); current_byte += run_length; } else tgaPutPacketTuples ( p, temp_colour, current_byte ); } } } void tgaGetPackets ( image_t *p, FILE *file ) { int current_byte = 0; while ( current_byte < p->info.bytes ) tgaGetAPacket ( current_byte, p, file ); } void tgaGetImageData ( image_t *p, FILE *file ) { unsigned char temp; p->data = tgaAllocMem ( p->info ); /* Easy unRLE image */ if ( p->info.image_type == 1 || p->info.image_type == 2 || p->info.image_type == 3 ) { fread ( p->data, sizeof (unsigned char), p->info.bytes, file ); /* Image is stored as BGR(A), make it RGB(A) */ for (int i = 0; i < p->info.bytes; i += p->info.components ) { temp = p->data[i]; p->data[i] = p->data[i + 2]; p->data[i + 2] = temp; } } /* RLE compressed image */ if ( p->info.image_type == 9 || p->info.image_type == 10 ) tgaGetPackets ( p, file ); } void tgaUploadImage ( image_t *p, tgaFLAG mode ) { /* Determine TGA_LOWQUALITY internal format This directs OpenGL to upload the textures at half the bit precision - saving memory */ GLenum internal_format = p->info.tgaColourType; if ( mode&TGA_LOW_QUALITY ) { switch ( p->info.tgaColourType ) { case GL_RGB : internal_format = GL_RGB4; break; case GL_RGBA : internal_format = GL_RGBA4; break; case GL_LUMINANCE : internal_format = GL_LUMINANCE4; break; case GL_ALPHA : internal_format = GL_ALPHA4; break; } } /* Let OpenGL decide what the best compressed format is each case. */ if ( mode&TGA_COMPRESS && tgaCompressedTexSupport ) { switch ( p->info.tgaColourType ) { case GL_RGB : internal_format = GL_COMPRESSED_RGB_ARB; break; case GL_RGBA : internal_format = GL_COMPRESSED_RGBA_ARB; break; case GL_LUMINANCE : internal_format = GL_COMPRESSED_LUMINANCE_ARB; break; case GL_ALPHA : internal_format = GL_COMPRESSED_ALPHA_ARB; break; } } /* Pass OpenGL Texture Image */ if ( !( mode&TGA_NO_MIPMAPS )) gluBuild2DMipmaps ( GL_TEXTURE_2D, internal_format, p->info.width, p->info.height, p->info.tgaColourType, GL_UNSIGNED_BYTE, p->data ); else glTexImage2D ( GL_TEXTURE_2D, 0, internal_format, p->info.width, p->info.height, 0, p->info.tgaColourType, GL_UNSIGNED_BYTE, p->data ); } void tgaFree ( image_t *p ) { if ( p->data != NULL ) free ( p->data ); } void tgaChecker ( image_t *p ) { unsigned char TGA_CHECKER[16384]; unsigned char *pointer; // 8bit image p->info.image_type = 3; p->info.width = 128; p->info.height = 128; p->info.pixel_depth = 8; // Set some stats p->info.components = 1; p->info.bytes = p->info.width * p->info.height * p->info.components; pointer = TGA_CHECKER; for ( int j = 0; j < 128; j++ ) { for ( int i = 0; i < 128; i++ ) { if ((i ^ j) & 0x10 ) pointer[0] = 0x00; else pointer[0] = 0xff; pointer ++; } } p->data = TGA_CHECKER; glTexImage2D ( GL_TEXTURE_2D, 0, GL_LUMINANCE4, p->info.width, p->info.height, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, p->data ); /* Should we free? I dunno. The scope of TGA_CHECKER _should_ be local, so it probably gets destroyed automatically when the function completes... */ // tgaFree ( p ); } void tgaError ( char *error_string, char *file_name, FILE *file, image_t *p ) { printf ( "%s - %s\n", error_string, file_name ); tgaFree ( p ); fclose ( file ); tgaChecker ( p ); } void tgaGetImageHeader ( FILE *file, tgaHeader_t *info ) { /* Stupid byte alignment means that we have to fread each field individually. I tried splitting tgaHeader into 3 structures, no matter how you arrange them, colour_map_entry_size comes out as 2 bytes instead