1.1 --- a/main.c	Tue Jan 09 08:15:12 2018 +0200
     1.2 +++ b/main.c	Tue Jan 09 08:43:16 2018 +0200
     1.3 @@ -20,6 +20,9 @@
     1.4  void reshape(int x, int y);
     1.5  void keyb(unsigned char key, int x, int y);
     1.6  void gen_image(unsigned char *pixels, int xsz, int ysz);
     1.7 +unsigned char *load_compressed_image(const char *fname, int *cszptr, int *xszptr, int *yszptr);
     1.8 +int dump_compressed_image(const char *fname, unsigned char *data, int size, int w, int h);
     1.9 +void print_compressed_formats(void);
    1.10  
    1.11  unsigned int tex, comp_tex;
    1.12  const char *texfile;
    1.13 @@ -57,36 +60,14 @@
    1.14  	int ysz = 512;
    1.15  	int is_comp = 0;
    1.16  	int comp_size = 0;
    1.17 -	int start, tmp;
    1.18 -	FILE *fp;
    1.19 +	int tmp;
    1.20 +
    1.21 +	print_compressed_formats();
    1.22  
    1.23  	if(texfile) {
    1.24 -		if(!(fp = fopen(texfile, "rb"))) {
    1.25 -			fprintf(stderr, "failed to open compressed texture file: %s: %s\n", texfile, strerror(errno));
    1.26 +		if(!(pixels = load_compressed_image(texfile, &comp_size, &xsz, &ysz))) {
    1.27  			return -1;
    1.28  		}
    1.29 -
    1.30 -		if(fread(&xsz, sizeof xsz, 1, fp) < 1 || fread(&ysz, sizeof ysz, 1, fp) < 1) {
    1.31 -			fprintf(stderr, "failed to read compressed texture file header: %s: %s\n", texfile, strerror(errno));
    1.32 -			fclose(fp);
    1.33 -			return -1;
    1.34 -		}
    1.35 -		start = ftell(fp);
    1.36 -		fseek(fp, 0, SEEK_END);
    1.37 -		comp_size = ftell(fp) - start;
    1.38 -		fseek(fp, start, SEEK_SET);
    1.39 -
    1.40 -		if(!(pixels = malloc(comp_size))) {
    1.41 -			abort();
    1.42 -		}
    1.43 -		if(fread(pixels, 1, comp_size, fp) < comp_size) {
    1.44 -			fprintf(stderr, "failed to read compressed texture file: %s: %s\n", texfile, strerror(errno));
    1.45 -			fclose(fp);
    1.46 -			free(pixels);
    1.47 -			return -1;
    1.48 -		}
    1.49 -		fclose(fp);
    1.50 -
    1.51  		printf("loaded compressed texture file: %s (%dx%d)\n", texfile, xsz, ysz);
    1.52  
    1.53  	} else {
    1.54 @@ -101,17 +82,7 @@
    1.55  		}
    1.56  		printf("compressed texture is %d bytes (uncompressed was: %d)\n", comp_size, xsz * ysz * 3);
    1.57  
    1.58 -		/* dump compressed texture */
    1.59 -		if(!(fp = fopen("compressed_texture", "wb"))) {
    1.60 -			fprintf(stderr, "failed to open compressed texture dump file: %s\n", strerror(errno));
    1.61 -		} else {
    1.62 -			if(fwrite(&xsz, sizeof xsz, 1, fp) < 1 ||
    1.63 -					fwrite(&ysz, sizeof ysz, 1, fp) < 1 ||
    1.64 -					fwrite(pixels, 1, comp_size, fp) < comp_size) {
    1.65 -				fprintf(stderr, "failed to dump compressed texture: %s\n", strerror(errno));
    1.66 -			}
    1.67 -			fclose(fp);
    1.68 -		}
    1.69 +		dump_compressed_image("compressed_texture", pixels, comp_size, xsz, ysz);
    1.70  	}
    1.71  
    1.72  	glGenTextures(1, &tex);
    1.73 @@ -143,9 +114,9 @@
    1.74  
    1.75  	if(memcmp(pixels, buf, comp_size) != 0) {
    1.76  		fprintf(stderr, "submitted and retrieved pixel data differ!\n");
    1.77 -		return -1;
    1.78 +	} else {
    1.79 +		printf("submitted and retrieved sizes match (%d bytes)\n", comp_size);
    1.80  	}
    1.81 -	printf("submitted and retrieved sizes match (%d bytes)\n", comp_size);
    1.82  	free(buf);
    1.83  	free(pixels);
    1.84  
    1.85 @@ -229,3 +200,122 @@
    1.86  		}
    1.87  	}
    1.88  }
    1.89 +
    1.90 +unsigned char *load_compressed_image(const char *fname, int *cszptr, int *xszptr, int *yszptr)
    1.91 +{
    1.92 +	unsigned char *pixels;
    1.93 +	long start, comp_size;
    1.94 +	int xsz, ysz;
    1.95 +	FILE *fp;
    1.96 +
    1.97 +	if(!(fp = fopen(texfile, "rb"))) {
    1.98 +		fprintf(stderr, "failed to open compressed texture file: %s: %s\n", texfile, strerror(errno));
    1.99 +		return 0;
   1.100 +	}
   1.101 +
   1.102 +	if(fread(&xsz, sizeof xsz, 1, fp) < 1 || fread(&ysz, sizeof ysz, 1, fp) < 1) {
   1.103 +		fprintf(stderr, "failed to read compressed texture file header: %s: %s\n", texfile, strerror(errno));
   1.104 +		fclose(fp);
   1.105 +		return 0;
   1.106 +	}
   1.107 +	start = ftell(fp);
   1.108 +	fseek(fp, 0, SEEK_END);
   1.109 +	comp_size = ftell(fp) - start;
   1.110 +	fseek(fp, start, SEEK_SET);
   1.111 +
   1.112 +	if(!(pixels = malloc(comp_size))) {
   1.113 +		perror("failed to allocate pixel buffer");
   1.114 +		return 0;
   1.115 +	}
   1.116 +	if(fread(pixels, 1, comp_size, fp) < comp_size) {
   1.117 +		fprintf(stderr, "failed to read compressed texture file: %s: %s\n", texfile, strerror(errno));
   1.118 +		fclose(fp);
   1.119 +		free(pixels);
   1.120 +		return 0;
   1.121 +	}
   1.122 +	fclose(fp);
   1.123 +
   1.124 +	*cszptr = comp_size;
   1.125 +	*xszptr = xsz;
   1.126 +	*yszptr = ysz;
   1.127 +	return pixels;
   1.128 +}
   1.129 +
   1.130 +int dump_compressed_image(const char *fname, unsigned char *data, int size, int w, int h)
   1.131 +{
   1.132 +	FILE *fp;
   1.133 +
   1.134 +	if(!(fp = fopen(fname, "wb"))) {
   1.135 +		fprintf(stderr, "failed to open compressed texture dump file: %s: %s\n", fname, strerror(errno));
   1.136 +		return -1;
   1.137 +	}
   1.138 +
   1.139 +	if(fwrite(&w, sizeof w, 1, fp) < 1 ||
   1.140 +			fwrite(&h, sizeof h, 1, fp) < 1 ||
   1.141 +			fwrite(data, 1, size, fp) < size) {
   1.142 +		fprintf(stderr, "failed to dump compressed texture: %s\n", strerror(errno));
   1.143 +	}
   1.144 +	fclose(fp);
   1.145 +	return 0;
   1.146 +}
   1.147 +
   1.148 +const char *fmtstr(int fmt)
   1.149 +{
   1.150 +	switch(fmt) {
   1.151 +	case 0x86b0: return "GL_COMPRESSED_RGB_FXT1_3DFX";
   1.152 +	case 0x86b1: return "GL_COMPRESSED_RGBA_FXT1_3DFX";
   1.153 +	case 0x8dbb: return "GL_COMPRESSED_RED_RGTC1";
   1.154 +	case 0x8dbc: return "GL_COMPRESSED_SIGNED_RED_RGTC1";
   1.155 +	case 0x8dbd: return "GL_COMPRESSED_RG_RGTC2";
   1.156 +	case 0x8dbe: return "GL_COMPRESSED_SIGNED_RG_RGTC2";
   1.157 +	case 0x8e8c: return "GL_COMPRESSED_RGBA_BPTC_UNORM";
   1.158 +	case 0x8e8d: return "GL_COMPRESSED_SRGB_ALPHA_BPTC_UNORM";
   1.159 +	case 0x8e8e: return "GL_COMPRESSED_RGB_BPTC_SIGNED_FLOAT";
   1.160 +	case 0x8e8f: return "GL_COMPRESSED_RGB_BPTC_UNSIGNED_FLOAT";
   1.161 +	case 0x9274: return "GL_COMPRESSED_RGB8_ETC2";
   1.162 +	case 0x9275: return "GL_COMPRESSED_SRGB8_ETC2";
   1.163 +	case 0x9276: return "GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2";
   1.164 +	case 0x9277: return "GL_COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_ETC2";
   1.165 +	case 0x9278: return "GL_COMPRESSED_RGBA8_ETC2_EAC";
   1.166 +	case 0x9279: return "GL_COMPRESSED_SRGB8_ALPHA8_ETC2_EAC";
   1.167 +	case 0x9270: return "GL_COMPRESSED_R11_EAC";
   1.168 +	case 0x9271: return "GL_COMPRESSED_SIGNED_R11_EAC";
   1.169 +	case 0x9272: return "GL_COMPRESSED_RG11_EAC";
   1.170 +	case 0x9273: return "GL_COMPRESSED_SIGNED_RG11_EAC";
   1.171 +	case 0x83F0: return "GL_COMPRESSED_RGB_S3TC_DXT1_EXT";
   1.172 +	case 0x83F1: return "GL_COMPRESSED_RGBA_S3TC_DXT1_EXT";
   1.173 +	case 0x83F2: return "GL_COMPRESSED_RGBA_S3TC_DXT3_EXT";
   1.174 +	case 0x83F3: return "GL_COMPRESSED_RGBA_S3TC_DXT5_EXT";
   1.175 +	case 0x8C48: return "GL_COMPRESSED_SRGB_EXT";
   1.176 +	case 0x8C49: return "GL_COMPRESSED_SRGB_ALPHA_EXT";
   1.177 +	case 0x8C4A: return "GL_COMPRESSED_SLUMINANCE_EXT";
   1.178 +	case 0x8C4B: return "GL_COMPRESSED_SLUMINANCE_ALPHA_EXT";
   1.179 +	case 0x8C4C: return "GL_COMPRESSED_SRGB_S3TC_DXT1_EXT";
   1.180 +	case 0x8C4D: return "GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT1_EXT";
   1.181 +	case 0x8C4E: return "GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT3_EXT";
   1.182 +	case 0x8C4F: return "GL_COMPRESSED_SRGB_ALPHA_S3TC_DXT5_EXT";
   1.183 +	default:
   1.184 +		break;
   1.185 +	}
   1.186 +	return "unknown";
   1.187 +}
   1.188 +
   1.189 +void print_compressed_formats(void)
   1.190 +{
   1.191 +	int i, num_fmt;
   1.192 +	int *fmtlist;
   1.193 +
   1.194 +	glGetIntegerv(GL_NUM_COMPRESSED_TEXTURE_FORMATS, &num_fmt);
   1.195 +	printf("%d generic compressed texture formats available:\n", num_fmt);
   1.196 +
   1.197 +	if(!(fmtlist = malloc(num_fmt * sizeof *fmtlist))) {
   1.198 +		fprintf(stderr, "failed to allocate texture formats enumeration buffer\n");
   1.199 +		return;
   1.200 +	}
   1.201 +	glGetIntegerv(GL_COMPRESSED_TEXTURE_FORMATS, fmtlist);
   1.202 +
   1.203 +	for(i=0; i<num_fmt; i++) {
   1.204 +		printf(" %05x: %s\n", fmtlist[i], fmtstr(fmtlist[i]));
   1.205 +	}
   1.206 +	free(fmtlist);
   1.207 +}