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• Find out CRC or CHECKSUM of RS232 data

  - by Carlos Alloatti

  I need to communicate with a RS232 device, I have no specs or information available. I send a 16 byte command and get a 16 byte result back. The last byte looks like some kind of crc or checksum, I have tried using this http://miscel.dk/MiscEl/miscelCRCandChecksum.html with no luck. Anyone can reverse engineer the crc/checksum algorithm? here is some data captured with an RS-232 monitor program: 01 80 42 00 00 00 00 00 00 00 00 00 00 00 01 B3 01 80 42 00 00 00 00 00 00 00 00 00 00 00 02 51 01 80 42 00 00 00 00 00 00 00 00 00 00 00 03 0F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 04 8C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 05 D2 01 80 42 00 00 00 00 00 00 00 00 00 00 00 06 30 01 80 42 00 00 00 00 00 00 00 00 00 00 00 07 6E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 08 2F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 09 71 01 80 42 00 00 00 00 00 00 00 00 00 00 00 0A 93 01 80 42 00 00 00 00 00 00 00 00 00 00 00 0B CD 01 80 42 00 00 00 00 00 00 00 00 00 00 00 0C 4E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 0D 10 01 80 42 00 00 00 00 00 00 00 00 00 00 00 0E F2 01 80 42 00 00 00 00 00 00 00 00 00 00 00 0F AC 01 80 42 00 00 00 00 00 00 00 00 00 00 00 10 70 01 80 42 00 00 00 00 00 00 00 00 00 00 00 11 2E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 12 CC 01 80 42 00 00 00 00 00 00 00 00 00 00 00 13 92 01 80 42 00 00 00 00 00 00 00 00 00 00 00 14 11 01 80 42 00 00 00 00 00 00 00 00 00 00 00 15 4F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 16 AD 01 80 42 00 00 00 00 00 00 00 00 00 00 00 17 F3 01 80 42 00 00 00 00 00 00 00 00 00 00 00 18 B2 01 80 42 00 00 00 00 00 00 00 00 00 00 00 19 EC 01 80 42 00 00 00 00 00 00 00 00 00 00 00 1A 0E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 1B 50 01 80 42 00 00 00 00 00 00 00 00 00 00 00 1C D3 01 80 42 00 00 00 00 00 00 00 00 00 00 00 1D 8D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 1E 6F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 1F 31 01 80 42 00 00 00 00 00 00 00 00 00 00 00 20 CE 01 80 42 00 00 00 00 00 00 00 00 00 00 00 21 90 01 80 42 00 00 00 00 00 00 00 00 00 00 00 22 72 01 80 42 00 00 00 00 00 00 00 00 00 00 00 23 2C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 24 AF 01 80 42 00 00 00 00 00 00 00 00 00 00 00 25 F1 01 80 42 00 00 00 00 00 00 00 00 00 00 00 26 13 01 80 42 00 00 00 00 00 00 00 00 00 00 00 27 4D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 28 0C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 29 52 01 80 42 00 00 00 00 00 00 00 00 00 00 00 2A B0 01 80 42 00 00 00 00 00 00 00 00 00 00 00 2B EE 01 80 42 00 00 00 00 00 00 00 00 00 00 00 2C 6D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 2D 33 01 80 42 00 00 00 00 00 00 00 00 00 00 00 2E D1 01 80 42 00 00 00 00 00 00 00 00 00 00 00 2F 8F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 30 53 01 80 42 00 00 00 00 00 00 00 00 00 00 00 31 0D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 32 EF 01 80 42 00 00 00 00 00 00 00 00 00 00 00 33 B1 01 80 42 00 00 00 00 00 00 00 00 00 00 00 34 32 01 80 42 00 00 00 00 00 00 00 00 00 00 00 35 6C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 36 8E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 37 D0 01 80 42 00 00 00 00 00 00 00 00 00 00 00 38 91 01 80 42 00 00 00 00 00 00 00 00 00 00 00 39 CF 01 80 42 00 00 00 00 00 00 00 00 00 00 00 3A 2D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 3B 73 01 80 42 00 00 00 00 00 00 00 00 00 00 00 3C F0 01 80 42 00 00 00 00 00 00 00 00 00 00 00 3D AE 01 80 42 00 00 00 00 00 00 00 00 00 00 00 3E 4C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 3F 12 01 80 42 00 00 00 00 00 00 00 00 00 00 00 40 AB 01 80 42 00 00 00 00 00 00 00 00 00 00 00 41 F5 01 80 42 00 00 00 00 00 00 00 00 00 00 00 42 17 01 80 42 00 00 00 00 00 00 00 00 00 00 00 43 49 01 80 42 00 00 00 00 00 00 00 00 00 00 00 44 CA 01 80 42 00 00 00 00 00 00 00 00 00 00 00 45 94 01 80 42 00 00 00 00 00 00 00 00 00 00 00 46 76 01 80 42 00 00 00 00 00 00 00 00 00 00 00 47 28 01 80 42 00 00 00 00 00 00 00 00 00 00 00 48 69 01 80 42 00 00 00 00 00 00 00 00 00 00 00 49 37 01 80 42 00 00 00 00 00 00 00 00 00 00 00 4A D5 01 80 42 00 00 00 00 00 00 00 00 00 00 00 4B 8B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 4C 08 01 80 42 00 00 00 00 00 00 00 00 00 00 00 4D 56 01 80 42 00 00 00 00 00 00 00 00 00 00 00 4E B4 01 80 42 00 00 00 00 00 00 00 00 00 00 00 4F EA 01 80 42 00 00 00 00 00 00 00 00 00 00 00 50 36 01 80 42 00 00 00 00 00 00 00 00 00 00 00 51 68 01 80 42 00 00 00 00 00 00 00 00 00 00 00 52 8A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 53 D4 01 80 42 00 00 00 00 00 00 00 00 00 00 00 54 57 01 80 42 00 00 00 00 00 00 00 00 00 00 00 55 09 01 80 42 00 00 00 00 00 00 00 00 00 00 00 56 EB 01 80 42 00 00 00 00 00 00 00 00 00 00 00 57 B5 01 80 42 00 00 00 00 00 00 00 00 00 00 00 58 F4 01 80 42 00 00 00 00 00 00 00 00 00 00 00 59 AA 01 80 42 00 00 00 00 00 00 00 00 00 00 00 5A 48 01 80 42 00 00 00 00 00 00 00 00 00 00 00 5B 16 01 80 42 00 00 00 00 00 00 00 00 00 00 00 5C 95 01 80 42 00 00 00 00 00 00 00 00 00 00 00 5D CB 01 80 42 00 00 00 00 00 00 00 00 00 00 00 5E 29 01 80 42 00 00 00 00 00 00 00 00 00 00 00 5F 77 01 80 42 00 00 00 00 00 00 00 00 00 00 00 60 88 01 80 42 00 00 00 00 00 00 00 00 00 00 00 61 D6 01 80 42 00 00 00 00 00 00 00 00 00 00 00 62 34 01 80 42 00 00 00 00 00 00 00 00 00 00 00 63 6A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 64 E9 01 80 42 00 00 00 00 00 00 00 00 00 00 00 65 B7 01 80 42 00 00 00 00 00 00 00 00 00 00 00 66 55 01 80 42 00 00 00 00 00 00 00 00 00 00 00 67 0B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 68 4A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 69 14 01 80 42 00 00 00 00 00 00 00 00 00 00 00 6A F6 01 80 42 00 00 00 00 00 00 00 00 00 00 00 6B A8 01 80 42 00 00 00 00 00 00 00 00 00 00 00 6C 2B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 6D 75 01 80 42 00 00 00 00 00 00 00 00 00 00 00 6E 97 01 80 42 00 00 00 00 00 00 00 00 00 00 00 6F C9 01 80 42 00 00 00 00 00 00 00 00 00 00 00 70 15 01 80 42 00 00 00 00 00 00 00 00 00 00 00 71 4B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 72 A9 01 80 42 00 00 00 00 00 00 00 00 00 00 00 73 F7 01 80 42 00 00 00 00 00 00 00 00 00 00 00 74 74 01 80 42 00 00 00 00 00 00 00 00 00 00 00 75 2A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 76 C8 01 80 42 00 00 00 00 00 00 00 00 00 00 00 77 96 01 80 42 00 00 00 00 00 00 00 00 00 00 00 78 D7 01 80 42 00 00 00 00 00 00 00 00 00 00 00 79 89 01 80 42 00 00 00 00 00 00 00 00 00 00 00 7A 6B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 7B 35 01 80 42 00 00 00 00 00 00 00 00 00 00 00 7C B6 01 80 42 00 00 00 00 00 00 00 00 00 00 00 7D E8 01 80 42 00 00 00 00 00 00 00 00 00 00 00 7E 0A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 7F 54 01 80 42 00 00 00 00 00 00 00 00 00 00 00 80 61 01 80 42 00 00 00 00 00 00 00 00 00 00 00 81 3F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 82 DD 01 80 42 00 00 00 00 00 00 00 00 00 00 00 83 83 01 80 42 00 00 00 00 00 00 00 00 00 00 00 84 00 01 80 42 00 00 00 00 00 00 00 00 00 00 00 85 5E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 86 BC 01 80 42 00 00 00 00 00 00 00 00 00 00 00 87 E2 01 80 42 00 00 00 00 00 00 00 00 00 00 00 88 A3 01 80 42 00 00 00 00 00 00 00 00 00 00 00 89 FD 01 80 42 00 00 00 00 00 00 00 00 00 00 00 8A 1F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 8B 41 01 80 42 00 00 00 00 00 00 00 00 00 00 00 8C C2 01 80 42 00 00 00 00 00 00 00 00 00 00 00 8D 9C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 8E 7E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 8F 20 01 80 42 00 00 00 00 00 00 00 00 00 00 00 90 FC 01 80 42 00 00 00 00 00 00 00 00 00 00 00 91 A2 01 80 42 00 00 00 00 00 00 00 00 00 00 00 92 40 01 80 42 00 00 00 00 00 00 00 00 00 00 00 93 1E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 94 9D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 95 C3 01 80 42 00 00 00 00 00 00 00 00 00 00 00 96 21 01 80 42 00 00 00 00 00 00 00 00 00 00 00 97 7F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 98 3E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 99 60 01 80 42 00 00 00 00 00 00 00 00 00 00 00 9A 82 01 80 42 00 00 00 00 00 00 00 00 00 00 00 9B DC 01 80 42 00 00 00 00 00 00 00 00 00 00 00 9C 5F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 9D 01 01 80 42 00 00 00 00 00 00 00 00 00 00 00 9E E3 01 80 42 00 00 00 00 00 00 00 00 00 00 00 9F BD 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A0 42 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A1 1C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A2 FE 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A3 A0 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A4 23 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A5 7D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A6 9F 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A7 C1 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A8 80 01 80 42 00 00 00 00 00 00 00 00 00 00 00 A9 DE 01 80 42 00 00 00 00 00 00 00 00 00 00 00 AA 3C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 AB 62 01 80 42 00 00 00 00 00 00 00 00 00 00 00 AC E1 01 80 42 00 00 00 00 00 00 00 00 00 00 00 AD BF 01 80 42 00 00 00 00 00 00 00 00 00 00 00 AE 5D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 AF 03 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B0 DF 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B1 81 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B2 63 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B3 3D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B4 BE 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B5 E0 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B6 02 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B7 5C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B8 1D 01 80 42 00 00 00 00 00 00 00 00 00 00 00 B9 43 01 80 42 00 00 00 00 00 00 00 00 00 00 00 BA A1 01 80 42 00 00 00 00 00 00 00 00 00 00 00 BB FF 01 80 42 00 00 00 00 00 00 00 00 00 00 00 BC 7C 01 80 42 00 00 00 00 00 00 00 00 00 00 00 BD 22 01 80 42 00 00 00 00 00 00 00 00 00 00 00 BE C0 01 80 42 00 00 00 00 00 00 00 00 00 00 00 BF 9E 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C0 27 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C1 79 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C2 9B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C3 C5 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C4 46 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C5 18 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C6 FA 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C7 A4 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C8 E5 01 80 42 00 00 00 00 00 00 00 00 00 00 00 C9 BB 01 80 42 00 00 00 00 00 00 00 00 00 00 00 CA 59 01 80 42 00 00 00 00 00 00 00 00 00 00 00 CB 07 01 80 42 00 00 00 00 00 00 00 00 00 00 00 CC 84 01 80 42 00 00 00 00 00 00 00 00 00 00 00 CD DA 01 80 42 00 00 00 00 00 00 00 00 00 00 00 CE 38 01 80 42 00 00 00 00 00 00 00 00 00 00 00 CF 66 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D0 BA 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D1 E4 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D2 06 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D3 58 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D4 DB 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D5 85 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D6 67 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D7 39 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D8 78 01 80 42 00 00 00 00 00 00 00 00 00 00 00 D9 26 01 80 42 00 00 00 00 00 00 00 00 00 00 00 DA C4 01 80 42 00 00 00 00 00 00 00 00 00 00 00 DB 9A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 DC 19 01 80 42 00 00 00 00 00 00 00 00 00 00 00 DD 47 01 80 42 00 00 00 00 00 00 00 00 00 00 00 DE A5 01 80 42 00 00 00 00 00 00 00 00 00 00 00 DF FB 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E0 04 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E1 5A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E2 B8 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E3 E6 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E4 65 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E5 3B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E6 D9 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E7 87 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E8 C6 01 80 42 00 00 00 00 00 00 00 00 00 00 00 E9 98 01 80 42 00 00 00 00 00 00 00 00 00 00 00 EA 7A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 EB 24 01 80 42 00 00 00 00 00 00 00 00 00 00 00 EC A7 01 80 42 00 00 00 00 00 00 00 00 00 00 00 ED F9 01 80 42 00 00 00 00 00 00 00 00 00 00 00 EE 1B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 EF 45 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F0 99 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F1 C7 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F2 25 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F3 7B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F4 F8 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F5 A6 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F6 44 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F7 1A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F8 5B 01 80 42 00 00 00 00 00 00 00 00 00 00 00 F9 05 01 80 42 00 00 00 00 00 00 00 00 00 00 00 FA E7 01 80 42 00 00 00 00 00 00 00 00 00 00 00 FB B9 01 80 42 00 00 00 00 00 00 00 00 00 00 00 FC 3A 01 80 42 00 00 00 00 00 00 00 00 00 00 00 FD 64 01 80 42 00 00 00 00 00 00 00 00 00 00 00 FE 86 01 80 42 00 00 00 00 00 00 00 00 00 00 00 FF D8 The second to last byte seems to be a sequential number that starts over at 00 when it reaches FF. I have included the whole range from 00 to FF to make it easier to guess the crc/checksum method.

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• Help finding longest non-repeating path through connected nodes - Python

  - by Jordan Magnuson

  I've been working on this for a couple of days now without success. Basically, I have a bunch of nodes arranged in a 2D matrix. Every node has four neighbors, except for the nodes on the sides and corners of the matrix, which have 3 and 2 neighbors, respectively. Imagine a bunch of square cards laid out side by side in a rectangular area--the project is actually simulating a sort of card/board game. Each node may or may not be connected to the nodes around it. Each node has a function (get_connections()), that returns the nodes immediately around it that it is connected to (so anywhere from 0 to 4 nodes are returned). Each node also has an "index" property, that contains it's position on the board matrix (eg '1, 4' - row 1, col 4). What I am trying to do is find the longest non-repeating path of connected nodes given a particular "start" node. I've uploaded a couple of images that should give a good idea of what I'm trying to do: In both images, the highlighted red cards are supposedly the longest path of connected cards containing the most upper-left card. However, you can see in both images that a couple of cards that should be in the path have been left out (Romania and Maldova in the first image, Greece and Turkey in the second) Here's the recursive function that I am using currently to find the longest path, given a starting node/card: def get_longest_trip(self, board, processed_connections = list(), processed_countries = list()): #Append this country to the processed countries list, #so we don't re-double over it processed_countries.append(self) possible_trips = dict() if self.get_connections(board): for i, card in enumerate(self.get_connections(board)): if card not in processed_countries: processed_connections.append((self, card)) possible_trips[i] = card.get_longest_trip(board, processed_connections, processed_countries) if possible_trips: longest_trip = [] for i, trip in possible_trips.iteritems(): trip_length = len(trip) if trip_length > len(longest_trip): longest_trip = trip longest_trip.append(self) return longest_trip else: print card_list = [] card_list.append(self) return card_list else: #If no connections from start_card, just return the start card #as the longest trip card_list = [] card_list.append(board.start_card) return card_list The problem here has to do with the processed_countries list: if you look at my first screenshot, you can see that what has happened is that when Ukraine came around, it looked at its two possible choices for longest path (Maldova-Romania, or Turkey, Bulgaria), saw that they were both equal, and chose one indiscriminantly. Now when Hungary comes around, it can't attempt to make a path through Romania (where the longest path would actually be), because Romania has been added to the processed_countries list by Ukraine. Any help on this is EXTREMELY appreciated. If you can find me a solution to this, recursive or not, I'd be happy to donate some $$ to you. I've uploaded my full source code (Python 2.6, Pygame 1.9 required) to: http://www.necessarygames.com/junk/planes_trains.zip The relevant code is in src/main.py, which is all set to run.

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• Fixed point math in c#?

  - by x4000

  Hi there, I was wondering if anyone here knows of any good resources for fixed point math in c#? I've seen things like this (http://2ddev.72dpiarmy.com/viewtopic.php?id=156) and this (http://stackoverflow.com/questions/79677/whats-the-best-way-to-do-fixed-point-math), and a number of discussions about whether decimal is really fixed point or actually floating point (update: responders have confirmed that it's definitely floating point), but I haven't seen a solid C# library for things like calculating cosine and sine. My needs are simple -- I need the basic operators, plus cosine, sine, arctan2, PI... I think that's about it. Maybe sqrt. I'm programming a 2D RTS game, which I have largely working, but the unit movement when using floating-point math (doubles) has very small inaccuracies over time (10-30 minutes) across multiple machines, leading to desyncs. This is presently only between a 32 bit OS and a 64 bit OS, all the 32 bit machines seem to stay in sync without issue, which is what makes me think this is a floating point issue. I was aware from this as a possible issue from the outset, and so have limited my use of non-integer position math as much as possible, but for smooth diagonal movement at varying speeds I'm calculating the angle between points in radians, then getting the x and y components of movement with sin and cos. That's the main issue. I'm also doing some calculations for line segment intersections, line-circle intersections, circle-rect intersections, etc, that also probably need to move from floating-point to fixed-point to avoid cross-machine issues. If there's something open source in Java or VB or another comparable language, I could probably convert the code for my uses. The main priority for me is accuracy, although I'd like as little speed loss over present performance as possible. This whole fixed point math thing is very new to me, and I'm surprised by how little practical information on it there is on google -- most stuff seems to be either theory or dense C++ header files. Anything you could do to point me in the right direction is much appreciated; if I can get this working, I plan to open-source the math functions I put together so that there will be a resource for other C# programmers out there. UPDATE: I could definitely make a cosine/sine lookup table work for my purposes, but I don't think that would work for arctan2, since I'd need to generate a table with about 64,000x64,000 entries (yikes). If you know any programmatic explanations of efficient ways to calculate things like arctan2, that would be awesome. My math background is all right, but the advanced formulas and traditional math notation are very difficult for me to translate into code.

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• Most efficient method to query a Young Tableau

  - by Matthieu M.

  A Young Tableau is a 2D matrix A of dimensions M*N such that: i,j in [0,M)x[0,N): for each p in (i,M), A[i,j] <= A[p,j] for each q in (j,N), A[i,j] <= A[i,q] That is, it's sorted row-wise and column-wise. Since it may contain less than M*N numbers, the bottom-right values might be represented either as missing or using (in algorithm theory) infinity to denote their absence. Now the (elementary) question: how to check if a given number is contained in the Young Tableau ? Well, it's trivial to produce an algorithm in O(M*N) time of course, but what's interesting is that it is very easy to provide an algorithm in O(M+N) time: Bottom-Left search: Let x be the number we look for, initialize i,j as M-1, 0 (bottom left corner) If x == A[i,j], return true If x < A[i,j], then if i is 0, return false else decrement i and go to 2. Else, if j is N-1, return false else increment j This algorithm does not make more than M+N moves. The correctness is left as an exercise. It is possible though to obtain a better asymptotic runtime. Pivot Search: Let x be the number we look for, initialize i,j as floor(M/2), floor(N/2) If x == A[i,j], return true If x < A[i,j], search (recursively) in A[0:i-1, 0:j-1], A[i:M-1, 0:j-1] and A[0:i-1, j:N-1] Else search (recursively) in A[i+1:M-1, 0:j], A[i+1:M-1, j+1:N-1] and A[0:i, j+1:N-1] This algorithm proceed by discarding one of the 4 quadrants at each iteration and running recursively on the 3 left (divide and conquer), the master theorem yields a complexity of O((N+M)**(log 3 / log 4)) which is better asymptotically. However, this is only a big-O estimation... So, here are the questions: Do you know (or can think of) an algorithm with a better asymptotical runtime ? Like introsort prove, sometimes it's worth switching algorithms depending on the input size or input topology... do you think it would be possible here ? For 2., I am notably thinking that for small size inputs, the bottom-left search should be faster because of its O(1) space requirement / lower constant term.

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• HLSL tex2d sampler seemingly returning incorrect values; why?

  - by BlueNovember

  Hello all, I have code that needs to render regions of my object differently depending on their location. I am trying to use a colour map to define these regions, then get a value (0-14) representing this region by sampling the texture. The problem is when I sample from my colour map, I get collisions. Ie, two regions with different colours in the colourmap get the same value returned from the sampler. I've tried various formats of my colour map. I set the colours for each region to be "5" apart in each case; Indexed colour RGB, RGBA: region 1 will have RGB 5,5,5. region 2 will have RGB 10,10,10 and so on. HSV Greyscale: region 1 will have HSV 0,0,5. region 2 will have HSV 0,0,10 and so on. The tex2D sampler returns a value [0..1]. To get the "region number" I multiply this by 100 and divide by 5, expecting a number [0..20]. (But currently only using 0-14) I am using Shader Model 2 and FX Composer. //Colour map texture gColourmapTexture < string ResourceName = "Globe_Colourmap_Regions_Greyscale.png"; string ResourceType = "2D"; >; sampler2D gColourmapSampler : register(s1) = sampler_state { Texture = <gColourmapTexture>; #if DIRECT3D_VERSION >= 0xa00 Filter = MIN_MAG_MIP_LINEAR; #else /* DIRECT3D_VERSION < 0xa00 */ MinFilter = Linear; MipFilter = Linear; MagFilter = Linear; #endif /* DIRECT3D_VERSION */ AddressU = Clamp; AddressV = Clamp; }; ... //Then later, in a method float region = tex2D(gColourmapSampler,In.UV).x; //at this point I do not think it matters which of xyz components I pick; even in HSV they're all the same for my image. region *= 100; //Now in range [0..100] region /= 5; //Now in range [0..20] float3 levels[21]; //*Code populating "levels" array with what is essentially colour information * levels[1] = ... levels[2] = ... //Chose which level this region has, by looking up its region number float3 Level = levels[region];

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• Tools to help with analysing log files

  - by peter

  I am developing a C# .NET application. In the app.config file I add trace logging as shown, <?xml version="1.0" encoding="UTF-8" ?> <configuration> <system.diagnostics> <trace autoflush="true" /> <sources> <source name="System.Net.Sockets" maxdatasize="1024"> <listeners> <add name="MyTraceFile"/> </listeners> </source> </sources> <sharedListeners> <add name="MyTraceFile" type="System.Diagnostics.TextWriterTraceListener" initializeData="System.Net.trace.log" /> </sharedListeners> <switches> <add name="System.Net" value="Verbose" /> </switches> </system.diagnostics> </configuration> Are there any good tools around to analyse the log file that is output? The output looks like this, System.Net.Sockets Verbose: 0 : [5900] Data from Socket#8764489::Send DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000000 : 4D 49 4D 45 2D 56 65 72-73 69 6F 6E 3A 20 31 2E : MIME-Version: 1. DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000060 : 65 3A 20 37 20 41 70 72-20 32 30 31 30 20 31 35 : e: 7 Apr 2010 15 DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000070 : 3A 32 32 3A 34 30 20 2B-31 32 30 30 0D 0A 53 75 : :22:40 +1200..Su DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000080 : 62 6A 65 63 74 3A 20 5B-45 72 72 6F 72 5D 20 45 : bject: [Error] E DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000090 : 78 63 65 70 74 69 6F 6E-20 69 6E 20 53 79 6E 63 : xception in Sync DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 000000A0 : 53 65 72 76 69 63 65 20-28 32 30 30 38 2E 30 2E : Service (2008.0. DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 000000B0 : 33 30 34 2E 31 32 33 34-32 29 0D 0A 43 6F 6E 74 : 304.12342)..Cont DateTime=2010-04-07T03:22:40.1067012Z Is there anything that can take the output shown above (my output is a text file 100mb in size), group together packets, and help out with finding particular issues I would like to hear about it. Thanks.

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• bug/error in basis set path algorithm i can't figure out

  - by Roy McAvoy

  The following looks through a 2d array to find basis set paths. It is supposed to print out the individual paths but not repeat any and end when all paths are found. It however doesn't stop at the last path and has a bug in it somewhere in which the following happens: It goes halfway through the path and then goes to zero and ends the path for some reason. For example the table is filled with the following: all 0s, except for [1][2], [1][3], [2][4], [2][5], [3][5], [4][6], [5][6], [6][0] which all have a 1 in them. The desired paths are P1: 1 2 4 6 0 P2: 1 3 5 6 0 P3: 1 2 5 6 0. The output I get when i run the program is 12460 13560 1250 124 Any and all help on this is much appreciated, this is just the function that scans through the array looking for paths, I can add the entire program if that would be helpful. Thanks.. void find_path(int map[][MAX], int x){ int path =0; int m=1; int blah=0; bool path_found = false; do { for(int n=0;n<(x+1);n++){ if(map[m][n]==-1){ blah=(n+1); if(blah<(x+1)){ for(blah;blah<(x+1);blah++){ if(map[m][blah]==1){ map[m][blah]=-1; path=m; path_found = true; cout<<path; m=blah; n=0; } } } else{ path=m; path_found=false; cout<<path; m=n; if(m==0){ path=0; cout<<path<<endl; m=1; path_found=false; } } } else if(map[m][n]==1){ map[m][n]=-1; path=m; path_found = true; cout<<path; m=n; if(m==0){ path=0; cout<<path<<endl; m=1; path_found=false; } } } } while(m<(x+1) && path_found); }

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• For loop from assembly to C

  - by FranXh

  I have a bomb project where I need to defuse certain phases by finding "pas phrases" that will defuse the bomb. Right now I have been working with phase_2, for which the assembly code is shown below. Phase_2 requires as an input 6 numbers, which I need to find in order to defuse this phase. I analyzed this assembly, and I came up with the C code below, that covers lines from 40101c to 401044. It is basically a for loop that makes sure that elements t[0]==t[3], t[1]==t[4] and t[2]==t[5] that the user inputs, are equal. According to my logic, the user can input any 6 numbers as long as the above condition is satisfied. Say 1, 2, 3, 1, 2, 3 would be a valid "pas phrase". However this solution does not convince me for some reason. Am I doing something wrong? 0000000000400ffc <phase_2>: 400ffc: 48 89 5c 24 e0 mov %rbx,-0x20(%rsp) 401001: 48 89 6c 24 e8 mov %rbp,-0x18(%rsp) 401006: 4c 89 64 24 f0 mov %r12,-0x10(%rsp) 40100b: 4c 89 6c 24 f8 mov %r13,-0x8(%rsp) 401010: 48 83 ec 48 sub $0x48,%rsp 401014: 48 89 e6 mov %rsp,%rsi 401017: e8 65 0a 00 00 callq 401a81 <read_six_numbers> 40101c: 48 89 e5 mov %rsp,%rbp 40101f: 4c 8d 6c 24 0c lea 0xc(%rsp),%r13 401024: 41 bc 00 00 00 00 mov $0x0,%r12d 40102a: 48 89 eb mov %rbp,%rbx 40102d: 8b 45 0c mov 0xc(%rbp),%eax 401030: 39 45 00 cmp %eax,0x0(%rbp) 401033: 74 05 je 40103a <phase_2+0x3e> 401035: e8 2d 09 00 00 callq 401967 <_GLOBAL_RESET_> 40103a: 44 03 23 add (%rbx),%r12d 40103d: 48 83 c5 04 add $0x4,%rbp 401041: 4c 39 ed cmp %r13,%rbp 401044: 75 e4 jne 40102a <phase_2+0x2e> 401046: 45 85 e4 test %r12d,%r12d 401049: 75 05 jne 401050 <phase_2+0x54> 40104b: e8 17 09 00 00 callq 401967 <_GLOBAL_RESET_> 401050: 48 8b 5c 24 28 mov 0x28(%rsp),%rbx 401055: 48 8b 6c 24 30 mov 0x30(%rsp),%rbp 40105a: 4c 8b 64 24 38 mov 0x38(%rsp),%r12 40105f: 4c 8b 6c 24 40 mov 0x40(%rsp),%r13 401064: 48 83 c4 48 add $0x48,%rsp 401068: c3 for (int i=0; i<3; i++){ if(t[i] != t[i+3]){ explode(); } }

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• wrong operator() overload called

  - by user313202

  okay, I am writing a matrix class and have overloaded the function call operator twice. The core of the matrix is a 2D double array. I am using the MinGW GCC compiler called from a windows console. the first overload is meant to return a double from the array (for viewing an element). the second overload is meant to return a reference to a location in the array (for changing the data in that location. double operator()(int row, int col) const ; //allows view of element double &operator()(int row, int col); //allows assignment of element I am writing a testing routine and have discovered that the "viewing" overload never gets called. for some reason the compiler "defaults" to calling the overload that returns a reference when the following printf() statement is used. fprintf(outp, "%6.2f\t", testMatD(i,j)); I understand that I'm insulting the gods by writing my own matrix class without using vectors and testing with C I/O functions. I will be punished thoroughly in the afterlife, no need to do it here. Ultimately I'd like to know what is going on here and how to fix it. I'd prefer to use the cleaner looking operator overloads rather than member functions. Any ideas? -Cal the matrix class: irrelevant code omitted class Matrix { public: double getElement(int row, int col)const; //returns the element at row,col //operator overloads double operator()(int row, int col) const ; //allows view of element double &operator()(int row, int col); //allows assignment of element private: //data members double **array; //pointer to data array }; double Matrix::getElement(int row, int col)const{ //transform indices into true coordinates (from sorted coordinates //only row needs to be transformed (user can only sort by row) row = sortedArray[row]; result = array[usrZeroRow+row][usrZeroCol+col]; return result; } //operator overloads double Matrix::operator()(int row, int col) const { //this overload is used when viewing an element return getElement(row,col); } double &Matrix::operator()(int row, int col){ //this overload is used when placing an element return array[row+usrZeroRow][col+usrZeroCol]; } The testing program: irrelevant code omitted int main(void){ FILE *outp; outp = fopen("test_output.txt", "w+"); Matrix testMatD(5,7); //construct 5x7 matrix //some initializations omitted fprintf(outp, "%6.2f\t", testMatD(i,j)); //calls the wrong overload }

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• What are the basics of dealing with user input events in Android?

  - by user279112

  Hello. I thought I had understood this question, but something is quite wrong here. When the user (me, so far) tries to press keys, nothing really happens, and I am having a lot of trouble understanding what it is that I've missed. Consider this before I present some code to help clarify my problem: I am using Android's Lunar Lander example to make my first "real" Android program. In that example, of course, there exist a class LunarView, and class nested therein LunarThread. In my code the equivalents of these classes are Graphics and GraphicsThread, respectively. Also I can make sprite animations in 2D just fine on Android. I have a Player class, and let's say GraphicsThread has a Player member referred to as "player". This class has four coordinates - x1, y1, x2, and y2 - and they define a rectangle in which the sprite is to be drawn. I've worked it out so that I can handle that perfectly. Whenever the doDraw(Canvas canvas) method is invoked, it'll just look at the values of those coordinates and draw the sprite accordingly. Now let's say - and this isn't really what I'm trying to do with the program - I'm trying to make the program where all it does is display the Player sprite at one location of the screen UNTIL the FIRST time the user presses the Dpad's left button. Then the location will be changed to another set position on the screen, and the sprite will be drawn at that position for the rest of the program invariably. Also note that the GraphicsThread member in Graphics is called "thread", and that the SurfaceHolder member in GraphicsThread is called "mSurfaceHolder". So consider this method in class Graphics: @Override public boolean onKeyDown(int keyCode, KeyEvent msg) { return thread.keyDownHandler(keyCode, msg); } Also please consider this method in class GraphicsThread: boolean keyDownHandler(int keyCode, KeyEvent msg) { synchronized (mSurfaceHolder) { if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) { player.x1 = 100; player.y1 = 100; player.x2 = 120; player.y2 = 150; } } return true; } Now then assuming that player's coordinates start off as (200, 200, 220, 250), why won't he do anything different when I press Dpad: Left? Thanks!

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• GCC: Simple inheritance test fails

  - by knight666

  I'm building an open source 2D game engine called YoghurtGum. Right now I'm working on the Android port, using the NDK provided by Google. I was going mad because of the errors I was getting in my application, so I made a simple test program: class Base { public: Base() { } virtual ~Base() { } }; // class Base class Vehicle : virtual public Base { public: Vehicle() : Base() { } ~Vehicle() { } }; // class Vehicle class Car : public Vehicle { public: Car() : Base(), Vehicle() { } ~Car() { } }; // class Car int main(int a_Data, char** argv) { Car* stupid = new Car(); return 0; } Seems easy enough, right? Here's how I compile it, which is the same way I compile the rest of my code: /home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin/arm-eabi-g++ -g -std=c99 -Wall -Werror -O2 -w -shared -fshort-enums -I ../../YoghurtGum/src/GLES -I ../../YoghurtGum/src -I /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/include -c src/Inheritance.cpp -o intermediate/Inheritance.o (Line breaks are added for clarity). This compiles fine. But then we get to the linker: /home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/bin/arm-eabi-gcc -lstdc++ -Wl, --entry=main, -rpath-link=/system/lib, -rpath-link=/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib, -dynamic-linker=/system/bin/linker, -L/home/oem/android-ndk-r3/build/prebuilt/linux-x86/arm-eabi-4.4.0/lib/gcc/arm-eabi/4.4.0, -L/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib, -rpath=../../YoghurtGum/lib/GLES -nostdlib -lm -lc -lGLESv1_CM -z /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib/crtbegin_dynamic.o /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib/crtend_android.o intermediate/Inheritance.o ../../YoghurtGum/bin/YoghurtGum.a -o bin/Galaxians.android As you can probably tell, there's a lot of cruft in there that isn't really needed. That's because it doesn't work. It fails with the following errors: intermediate/Inheritance.o:(.rodata._ZTI3Car[typeinfo for Car]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Inheritance.o:(.rodata._ZTI7Vehicle[typeinfo for Vehicle]+0x0): undefined reference to `vtable for __cxxabiv1::__vmi_class_type_info' intermediate/Inheritance.o:(.rodata._ZTI4Base[typeinfo for Base]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' collect2: ld returned 1 exit status make: *** [bin/Galaxians.android] Fout 1 These are the same errors I get from my actual application. If someone could explain to me where I went wrong in my test or what option or I forgot in my linker, I would be very, extremely grateful. Thanks in advance. UPDATE: When I make my destructors non-inlined, I get new and more exciting link errors: intermediate/Inheritance.o:(.rodata+0x78): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Inheritance.o:(.rodata+0x90): undefined reference to `vtable for __cxxabiv1::__vmi_class_type_info' intermediate/Inheritance.o:(.rodata+0xb0): undefined reference to `vtable for __cxxabiv1::__class_type_info' collect2: ld returned 1 exit status make: *** [bin/Galaxians.android] Fout 1

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• Restoring multiple database backups in a transaction

  - by Raghu Dodda

  I wrote a stored procedure that restores as set of the database backups. It takes two parameters - a source directory and a restore directory. The procedure looks for all .bak files in the source directory (recursively) and restores all the databases. The stored procedure works as expected, but it has one issue - if I uncomment the try-catch statements, the procedure terminates with the following error: error_number = 3013 error_severity = 16 error_state = 1 error_message = DATABASE is terminating abnormally. The weird part is sometimes (it is not consistent) the restore is done even if the error occurs. The procedure: create proc usp_restore_databases ( @source_directory varchar(1000), @restore_directory varchar(1000) ) as begin declare @number_of_backup_files int -- begin transaction -- begin try -- step 0: Initial validation if(right(@source_directory, 1) <> '\') set @source_directory = @source_directory + '\' if(right(@restore_directory, 1) <> '\') set @restore_directory = @restore_directory + '\' -- step 1: Put all the backup files in the specified directory in a table -- declare @backup_files table ( file_path varchar(1000)) declare @dos_command varchar(1000) set @dos_command = 'dir ' + '"' + @source_directory + '*.bak" /s/b' /* DEBUG */ print @dos_command insert into @backup_files(file_path) exec xp_cmdshell @dos_command delete from @backup_files where file_path IS NULL select @number_of_backup_files = count(1) from @backup_files /* DEBUG */ select * from @backup_files /* DEBUG */ print @number_of_backup_files -- step 2: restore each backup file -- declare backup_file_cursor cursor for select file_path from @backup_files open backup_file_cursor declare @index int; set @index = 0 while(@index < @number_of_backup_files) begin declare @backup_file_path varchar(1000) fetch next from backup_file_cursor into @backup_file_path /* DEBUG */ print @backup_file_path -- step 2a: parse the full backup file name to get the DB file name. declare @db_name varchar(100) set @db_name = right(@backup_file_path, charindex('\', reverse(@backup_file_path)) -1) -- still has the .bak extension /* DEBUG */ print @db_name set @db_name = left(@db_name, charindex('.', @db_name) -1) /* DEBUG */ print @db_name set @db_name = lower(@db_name) /* DEBUG */ print @db_name -- step 2b: find out the logical names of the mdf and ldf files declare @mdf_logical_name varchar(100), @ldf_logical_name varchar(100) declare @backup_file_contents table ( LogicalName nvarchar(128), PhysicalName nvarchar(260), [Type] char(1), FileGroupName nvarchar(128), [Size] numeric(20,0), [MaxSize] numeric(20,0), FileID bigint, CreateLSN numeric(25,0), DropLSN numeric(25,0) NULL, UniqueID uniqueidentifier, ReadOnlyLSN numeric(25,0) NULL, ReadWriteLSN numeric(25,0) NULL, BackupSizeInBytes bigint, SourceBlockSize int, FileGroupID int, LogGroupGUID uniqueidentifier NULL, DifferentialBaseLSN numeric(25,0) NULL, DifferentialBaseGUID uniqueidentifier, IsReadOnly bit, IsPresent bit ) insert into @backup_file_contents exec ('restore filelistonly from disk=' + '''' + @backup_file_path + '''') select @mdf_logical_name = LogicalName from @backup_file_contents where [Type] = 'D' select @ldf_logical_name = LogicalName from @backup_file_contents where [Type] = 'L' /* DEBUG */ print @mdf_logical_name + ', ' + @ldf_logical_name -- step 2c: restore declare @mdf_file_name varchar(1000), @ldf_file_name varchar(1000) set @mdf_file_name = @restore_directory + @db_name + '.mdf' set @ldf_file_name = @restore_directory + @db_name + '.ldf' /* DEBUG */ print 'mdf_logical_name = ' + @mdf_logical_name + '|' + 'ldf_logical_name = ' + @ldf_logical_name + '|' + 'db_name = ' + @db_name + '|' + 'backup_file_path = ' + @backup_file_path + '|' + 'restore_directory = ' + @restore_directory + '|' + 'mdf_file_name = ' + @mdf_file_name + '|' + 'ldf_file_name = ' + @ldf_file_name restore database @db_name from disk = @backup_file_path with move @mdf_logical_name to @mdf_file_name, move @ldf_logical_name to @ldf_file_name -- step 2d: iterate set @index = @index + 1 end close backup_file_cursor deallocate backup_file_cursor -- end try -- begin catch -- print error_message() -- rollback transaction -- return -- end catch -- -- commit transaction end Does anybody have any ideas why this might be happening? Another question: is the transaction code useful ? i.e., if there are 2 databases to be restored, will SQL Server undo the restore of one database if the second restore fails?

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• How to find relation between change in latitudes at centre of map and top/bottom

  - by Imran

  Hi, Im having little trouble finding a relation between the movement at centre and edge of a circle, Im doing for panning world map,my map extent is 180,89:-180,-89, my map pans by adding change(dx,dY) to its extents and not its centre. Now a situation has arrrised where I have to move the map to a specific centre, to calculate the change in longitudes is very easy and simple, but its the change in lattitudes that has caused problem. It seems the change in centreY of map is more than the change at edge of the mapY, or simply if I have to move the map centre from 0long,0lat to 73long,33lat, for dX I simply get 73, but for dY apparently it looks 33 but if i add 33 to top of map that is 89 , it will be 122 which is incorrect since Latitudes are between 90 and -90 . It seems a case a projection of a circle on 2D plane where the edge of circle since is moving backward due to angle expereinces less change and the centre expereinces more change, now is there a relation between these two factors? I tried converting the difference between OriginY and destinationY into radians and then add to Top and Bottom of Map, but it did'nt really work for me. Please note that the map is project on a virtual canvas whose width starts from 256 and increases by 256*2^z , z=0 is default and whole world is visible at that extent of canvas code: public void moveMapTo(double destinationLongitude,double destinationLattitude) // moves map to the new centre { double dXLong=destinationLongitude-centreLongitude; double atanhsinO = atanh(Math.sin(destinationLattitude * Math.PI / 180.00)); double atanhsinD = atanh(Math.sin(centreLatitude * Math.PI / 180.00)); double atanhCentre = (atanhsinD + atanhsinO) / 2; double latitudeSpan =destinationLattitude - centreLatitude; double radianOfCentreLatitude = Math.atan(Math.sinh(atanhCentre)); double dXLat=latitudeSpan / Math.cos(radianOfCentreLatitude); dXLat*=getLattitudeSpan()*(Math.PI/180); <--- HERE IS THE PORBLEM System.out.println("dxLong:"+dXLong+"_dxLat:"+dXLat); mapLeft+=dXLong; mapRight+=dXLong; mapTop+=dXLat; mapBottom+=dXLat; } ////latitude span function private double getLattitudeSpan() { double latitudeSpan = mapTop - mapBottom; latitudeSpan = latitudeSpan / Math.cos(radianOfCentreLatitude); return Math.abs(latitudeSpan); } //ht

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• Extracting Certain XML Elements with PHP SimpleXML

  - by Peter

  I am having some problems parsing this piece of XML using SimpleXML. There is always only one Series element, and a variable number of Episode elements beneath. I want to parse XML so I can store the Series data in one table, and all the Episode data in another table. XML: <Data> <Series> <id>80348</id> <Genre>|Action and Adventure|Comedy|Drama|</Genre> <IMDB_ID>tt0934814</IMDB_ID> <SeriesID>68724</SeriesID> <SeriesName>Chuck</SeriesName> <banner>graphical/80348-g.jpg</banner> </Series> <Episode> <id>935481</id> <Director>Robert Duncan McNeill</Director> <EpisodeName>Chuck Versus the Third Dimension 2D</EpisodeName> <EpisodeNumber>1</EpisodeNumber> <seasonid>27984</seasonid> <seriesid>80348</seriesid> </Episode> <Episode> <id>935483</id> <Director>Robert Duncan McNeill</Director> <EpisodeName>Buy More #15: Employee Health</EpisodeName> <EpisodeNumber>2</EpisodeNumber> <seasonid>27984</seasonid> <seriesid>80348</seriesid> </Episode> </Data> When I attempt to access just the first Series element and child nodes, or iterate through the Episode elements only it does not work. I have also tried to use DOMDocument with SimpleXML, but could not get that to work at all. PHP Code: <?php if(file_exists('en.xml')) { $data = simplexml_load_file('en.xml'); foreach($data as $series) { echo 'id: <br />' . $series->id; echo 'imdb: <br />' . $series->IMDB_ID; } } ?> Output: id:80348 imdb:tt0934814 id:935481 imdb: id:1534641 imdb: Any help would be greatly appreciated.

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• Drawing text to <canvas> with @font-face does not work at the first time

  - by lemonedo

  Hi all, First try the test case please: http://lemon-factory.net/test/font-face-and-canvas.html I'm not good at English, so I made the test case to be self-explanatory. On the first click to the DRAW button, it will not draw text, or will draw with an incorrect typeface instead of the specified "PressStart", according to your browser. After then it works as expected. At the first time the text does not appear correctly in all browsers I've tested (Firefox, Google Chrome, Safari, Opera). Is it the standard behavior or something? Thank you. PS: Following is the code of the test case <!DOCTYPE html> <html> <head> <meta http-equiv=Content-Type content="text/html;charset=utf-8"> <title>@font-face and canvas</title> <style> @font-face { font-family: 'PressStart'; src: url('http://lemon-factory.net/css/fonts/prstart.ttf'); } canvas, pre { border: 1px solid #666; } pre { float: left; margin: .5em; padding: .5em; } </style> </head> <body> <div> <canvas id=canvas width=250 height=250> Your browser does not support the CANVAS element. Try the latest Firefox, Google Chrome, Safari or Opera. </canvas> <button>DRAW</button> </div> <pre id=style></pre> <pre id=script></pre> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script> <script> var canvas = document.getElementById('canvas') var ctx = canvas.getContext('2d') var x = 30 var y = 10 function draw() { ctx.font = '12px PressStart' ctx.fillStyle = '#000' ctx.fillText('Hello, world!', x, y += 20) ctx.fillRect(x - 20, y - 10, 10, 10) } $('button').click(draw) $('pre#style').text($('style').text()) $('pre#script').text($('script').text()) </script> </body> </html>

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• Help creating a JavaScript mixin in Tapestry5?

  - by shane87

  I am creating a mixin which renders a javascript file when a textfield gains focus. I am new to the idea of mixins in Tapestry, and I am unsure of where to place my original javascript file which i wish to run when the textfield gains focus. The following is an example of my code: The Java mixin class: package asc.mixins; import org.apache.tapestry5.RenderSupport; import org.apache.tapestry5.annotations.AfterRender; import org.apache.tapestry5.annotations.Environmental; import org.apache.tapestry5.annotations.IncludeJavaScriptLibrary; import org.apache.tapestry5.annotations.InjectContainer; import org.apache.tapestry5.corelib.base.AbstractTextField; @IncludeJavaScriptLibrary("js_dasher_mixin.js") public class DasherMixin { @Environmental private RenderSupport renderSupport; @InjectContainer private AbstractTextField field; @AfterRender void addScript() { this.renderSupport.addScript("new JSDasher('%s');", this.field.getClientId()); } } The Javascript mixin file: JSDasher = Class.create({ initialize: function(textField) { this.textField = $(textField); this.textField.observe('focus', this.onFocus.bindAsEventListener(this)); }, onFocus: function(event) { //call my javascript init() function } } part of my javascript file I wish to run when the textfield gains focus: var posX, posY; // Sets up our global variables and dispatches an init request to the server. function init() { posX=0; posY=0; canvas = document.getElementById("canvas"); canvasWidth = canvas.offsetWidth; canvasHeight = canvas.offsetHeight; if (canvas.getContext) { ctx = canvas.getContext("2d"); } canvas.onclick = canvasClicked; canvas.onmousemove = mouseMoved; canvasOffsetX = findPosX(canvas); canvasOffsetY = findPosY(canvas); sessID = -1; sendInitRQ(canvasWidth, canvasHeight); } My javascript file is much larger than above, my question is where should I put my javascript code above? Should it all be contained in the mixin.js file? if so where exactly should it go? Thanks in advance for any help.

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• Tools to Help out with

  - by peter

  I am developing a C# .NET application. In the app.config file I add trace logging as shown, <?xml version="1.0" encoding="UTF-8" ?> <configuration> <system.diagnostics> <trace autoflush="true" /> <sources> <source name="System.Net.Sockets" maxdatasize="1024"> <listeners> <add name="MyTraceFile"/> </listeners> </source> </sources> <sharedListeners> <add name="MyTraceFile" type="System.Diagnostics.TextWriterTraceListener" initializeData="System.Net.trace.log" /> </sharedListeners> <switches> <add name="System.Net" value="Verbose" /> </switches> </system.diagnostics> </configuration> Are there any good tools around to analyse the log file that is output? The output looks like this, System.Net.Sockets Verbose: 0 : [5900] Data from Socket#8764489::Send DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000000 : 4D 49 4D 45 2D 56 65 72-73 69 6F 6E 3A 20 31 2E : MIME-Version: 1. DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000060 : 65 3A 20 37 20 41 70 72-20 32 30 31 30 20 31 35 : e: 7 Apr 2010 15 DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000070 : 3A 32 32 3A 34 30 20 2B-31 32 30 30 0D 0A 53 75 : :22:40 +1200..Su DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000080 : 62 6A 65 63 74 3A 20 5B-45 72 72 6F 72 5D 20 45 : bject: [Error] E DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000090 : 78 63 65 70 74 69 6F 6E-20 69 6E 20 53 79 6E 63 : xception in Sync DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 000000A0 : 53 65 72 76 69 63 65 20-28 32 30 30 38 2E 30 2E : Service (2008.0. DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 000000B0 : 33 30 34 2E 31 32 33 34-32 29 0D 0A 43 6F 6E 74 : 304.12342)..Cont DateTime=2010-04-07T03:22:40.1067012Z Is there anything that can take the output shown above (my output is a text file 100mb in size), group together packets, and help out with finding particular issues I would like to hear about it. Thanks.

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• Flipping OpenGL texture

  - by Mk12

  When I load textures from images normally, they are upside down because of OpenGL's coordinate system. What would be the best way to flip them? glScalef(1.0f, -1.0f, 1.0f); vertically flipping the image files manually (in Photoshop) flipping them programatically after loading them (I don't know how) This is the method I'm using to load png textures, in my Utilities.m file (Objective-C): + (GLuint)loadPngTexture:(NSString *)name { CFURLRef textureURL = CFBundleCopyResourceURL( CFBundleGetMainBundle(), (CFStringRef)name, CFSTR("png"), CFSTR("Textures")); NSAssert(textureURL, @"Texture name invalid"); CGImageSourceRef imageSource = CGImageSourceCreateWithURL(textureURL, NULL); NSAssert(imageSource, @"Invalid Image Path."); NSAssert((CGImageSourceGetCount(imageSource) > 0), @"No Image in Image Source."); CFRelease(textureURL); CGImageRef image = CGImageSourceCreateImageAtIndex(imageSource, 0, NULL); NSAssert(image, @"Image not created."); CFRelease(imageSource); NSUInteger width = CGImageGetWidth(image); NSUInteger height = CGImageGetHeight(image); void *data = malloc(width * height * 4); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); NSAssert(colorSpace, @"Colorspace not created."); CGContextRef context = CGBitmapContextCreate( data, width, height, 8, width * 4, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Host); NSAssert(context, @"Context not created."); CGColorSpaceRelease(colorSpace); CGContextDrawImage(context, CGRectMake(0, 0, width, height), image); CGImageRelease(image); CGContextRelease(context); GLuint textureId; glGenTextures(1, &textureId); glBindTexture(GL_TEXTURE_2D, textureId); glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP_SGIS, GL_TRUE); glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_INT_8_8_8_8_REV, data); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE_SGIS); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE_SGIS); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR); free(data); return textureId; } Also, another thing I was wondering about: If I made a simple 2d game, with pixels mapped to units, would it be alright to set it up so that the origin is in the top-left corner, or would I run in to problems with other things (e.g. text rendering)? Thanks.

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• Anybody Know of any Tools to help Analysing .NET Trace Log Files?

  - by peter

  I am developing a C# .NET application. In the app.config file I add trace logging as shown, <?xml version="1.0" encoding="UTF-8" ?> <configuration> <system.diagnostics> <trace autoflush="true" /> <sources> <source name="System.Net.Sockets" maxdatasize="1024"> <listeners> <add name="MyTraceFile"/> </listeners> </source> </sources> <sharedListeners> <add name="MyTraceFile" type="System.Diagnostics.TextWriterTraceListener" initializeData="System.Net.trace.log" /> </sharedListeners> <switches> <add name="System.Net" value="Verbose" /> </switches> </system.diagnostics> </configuration> Are there any good tools around to analyse the log file that is output? The output looks like this, System.Net.Sockets Verbose: 0 : [5900] Data from Socket#8764489::Send DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000000 : 4D 49 4D 45 2D 56 65 72-73 69 6F 6E 3A 20 31 2E : MIME-Version: 1. DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000060 : 65 3A 20 37 20 41 70 72-20 32 30 31 30 20 31 35 : e: 7 Apr 2010 15 DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000070 : 3A 32 32 3A 34 30 20 2B-31 32 30 30 0D 0A 53 75 : :22:40 +1200..Su DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000080 : 62 6A 65 63 74 3A 20 5B-45 72 72 6F 72 5D 20 45 : bject: [Error] E DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 00000090 : 78 63 65 70 74 69 6F 6E-20 69 6E 20 53 79 6E 63 : xception in Sync DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 000000A0 : 53 65 72 76 69 63 65 20-28 32 30 30 38 2E 30 2E : Service (2008.0. DateTime=2010-04-07T03:22:40.1067012Z System.Net.Sockets Verbose: 0 : [5900] 000000B0 : 33 30 34 2E 31 32 33 34-32 29 0D 0A 43 6F 6E 74 : 304.12342)..Cont DateTime=2010-04-07T03:22:40.1067012Z Is there anything that can take the output shown above (my output is a text file 100mb in size), group together packets, and help out with finding particular issues I would like to hear about it. Thanks.

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• Simplifying a four-dimensional rule table in Matlab: addressing rows and columns of each dimension

  - by Cate

  Hi all. I'm currently trying to automatically generate a set of fuzzy rules for a set of observations which contain four values for each observation, where each observation will correspond to a state (a good example is with Fisher's Iris Data). In Matlab I am creating a four dimensional rule table where a single cell (a,b,c,d) will contain the corresponding state. To reduce the table I am following the Hong and Lee method of row and column similarity checking but I am having difficulty understanding how to address the third and fourth dimensions' rows and columns. From the method it is my understanding that each dimension is addressed individually and if the rule is true, the table is simplified. The rules for merging are as follows: If all cells in adjacent columns or rows are the same. If two cells are the same or if either of them is empty in adjacent columns or rows and at least one cell in both is not empty. If all cells in a column or row are empty and if cells in its two adjacent columns or rows are the same, merge the three. If all cells in a column or row are empty and if cells in its two adjacent columns or rows are the same or either of them is empty, merge the three. If all cells in a column or row are empty and if all the non-empty cells in the column or row to its left have the same region, and all the non-empty cells in the column or row to its right have the same region, but one different from the previously mentioned region, merge these three columns into two parts. Now for the confusing bit. Simply checking if the entire row/column is the same as the adjacent (rule 1) seems simple enough: if (a,:,:,:) == (a+1,:,:,:) (:,b,:,:) == (:,b+1,:,:) (:,:,c,:) == (:,:,c+1,:) (:,:,:,d) == (:,:,:,d+1) is this correct? but to check if the elements in the row/column match, or either is zero (rules 2 and 4), I am a bit lost. Would it be something along these lines: for a = 1:20 for i = 1:length(b) if (a+1,i,:,:) == (a,i,:,:) ... else if (a+1,i,:,:) == 0 ... else if (a,i,:,:) == 0 etc. and for the third and fourth dimensions: for c = 1:20 for i = 1:length(a) if (i,:,c,:) == (i,:,c+1,:) ... else if (i,:,c+1,:) == 0 ... else if (i,:,c,:) == 0 etc. for d = 1:20 for i = 1:length(a) if (i,:,:,d) == (i,:,:,d+1) ... else if (i,:,:,d+1) == 0 ... else if (i,:,:,d) == 0 etc. even any help with four dimensional arrays would be useful as I'm so confused by the thought of more than three! I would advise you look at the paper to understand my meaning - they themselves have used the Iris data but only given an example with a 2D table. Thanks in advance, hopefully!

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• HLSL tex2d sampler seemingly using inconsistent rounding; why?

  - by RJFalconer

  Hello all, I have code that needs to render regions of my object differently depending on their location. I am trying to use a colour map to define these regions. The problem is when I sample from my colour map, I get collisions. Ie, two regions with different colours in the colourmap get the same value returned from the sampler. I've tried various formats of my colour map. I set the colours for each region to be "5" apart in each case; Indexed colour RGB, RGBA: region 1 will have RGB 5%,5%,5%. region 2 will have RGB 10%,10%,10% and so on. HSV Greyscale: region 1 will have HSV 0,0,5%. region 2 will have HSV 0,0,10% and so on. (Values selected in The Gimp) The tex2D sampler returns a value [0..1]. [ I then intend to derive an int array index from region. Code to do with that is unrelated, so has been removed from the question ] float region = tex2D(gColourmapSampler,In.UV).x; Sampling the "5%" colour gave a "region" of 0.05098 in hlsl. From this I assume the 5% represents 5/100*255, or 12.75, which is rounded to 13 when stored in the texture OR when sampled by the sampler; can't tell which. (Reasoning: 0.05098 * 255 ~= 13) By this logic, the 50% should be stored as 127.5. Sampled, I get 0.50196 which implies it was stored as 128. the 70% should be stored as 178.5. Sampled, I get 0.698039, which implies it was stored as 178. What rounding is going on here? (127.5 becomes 128, 178.5 becomes 178 ?!) Edit: OK, http://en.wikipedia.org/wiki/Bankers_rounding#Round_half_to_even Apparently this is "banker's rounding". Is this really what HLSL samplers use? I am using Shader Model 2 and FX Composer. This is my sampler declaration; //Colour map texture gColourmapTexture < string ResourceName = "Globe_Colourmap_Regions_Greyscale.png"; string ResourceType = "2D"; >; sampler2D gColourmapSampler : register(s1) = sampler_state { Texture = <gColourmapTexture>; #if DIRECT3D_VERSION >= 0xa00 Filter = MIN_MAG_MIP_LINEAR; #else /* DIRECT3D_VERSION < 0xa00 */ MinFilter = Linear; MipFilter = Linear; MagFilter = Linear; #endif /* DIRECT3D_VERSION */ AddressU = Clamp; AddressV = Clamp; };

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• Javascript not getting keyDown input

  - by William

  For some reason my code just isn't wanting to fire off any kind of OnKeyDown event. I don't know why. Can anyone tell me what I'm doing wrong? <!DOCTYPE html> <html lang="en"> <head> <title>Canvas test</title> <meta charset="utf-8" /> <link href="/bms/style.css" rel="stylesheet" /> <style> body { text-align: center; background-color: #000000;} canvas{ background-color: #ffffff;} </style> <script type="text/javascript"> var x = 50; var y = 250; var speed = 5; function controls(event){ if(!e){ //for IE e = window.event; } if(e.keyCode==37){//keyCode 37 is left arrow x -= speed; } if(e.keyCode==39){ //keyCode 39 is right arrow x += speed; } if(e.keyCode==38){//keyCode 37 is up arrow y -= speed; } if(e.keyCode==40){ //keyCode 39 is down arrow y += speed; } } function update(){ document.onkeydown="controls(event);"; draw(); } function draw(){ var canvas = document.getElementById('screen1'); if (canvas.getContext){ var ctx = canvas.getContext('2d'); ctx.fillStyle = 'rgba(255,255,255,0.5)'; ctx.fillRect(0,0,500,500); ctx.fillStyle = 'rgb(236,138,68)'; ctx.fillRect(x,y,25,25); } } setInterval('update();', 1000/60); </script> </head> <body> <canvas id="screen1" width="500" height="500"></canvas> </body> </html>

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• Opinions on collision detection objects with a moving scene

  - by Evan Teran

  So my question is simple, and I guess it boils down to how anal you want to be about collision detection. To keep things simple, lets assume we're talking about 2D sprites defined by a bounding box. In addition, let's assume that my sprite object has a function to detect collisions like this: S.collidesWith(other); Finally the scene is moving and "walls" in the scene can move, an object may not touch a wall. So a simple implementation might look like this (psuedo code): moveWalls(); moveSprite(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } The problem with this is that if the sprite and wall move towards each other, depending on the circumstances (such as diagonal moment). They may pass though each other (unlikely but could happen). So I may do this instead. moveWalls(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } moveSprite(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } This takes care of the passing through each other issue, but another rare issue comes up. If they are adjacent to each other (literally the next pixel) and both the wall and the sprite are moving left, then I will get an invalid collision since the wall moves, checks for collision (hit) then the sprite is moved. Which seems unfair. In addition, to that, the redundant collision detection feels very inefficient. I could give the player movement priority alleviating the first issue but it is still checking twice. moveSprite(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } moveWalls(); foreach(wall as w) { if(s.collidesWith(w)) { gameover(); } } Am I simply over thinking this issue, should this just be chalked up to "it'll happen rare enough that no one will care"? Certainly looking at old sprite based games, I often find situations where the collision detection has subtle flaws, but I figure by now we can do better :-P. What are people's thoughts?

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• MATLAB image corner coordinates & referncing to cell arrays

  - by James

  Hi, I am having some problems comparing the elements in different cell arrays. The context of this problem is that I am using the bwboundaries function in MATLAB to trace the outline of an image. The image is of a structural cross section and I am trying to find if there is continuity throughout the section (i.e. there is only one outline produced by the bwboundaries command). Having done this and found where the is more than one section traced (i.e. it is not continuous), I have used the cornermetric command to find the corners of each section. The code I have is: %% Define the structural section as a binary matrix (Image is an I-section with the web broken) bw(20:40,50:150) = 1; bw(160:180,50:150) = 1; bw(20:60,95:105) = 1; bw(140:180,95:105) = 1; Trace = bw; [B] = bwboundaries(Trace,'noholes'); %Traces the outer boundary of each section L = length(B); % Finds number of boundaries if L > 1 disp('Multiple boundaries') % States whether more than one boundary found end %% Obtain perimeter coordinates for k=1:length(B) %For all the boundaries perim = B{k}; %Obtains perimeter coordinates (as a 2D matrix) from the cell array end %% Find the corner positions C = cornermetric(bw); Areacorners = find(C == max(max(C))) % Finds the corner coordinates of each boundary [rowindexcorners,colindexcorners] = ind2sub(size(Newgeometry),Areacorners) % Convert corner coordinate indexes into subcripts, to give x & y coordinates (i.e. the same format as B gives) %% Put these corner coordinates into a cell array Cornerscellarray = cell(length(rowindexcorners),1); % Initialises cell array of zeros for i =1:numel(rowindexcorners) Cornerscellarray(i) = {[rowindexcorners(i) colindexcorners(i)]}; %Assigns the corner indicies into the cell array %This is done so the cell arrays can be compared end for k=1:length(B) %For all the boundaries found perim = B{k}; %Obtains coordinates for each perimeter Z = perim; % Initialise the matrix containing the perimeter corners Sectioncellmatrix = cell(length(rowindexcorners),1); for i =1:length(perim) Sectioncellmatrix(i) = {[perim(i,1) perim(i,2)]}; end for i = 1:length(perim) if Sectioncellmatrix(i) ~= Cornerscellarray Sectioncellmatrix(i) = []; %Gets rid of the elements that are not corners, but keeps them associated with the relevent section end end end This creates an error in the last for loop. Is there a way I can check whether each cell of the array (containing an x and y coordinate) is equal to any pair of coordinates in cornercellarray? I know it is possible with matrices to compare whether a certain element matches any of the elements in another matrix. I want to be able to do the same here, but for the pair of coordinates within the cell array. The reason I don't just use the cornercellarray cell array itself, is because this lists all the corner coordinates and does not associate them with a specific traced boundary.

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• How do I stack images to simulate depth using Core Animation?

  - by Jeffrey Berthiaume

  I have a series of UIImages with which I need to simulate depth. I can't use scaling because I need to be able to rotate the parent view, and the images should look like they're stacked visibly in front of each other, not on the same plane. I made a new ViewController-based project and put this in the viewDidLoad (as well as attached three 120x120 pixel images named 1.png, 2.png, and 3.png): - (void)viewDidLoad { // display image 3 UIImageView *three = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"3.png"]]; three.center = CGPointMake(160 + 60, 240 - 60); [self.view addSubview:three]; // rotate image 3 around the z axis // THIS IS INCORRECT CATransform3D theTransform = three.layer.transform; theTransform.m34 = 1.0 / -1000; three.layer.transform = theTransform; // display image 2 UIImageView *two = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"2.png"]]; two.center = CGPointMake(160, 240); [self.view addSubview:two]; // display image 1 UIImageView *one = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"1.png"]]; one.center = CGPointMake(160 - 60, 240 + 60); [self.view addSubview:one]; // rotate image 3 around the z axis // THIS IS INCORRECT theTransform = one.layer.transform; theTransform.m34 = 1.0 / 1000; one.layer.transform = theTransform; // release the images [one release]; [two release]; [three release]; // rotate the parent view around the y axis theTransform = self.view.layer.transform; theTransform.m14 = 1.0 / -500; self.view.layer.transform = theTransform; [super viewDidLoad]; } I have very specific reasons why I'm not using an EAGLView and why I'm not loading the images as CALayers (i.e. why I'm using UIImageViews for each one). This is just a quick demo that I can use to work out exactly what I need in my parent application. Is there some matrix way to translate these 2d images along the z-axis so they will look like what I'm trying to represent? I've gone through the other StackOverflow articles as well as the Wikipedia references, and have not found what I'm looking for -- although I might not necessarily be using the right terms for what I'm trying to do.

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