1 // Copyright 2009 Google Inc. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 #pragma once 16 17 #define MAX_ETC_SUPPORTED 12 18 19 #define ETC1_ENCODED_BLOCK_SIZE 8 20 #define ETC1_DECODED_BLOCK_SIZE 48 21 #define ETC2_DECODED_RGB8A1_BLOCK_SIZE 64 22 #define EAC_ENCODE_ALPHA_BLOCK_SIZE 8 23 #define EAC_DECODED_ALPHA_BLOCK_SIZE 16 24 #define EAC_ENCODE_R11_BLOCK_SIZE 8 25 #define EAC_DECODED_R11_BLOCK_SIZE 64 26 #define EAC_DECODED_RG11_BLOCK_SIZE (EAC_DECODED_R11_BLOCK_SIZE*2) 27 28 #ifndef ETC1_RGB8_OES 29 #define ETC1_RGB8_OES 0x8D64 30 #endif 31 32 typedef unsigned char etc1_byte; 33 typedef int etc1_bool; 34 typedef unsigned int etc1_uint32; 35 36 enum ETC2ImageFormat { 37 EtcRGB8, EtcRGBA8, EtcR11, EtcSignedR11, EtcRG11, EtcSignedRG11, EtcRGB8A1 38 }; 39 40 #ifdef __cplusplus 41 extern "C" { 42 #endif 43 44 // Encode a block of pixels. 45 // 46 // pIn is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 47 // 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 48 // value of pixel (x, y). 49 // 50 // validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether 51 // the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing. 52 // 53 // pOut is an ETC1 compressed version of the data. 54 55 void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 validPixelMask, etc1_byte* pOut); 56 57 // Decode a block of rgb pixels. 58 // 59 // pIn is an ETC2 compressed version of the data. 60 // 61 // pOut is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a 62 // 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R 63 // value of pixel (x, y). 64 65 void etc2_decode_rgb_block(const etc1_byte* pIn, bool isPunchthroughAlpha, etc1_byte* pOut); 66 67 // Decode a block of single channel pixels 68 // This is used when decoding the alpha channel of RGBA8_ETC2_EAC format, or 69 // when decoding R11_EAC format 70 // decodedElementBytes: number of bits per element after decoding. 71 // For RGBA8_ETC2_EAC it must be 1, for R11_EAC it must be 2 72 73 void eac_decode_single_channel_block(const etc1_byte* pIn, 74 int decodedElementBytes, bool isSigned, 75 etc1_byte* pOut); 76 77 // Return the size of the encoded image data (does not include size of PKM header). 78 79 etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height); 80 81 etc1_uint32 etc_get_encoded_data_size(ETC2ImageFormat format, etc1_uint32 width, 82 etc1_uint32 height); 83 etc1_uint32 etc_get_decoded_pixel_size(ETC2ImageFormat format); 84 85 // Encode an entire image. 86 // pIn - pointer to the image data. Formatted such that 87 // pixel (x,y) is at pIn + pixelSize * x + stride * y; 88 // pOut - pointer to encoded data. Must be large enough to store entire encoded image. 89 // pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image. 90 // returns non-zero if there is an error. 91 92 int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height, 93 etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut); 94 95 // Decode an entire image. 96 // pIn - pointer to encoded data. 97 // pOut - pointer to the image data. Will be written such that 98 // pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be 99 // large enough to store entire image. 100 // (pixelSize=3 for rgb images, pixelSize=4 for images with alpha channel) 101 // returns non-zero if there is an error. 102 103 int etc2_decode_image(const etc1_byte* pIn, ETC2ImageFormat format, 104 etc1_byte* pOut, 105 etc1_uint32 width, etc1_uint32 height, 106 etc1_uint32 stride); 107 108 // Size of a PKM header, in bytes. 109 110 #define ETC_PKM_HEADER_SIZE 16 111 112 // Format a PKM header 113 114 void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height); 115 116 // Check if a PKM header is correctly formatted. 117 118 etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader); 119 120 // Read the image width from a PKM header 121 122 etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader); 123 124 // Read the image height from a PKM header 125 126 etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader); 127 128 #ifdef __cplusplus 129 } 130 #endif 131