198 lines
8.6 KiB
Markdown
198 lines
8.6 KiB
Markdown
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# Etc2Comp - Texture to ETC2 compressor
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Etc2Comp is a command line tool that converts textures (e.g. bitmaps)
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into the [ETC2](https://en.wikipedia.org/wiki/Ericsson_Texture_Compression)
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format. The tool is built with a focus on encoding performance
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to reduce the amount of time required to compile asset heavy applications as
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well as reduce overall application size.
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This repo provides source code that can be compiled into a binary. The
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binary can then be used to convert textures to the ETC2 format.
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Important: This is not an official Google product. It is an experimental
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library published as-is. Please see the CONTRIBUTORS.md file for information
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about questions or issues.
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## Setup
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This project uses [CMake](https://cmake.org/) to generate platform-specific
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build files:
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- Linux: make files
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- OS X: Xcode workspace files
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- Microsoft Windows: Visual Studio solution files
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- Note: CMake supports other formats, but this doc only provides steps for
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one of each platform for brevity.
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Refer to each platform's setup section to setup your environment and build
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an Etc2Comp binary. Then skip to the usage section of this page for examples
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of how to use the library.
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### Setup for OS X
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build tested on this config:
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OS X 10.9.5 i7 16GB RAM
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Xcode 5.1.1
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cmake 3.2.3
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Start by downloading and installing the following components if they are not
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already installed on your development machine.
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- *Xcode* version 5.1.1, or greater
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- [CMake](https://cmake.org/download/) version 3.2.3, or greater
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To build the Etc2Comp binary:
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1. Open a *Terminal* window and navigate to the project directory.
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1. Run `mkdir build_xcode`
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1. Run `cd build_xcode`
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1. Run `cmake -G Xcode ../`
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1. Open *Xcode* and import the `build_xcode/EtcTest.xcodeproj` file.
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1. Open the Product menu and choose Build For -> Running.
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1. Once the build succeeds the binary located at `build_xcode/EtcTool/Debug/EtcTool`
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can be executed.
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Optional
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Xcode EtcTool ‘Run’ preferences
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note: if the build_xcode/EtcTest.xcodeproj is manually deleted then some Xcode preferences
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will need to be set by hand after cmake is run (these prefs are retained across
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cmake updates if the .xcodeproj is not deleted/removed)
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1. Set the active scheme to ‘EtcTool’
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1. Edit the scheme
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1. Select option ‘Run EtcTool’, then tab ‘Arguments’.
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Add this launch argument: ‘-argfile ../../EtcTool/args.txt’
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1. Select tab ‘Options’ and set a custom working directory to: ‘$(SRCROOT)/Build_Xcode/EtcTool’
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### SetUp for Windows
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1. Open a *Terminal* window and navigate to the project directory.
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1. Run `mkdir build_vs`
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1. Run `cd build_vs`
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1. Run CMAKE, noting what build version you need, and pointing to the parent directory as the source root;
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For VS 2013 : `cmake -G "Visual Studio 12 2013 Win64" ../`
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For VS 2015 : `cmake -G "Visual Studio 14 2015 Win64" ../`
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NOTE: To see what supported Visual Studio outputs there are, run `cmake -G`
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1. open the 'EtcTest' solution
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1. make the 'EtcTool' project the start up project
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1. (optional) in the project properties, under 'Debugging ->command arguments'
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add the argfile textfile thats included in the EtcTool directory.
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example: -argfile C:\etc2\EtcTool\Args.txt
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### Setup For Linux
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The Linux build was tested on this config:
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Ubuntu desktop 14.04
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gcc/g++ 4.8
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cmake 2.8.12.2
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1. Verify linux has cmake and C++-11 capable g++ installed
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1. Open shell
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1. Run `mkdir build_linux`
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1. Run `cd build_linux`
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1. Run `cmake ../`
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1. Run `make`
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1. navigate to the newly created EtcTool directory `cd EtcTool`
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1. run the executable: `./EtcTool -argfile ../../EtcTool/args.txt`
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Skip to the <a href="#usage">Usage</a> section for more information about using the
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tool.
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## Usage
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### Command Line Usage
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EtcTool can be run from the command line with the following usage:
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etctool.exe source_image [options ...] -output encoded_image
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The encoder will use an array of RGBA floats read from the source_image to create
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an ETC1 or ETC2 encoded image in encoded_image. The RGBA floats should be in the
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range [0:1].
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Options:
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-analyze <analysis_folder>
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-argfile <arg_file> additional command line arguments read from a file
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-blockAtHV <H V> encodes a single block that contains the
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pixel specified by the H V coordinates
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-compare <comparison_image> compares source_image to comparison_image
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-effort <amount> number between 0 and 100 to specify the encoding quality
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(100 is the highest quality)
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-errormetric <error_metric> specify the error metric, the options are
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rgba, rgbx, rec709, numeric and normalxyz
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-format <etc_format> ETC1, RGB8, SRGB8, RGBA8, SRGB8, RGB8A1,
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SRGB8A1 or R11
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-help prints this message
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-jobs or -j <thread_count> specifies the number of threads (default=1)
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-normalizexyz normalize RGB to have a length of 1
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-verbose or -v shows status information during the encoding
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process
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-mipmaps or -m <mip_count> sets the maximum number of mipaps to generate (default=1)
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-mipwrap or -w <x|y|xy> sets the mipmap filter wrap mode (default=clamp)
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* -analyze will run an analysis of the encoding and place it in folder
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"analysis_folder" (e.g. ../analysis/kodim05). within the analysis_folder, a folder
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will be created with a name of the current date/time (e.g. 20151204_153306). this
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date/time folder is used to compare encodings of the same texture over time.
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within the date/time folder is a text file with several encoding stats and a 2x png
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image showing the encoding mode for each 4x4 block.
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* -argfile allows additional command line arguments to be placed in a text file
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* -blockAtHV selects the 4x4 pixel subset of the source image at position (H,V).
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This is mainly used for debugging
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* -compare compares the source image to the created encoded image. The encoding
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will dictate what error analysis is used in the comparison.
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* -effort uses an "amount" between 0 and 100 to determine how much additional effort
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to apply during the encoding.
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* -errormetric selects the fitting algorithm used by the encoder. "rgba" calculates
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RMS error using RGB components that are weighted by A. "rgbx" calculates RMS error
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using RGBA components, where A is treated as an additional data channel, instead of
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as alpha. "rec709" is similar to "rgba", except the RGB components are also weighted
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according to Rec709. "numeric" calculates RMS error using unweighted RGBA components.
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"normalize" calculates error based on dot product and vector length for RGB and RMS
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error for A.
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* -help prints out the usage message
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* -jobs enables multi-threading to speed up image encoding
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* -normalizexyz normalizes the source RGB to have a length of 1.
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* -verbose shows information on the current encoding process. It will then display the
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PSNR and time time it took to encode the image.
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* -mipmaps takes an argument that specifies how many mipmaps to generate from the
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source image. The mipmaps are generated with a lanczos3 filter using edge clamping.
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If the mipmaps option is not specified no mipmaps are created.
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* -mipwrap takes an argument that specifies the mipmap filter wrap mode. The options
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are "x", "y" and "xy" which specify wrapping in x only, y only or x and y respectively.
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The default options are clamping in both x and y.
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Note: Path names can use slashes or backslashes. The tool will convert the
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slashes to the appropriate polarity for the current platform.
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## API
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The library supports two different APIs - a C-like API that is not heavily
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class-based and a class-based API.
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main() in EtcTool.cpp contains an example of both APIs.
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The Encode() method now returns an EncodingStatus that contains bit flags for
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reporting various warnings and flags encountered when encoding.
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## Copyright
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Copyright 2015 Etc2Comp Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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