kicad/cmake/BuildSteps/CreateShaderCpp.cmake

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#
# Converts provided shader files into the gal namespaced shaders
#
# The goal here is to convert the contents of shaders in the source tree
# into strings to embed into the binaries rather than loading from disk.
#
# We convert the shaders to binary form in the header due limitations of string literal
# lengths and also because future development options such as moving to bgfx
# results in precompiled binary shaders we need to store
#
# This file is structured to be invoked from add_custom_command in order
# to have GENERATED marked output files that can be rebuilt on change.
#
# Required Arguments:
# SOURCE_FILE - Path to source shader file
# OUT_CPP_DIR - Destination path for cpp file
# OUT_HEADER_DIR - Destination path for header file
# OUT_CPP_FILENAME - cpp filename
# OUT_HEADER_FILENAME - header filename
# OUT_VAR_NAME - Name of variable containing shader to be created
#
# Parts taken from https://github.com/sivachandran/cmake-bin2h
# Copyright 2020 Sivachandran Paramasivam
#
# Function to wrap a given string into multiple lines at the given column position.
# Parameters:
# VARIABLE - The name of the CMake variable holding the string.
# AT_COLUMN - The column position at which string will be wrapped.
function(WRAP_STRING)
set(oneValueArgs VARIABLE AT_COLUMN)
cmake_parse_arguments(WRAP_STRING "${options}" "${oneValueArgs}" "" ${ARGN})
string(LENGTH ${${WRAP_STRING_VARIABLE}} stringLength)
math(EXPR offset "0")
while(stringLength GREATER 0)
if(stringLength GREATER ${WRAP_STRING_AT_COLUMN})
math(EXPR length "${WRAP_STRING_AT_COLUMN}")
else()
math(EXPR length "${stringLength}")
endif()
string(SUBSTRING ${${WRAP_STRING_VARIABLE}} ${offset} ${length} line)
set(lines "${lines}\n${line}")
math(EXPR stringLength "${stringLength} - ${length}")
math(EXPR offset "${offset} + ${length}")
endwhile()
set(${WRAP_STRING_VARIABLE} "${lines}" PARENT_SCOPE)
endfunction()
file( READ ${SOURCE_FILE} _SOURCE_BINARY HEX )
string(LENGTH ${_SOURCE_BINARY} _SOURCE_BINARY_LENGTH)
set(SOURCE_BINARY "${_SOURCE_BINARY}00") # null terminate for the sake of it
wrap_string(VARIABLE _SOURCE_BINARY AT_COLUMN 32)
math(EXPR _ARRAY_SIZE "${_SOURCE_BINARY_LENGTH} / 2")
# adds '0x' prefix and comma suffix before and after every byte respectively
string(REGEX REPLACE "([0-9a-f][0-9a-f])" "0x\\1, " _ARRAY_VALUES ${_SOURCE_BINARY})
# removes trailing comma
string(REGEX REPLACE ", $" "" _ARRAY_VALUES ${_ARRAY_VALUES})
set( outCppTextByteArray "unsigned char ${OUT_VAR_NAME}_bytes[] = { ${_ARRAY_VALUES} };")
set( outCppTextStdString "std::string ${OUT_VAR_NAME} = std::string( reinterpret_cast<char const*>(${OUT_VAR_NAME}_bytes), ${_ARRAY_SIZE} ) ;")
set( outCppText
"
#include <string>
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#include <${OUT_HEADER_FILENAME}>
namespace KIGFX {
namespace BUILTIN_SHADERS {
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${outCppTextByteArray}
${outCppTextStdString}
}
}
" )
file(
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WRITE ${OUT_CPP_DIR}/${OUT_CPP_FILENAME}
"${outCppText}"
)
set( outHeaderText
"namespace KIGFX {
namespace BUILTIN_SHADERS {
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extern std::string ${OUT_VAR_NAME};
}
}"
)
file(
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WRITE ${OUT_HEADER_DIR}/${OUT_HEADER_FILENAME}
"${outHeaderText}"
)
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message(STATUS "Shader ${SOURCE_FILE} converted to ${OUT_CPP_DIR}/${OUT_CPP_FILENAME}")