Add a unified cross platform OpenGL core profile binding (#52)

1 files changed, 430 insertions, 0 deletions

diff --git a/scripts/BindingGenerator.lua b/scripts/BindingGenerator.lua
new file mode 100755
index 0000000..a1f2f2c
--- /dev/null
+++ b/scripts/BindingGenerator.lua
@@ -0,0 +1,430 @@
+#!/usr/bin/lua
+-- BindingGenerator.lua (c) hecks 2021
+-- This script is a part of IrrlichtMT, released under the same license.
+
+-- By default we assume you're running this from /scripts/
+-- and that you have the necessary headers there (gitignored for your convenience)
+local sourceTreePath = os.getenv( "IRRMTREPO" ) or "..";
+-- Otherwise run this from wherever you want and set the above env variable.
+local glHeaderPath = os.getenv( "GLHEADERPATH" ) or ".";
+-- GL headers will be looked for in the current directory or GLHEADERPATH.
+-- At the moment we require:
+-- 		"glcorearb.h"
+-- 		"gl2ext.h"
+-- Files other than glcorearb.h are only parsed for vendor specific defines
+-- and aliases. Otherwise we only use what exists in glcorearb.h, further
+-- restricted to procedures that are either core or ARB.
+
+
+-- Emulate a portion of the libraries that this was written against.
+getmetatable( "" ).__index = string;
+getmetatable( "" ).__len = string.len;
+getmetatable( "" ).__call = string.format;
+function string:Split( pat )
+	local r = {};
+	local pos = 1;
+	local from, to;
+	while pos and pos <= #self do
+		from, to = self:find( pat, pos );
+		if not from then
+			break;
+		end
+		r[#r+1] = self:sub( pos, from - 1 );
+		pos = to + 1;
+	end
+	r[#r+1] = self:sub( pos, #self );
+	return r;
+end
+function string:TrimBothEnds()
+	return self:gsub("^%s+",""):gsub("%s+$","");
+end
+local List;
+List = function( t )
+	return setmetatable( t or {}, {
+		__index = {
+			Add = function( t, v )
+				t[#t+1] = v;
+			end;
+			AddFormat = function( t, str, ... )
+				t:Add( str( ... ) );
+			end;
+			Where = function( t, f )
+				local r = {};
+				for i=1, #t do
+					if f(t[i]) then r[#r+1] = t[i]; end
+				end
+				return List( r );
+			end;
+			Select = function( t, f )
+				local r = {};
+				for i=1, #t do
+					r[#r+1] = f( t[i] );
+				end
+				return List( r );
+			end;
+			Join = function( t, n )
+				local r = {};
+				for i=1, #t do
+					r[i] = t[i];
+				end
+				for i=1, #n do
+					r[#r+1] = n[i];
+				end
+				return List( r );
+			end;
+			Concat = table.concat;
+		};
+	} );
+end
+
+
+------------ Header parsing ------------
+
+-- GL and GLES alike
+local driverVendors = {
+	"NV", "AMD", "INTEL", "OVR", "QCOM", "IMG", "ANGLE", "APPLE", "MESA"
+}
+local vendorSuffixes = {
+	"ARB", "EXT", "KHR", "OES",
+	unpack( driverVendors )
+};
+local vendorSuffixPattern = {};
+local constSuffixPattern = {};
+for i=1, #vendorSuffixes do
+	vendorSuffixPattern[i] = vendorSuffixes[i] .. "$";
+	constSuffixPattern[i] = ("_%s$")( vendorSuffixes[i] );
+end
+local constBanned = {};
+for i=1, #driverVendors do
+	constBanned[driverVendors[i]] = true;
+end
+-- Strip the uppercase extension vendor suffix from a name.
+local function StripVendorSuffix( str, const )
+	local patterns = const and constSuffixPattern or vendorSuffixPattern;
+	local n;
+	for i=1, #patterns do
+		str, n = str:gsub( patterns[i], "" );
+		if n > 0 then
+			return str, vendorSuffixes[i];
+		end
+	end
+	return str;
+end
+
+-- Normalize the type of an argument or return, also stripping any suffix
+-- and normalizing all whitespace regions to single spaces.
+local function NormalizeType( str )
+	local chunks = str:Split( "%s+" );
+	for j=1, #chunks do
+		chunks[j] = StripVendorSuffix( chunks[j] );
+	end
+	local T = table.concat(chunks, " " );
+	return T:TrimBothEnds();
+end
+
+-- Normalize an argument, returning the normalized type and the name separately,
+-- always sticking the * of a pointer to the type rather than the name.
+-- We need this to generate a normalized arg list and function signature (below)
+local function NormalizeArgument( str )
+	local chunks = str:Split( "%s+" );
+	for j=1, #chunks do
+		chunks[j] = StripVendorSuffix( chunks[j] );
+	end
+	local last = chunks[#chunks];
+	local name = last:match( "[%w_]+$" );
+	chunks[#chunks] = #name ~= #last and last:sub( 1, #last-#name) or nil;
+	local T = table.concat(chunks, " " ):TrimBothEnds();
+	return T, name
+end
+
+-- Normalize an argument list so that two matching prototypes
+-- will produce the same table if fed to this function.
+local function NormalizeArgList( str )
+	local args = str:Split( ",%s*" );
+	local r = {};
+	for i=1, #args do
+		local T, name = NormalizeArgument( args[i] );
+		r[i] = { T, name };
+	end
+	return r;
+end
+
+-- Normalize a function signature into a unique string for keying
+-- in such a way that if two different GL procedures may be assigned
+-- to the same function pointer, this will produce an identical string for both.
+-- This makes it possible to detect function aliases that may work as a fallback.
+-- You still have to check for the appropriate extension.
+local function NormalizeFunctionSignature( T, str )
+	local args = str:Split( ",%s*" );
+	local r = {};
+	for i=1, #args do
+		r[i] = NormalizeArgument( args[i] );
+	end
+	return ("%s(%s)")( T, table.concat( r, ", " ) );
+end
+
+-- Mangle the PFN name so that we don't collide with a
+-- typedef from any of the GL headers.
+local pfnFormat = "PFNGL%sPROC_MT";
+
+--( T, name, args )
+local typedefFormat = "\ttypedef %s (APIENTRYP %s) (%s);"
+-- Generate a PFN...GL style typedef for a procedure
+--
+local function GetProcedureTypedef( proc )
+	local args = {};
+	for i=1, #proc.args do
+		args[i] = ("%s %s")( unpack( proc.args[i] ) )
+	end
+	return typedefFormat( proc.retType, pfnFormat( proc.name:upper() ), table.concat( args, ", " ) );
+end
+
+local procedures = List();
+local nameset = {};
+local definitions = List();
+local consts = List();
+
+--[[
+	Structured procedure representation:
+
+	ProcSpec = {
+		string name;		-- Normalized name as it appears in the GL spec
+		string? vendor;		-- Uppercase vendor string (ARB, EXT, AMD, NV etc)
+		string signature;
+		string retType;
+		args = { { type, name } };
+	};
+]]
+-- Parse a whole header, extracting the data.
+local function ParseHeader( path, into, apiRegex, defs, consts, nameSet, noNewNames )
+	defs:AddFormat( "\t// %s", path );
+	local f = assert( io.open( path, "r" ), "Could not open " .. path );
+	for line in f:lines() do
+		-- Do not parse PFN typedefs; they're easily reconstructible.
+		local T, rawName, args = line:match( apiRegex );
+		if T then
+			T = NormalizeType( T );
+			-- Strip the 'gl' namespace prefix.
+			local procName = rawName:sub(3,-1);
+			local name, vendor = StripVendorSuffix( procName );
+			if not (noNewNames and nameSet[name]) then
+				nameSet[name] = true;
+				into:Add{
+					name = name;
+					vendor = vendor;
+					-- pfnType = pfnFormat( procName:upper() );
+					signature = NormalizeFunctionSignature( T, args );
+					retType = T;
+					args = NormalizeArgList( args );
+				};
+			end
+		elseif ( line:find( "#" ) and not line:find( "#include" ) ) then
+			local rawName, value = line:match( "#define%s+GL_([_%w]+)%s+0x(%w+)" );
+			if rawName and value then
+				local name, vendor = StripVendorSuffix( rawName, true );
+				if not constBanned[vendor] then
+					consts:Add{ name = name, vendor = vendor, value = "0x"..value };
+				end
+			end
+			::skip::
+		elseif( line:find( "typedef" ) and not line:find( "%(" ) ) then
+			-- Passthrough non-PFN typedefs
+			defs:Add( "\t" .. line );
+		end
+	end
+	defs:Add "";
+	f:close();
+end
+
+------------ Parse the headers ------------
+
+-- ES/gl2.h is a subset of glcorearb.h and does not need parsing.
+
+local funcRegex = "GLAPI%s+(.+)APIENTRY%s+(%w+)%s*%((.*)%)";
+local funcRegexES = "GL_APICALL%s+(.+)GL_APIENTRY%s+(%w+)%s*%((.*)%)";
+ParseHeader( glHeaderPath .. "/glcorearb.h", procedures, funcRegex, definitions, consts, nameset );
+ParseHeader( glHeaderPath .. "/gl2ext.h", procedures, funcRegexES, List(), consts, nameset, true );
+-- Typedefs are redirected to a dummy list here on purpose.
+-- The only unique typedef from gl2ext is this:
+definitions:Add "\ttypedef void *GLeglClientBufferEXT;";
+
+------------ Sort out constants ------------
+
+local cppConsts = List();
+do
+	local constBuckets = {};
+	for i=1, #consts do
+		local vendor = consts[i].vendor or "core";
+		constBuckets[consts[i].name] = constBuckets[consts[i].name] or {};
+		constBuckets[consts[i].name][vendor] = consts[i].value;
+	end
+	local names = {};
+	for i=1, #consts do
+		local k = consts[i].name;
+		local b = constBuckets[k];
+		if k == "WAIT_FAILED" or k == "DIFFERENCE" then
+			-- This is why using #define as const is evil.
+			k = "_" .. k;
+		end
+		if b and not names[k] then
+			names[k] = true;
+			-- I have empirically tested that constants in GL with the same name do not differ,
+			-- at least for these suffixes.
+			local v = b.core or b.KHR or b.ARB or b.OES or b.EXT;
+			if v then
+				local T = v:find( "ull" ) and "GLuint64" or "GLenum";
+				cppConsts:AddFormat( "\tstatic constexpr const %s %s = %s;", T, k, v );
+			end
+		end
+	end
+end
+
+
+------------ Sort out procedures ------------
+
+local procTable = {};
+
+local coreProcedures = procedures:Where( function(x) return not x.vendor; end );
+local arbProcedures = procedures:Where( function(x) return x.vendor == "ARB"; end );
+
+-- Only consider core and ARB functions.
+local nameList = coreProcedures:Join( arbProcedures ):Select(
+	function(p)
+		return p.name;
+	end );
+
+local nameSet = {};
+local uniqueNames = List();
+
+for s, k in ipairs( nameList ) do
+	if not nameSet[k] then
+		nameSet[k] = true;
+		uniqueNames:Add( k );
+	end
+end
+
+for i=1, #procedures do
+	local p = procedures[i];
+	procTable[p.name] = procTable[p.name] or {};
+	local key = p.vendor or "core";
+	procTable[p.name][key] = p;
+end
+
+local priorityList = List{ "core", "ARB", "OES", "KHR" };
+
+local typedefs = List();
+local pointers = List();
+local loader = List();
+
+for s, str in ipairs( uniqueNames ) do
+	pointers:Add( ("\t%s %s = NULL;")( pfnFormat( str:upper() ), str ) );
+	local typeDefGenerated = false;
+	for i=1, #priorityList do
+		local k = priorityList[i];
+		local proc = procTable[str][k]
+		if proc then
+			if not typeDefGenerated then
+				typedefs:Add( GetProcedureTypedef( proc ) );
+				typeDefGenerated = true;
+			end
+			local vendor = k == "core" and "" or k;
+			loader:AddFormat(
+				'\tif (!%s) %s = (%s)cmgr->getProcAddress("%s");\n',
+				str, str, pfnFormat( proc.name:upper() ), ("gl%s%s")(str,vendor)
+			);
+		end
+	end
+end
+
+
+------------ Write files ------------
+
+-- Write loader header
+local f = io.open( sourceTreePath .. "/include/mt_opengl.h", "wb" );
+f:write[[
+// This code was generated by scripts/BindingGenerator.lua
+// Do not modify it, modify and run the generator instead.
+
+#pragma once
+
+#include <string>
+#include <unordered_set>
+#include "IrrCompileConfig.h"
+#include "irrTypes.h"
+#include "IContextManager.h"
+#include <KHR/khrplatform.h>
+
+#ifndef APIENTRY
+	#define APIENTRY
+#endif
+#ifndef APIENTRYP
+	#define APIENTRYP APIENTRY *
+#endif
+#ifndef GLAPI
+	#define GLAPI extern
+#endif
+
+]];
+
+f:write[[
+class OpenGLProcedures {
+private:
+]];
+f:write( definitions:Concat( "\n" ) );
+f:write( "\n" );
+f:write[[
+	// The script will miss this particular typedef thinking it's a PFN,
+	// so we have to paste it in manually. It's the only such type in OpenGL.
+	typedef void (APIENTRY *GLDEBUGPROC)
+		(GLenum source,GLenum type,GLuint id,GLenum severity,GLsizei length,const GLchar *message,const void *userParam);
+
+]]
+f:write( typedefs:Concat( "\n" ) );
+f:write( "\n\n" );
+f:write [[
+	std::unordered_set<std::string> extensions;
+public:
+	// Call this once after creating the context.
+	void LoadAllProcedures(irr::video::IContextManager *cmgr);
+	// Check if an extension is supported.
+	inline bool IsExtensionPresent(const std::string &ext)
+	{
+		return extensions.find(ext) != extensions.end();
+	}
+
+]];
+f:write( pointers:Concat( "\n" ) );
+f:write( "\n\n" );
+f:write( cppConsts:Concat( "\n" ) );
+f:write( "\n\n" );
+f:write( "};\n" );
+f:write( "\n//Global GL procedures object.\n" );
+f:write( "IRRLICHT_API extern OpenGLProcedures GL;\n" );
+f:close();
+
+-- Write loader implementation
+f = io.open( sourceTreePath .. "/source/Irrlicht/mt_opengl_loader.cpp", "wb" );
+f:write[[
+#include "mt_opengl.h"
+#include <string>
+#include <sstream>
+
+OpenGLProcedures GL = OpenGLProcedures();
+
+void OpenGLProcedures::LoadAllProcedures(irr::video::IContextManager *cmgr)
+{
+
+]];
+f:write( loader:Concat() );
+f:write[[
+
+	// get the extension string, chop it up
+	std::string ext_string = std::string((char*)GetString(EXTENSIONS));
+	std::stringstream ext_ss(ext_string);
+	std::string tmp;
+	while (std::getline(ext_ss, tmp, ' '))
+		extensions.emplace(tmp);
+
+}
+]];
+f:close();