feat(terrain): binary terrain files (.btf) made out of text terrain files (.txtf) named by terrain directives, checked against length and checksum of the text and loaded section by section when needed; -btf command line conversion; SBT files no longer generated, only loaded

scene/sceneterrain.h

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+/*
+This Source Code Form is subject to the
+terms of the Mozilla Public License, v.
+2.0. If a copy of the MPL was not
+distributed with this file, You can
+obtain one at
+http://mozilla.org/MPL/2.0/.
+*/
+
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+namespace scene
+{
+
+class basic_region;
+class basic_section;
+struct terrain_block;
+
+// binary terrain file (.btf): static geometry of a text terrain file (.txtf), arranged by the sections
+// of the scene so each can be loaded on its own, when it comes into use.
+// the binary file records length and checksum of the text it was made from, and is made anew when these don't match
+class terrain_file
+{
+  public:
+	// types
+	// what a scenery is left with for a terrain file it refers to
+	enum class state
+	{
+		binary, // binary file is in place and up to date
+		text, // binary file can't be had, the text file has to be loaded the way any other scenery file is
+		missing // there's nothing to load
+	};
+	// methods
+	// calculates checksum (crc-32) of provided data
+	static std::uint32_t checksum(char const *Data, std::size_t Size);
+	// converts specified text terrain file to binary format. returns: true on success, false otherwise.
+	// description of the result or of the failure is stored in Message, if provided
+	static bool convert(std::string const &Textfile, std::string const &Binaryfile, std::string *Message = nullptr);
+	// makes sure binary version of specified text terrain file is in place and matches the text
+	static state prepare(std::string const &Textfile, std::string const &Binaryfile);
+	// makes content of specified binary terrain file a part of provided region. the geometry is loaded right away,
+	// or left for the sections of the region to load when they're about to be used. returns: true on success, false otherwise
+	static bool attach(std::string const &Binaryfile, basic_region &Region, bool Deferred);
+	// loads specified piece of a binary terrain file into provided section
+	static void load(basic_section &Section, terrain_block const &Block);
+
+  private:
+	// converts provided content of a text terrain file to binary format and stores it in specified file. returns: true on success, false otherwise
+	static bool write(std::string const &Text, std::string const &Binaryfile, std::string &Message);
+};
+
+} // namespace scene
+
+//---------------------------------------------------------------------------