Function define_entry_point

source/effect_codegen_hlsl.cpp:1190–1340

	}

	void define_entry_point(function &func) override
	{
		// Modify entry point name since a new function is created for it below
		assert(!func.unique_name.empty() && func.unique_name[0] == 'F');
		if (_shader_model < 40 || func.type == shader_type::compute)
			func.unique_name[0] = 'E';

		if (func.type == shader_type::compute)
			func.unique_name +=
				'_' + std::to_string(func.num_threads[0]) +
				'_' + std::to_string(func.num_threads[1]) +
				'_' + std::to_string(func.num_threads[2]);

		if (std::find_if(_module.entry_points.begin(), _module.entry_points.end(),
				[&func](const std::pair<std::string, shader_type> &entry_point) {
					return entry_point.first == func.unique_name;
				}) != _module.entry_points.end())
			return;

		_module.entry_points.emplace_back(func.unique_name, func.type);

		// Only have to rewrite the entry point function signature in shader model 3 and for compute (to write "numthreads" attribute)
		if (_shader_model >= 40 && func.type != shader_type::compute)
			return;

		function entry_point = func;
		entry_point.referenced_functions.push_back(func.id);

		const auto is_color_semantic = [](const std::string &semantic) {
			return semantic.compare(0, 9, "SV_TARGET") == 0 || semantic.compare(0, 5, "COLOR") == 0; };
		const auto is_position_semantic = [](const std::string &semantic) {
			return semantic == "SV_POSITION" || semantic == "POSITION"; };

		const id ret = make_id();
		define_name<naming::general>(ret, "ret");

		std::string position_variable_name;
		{
			if (func.type == shader_type::vertex && func.return_type.is_struct())
			{
				// If this function returns a struct which contains a position output, keep track of its member name
				for (const member_type &member : get_struct(func.return_type.struct_definition).member_list)
					if (is_position_semantic(member.semantic))
						position_variable_name = id_to_name(ret) + '.' + member.name;
			}

			if (is_color_semantic(func.return_semantic))
			{
				// The COLOR output semantic has to be a four-component vector in shader model 3, so enforce that
				entry_point.return_type.rows = 4;
			}
			if (is_position_semantic(func.return_semantic))
			{
				if (func.type == shader_type::vertex)
					// Keep track of the position output variable
					position_variable_name = id_to_name(ret);
			}
		}