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Reworked conditions, added uber-shaders, comparison nodes, fixed Discard

src/Nazara/Graphics/UberShader.cpp

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+// Copyright (C) 2017 Jérôme Leclercq
+// This file is part of the "Nazara Engine - Graphics module"
+// For conditions of distribution and use, see copyright notice in Config.hpp
+
+#include <Nazara/Graphics/UberShader.hpp>
+#include <Nazara/Graphics/Graphics.hpp>
+#include <Nazara/Renderer/RenderDevice.hpp>
+#include <Nazara/Shader/ShaderAst.hpp>
+#include <limits>
+#include <stdexcept>
+#include <Nazara/Graphics/Debug.hpp>
+
+namespace Nz
+{
+	UberShader::UberShader(ShaderAst shaderAst) :
+	m_shaderAst(std::move(shaderAst))
+	{
+		std::size_t conditionCount = m_shaderAst.GetConditionCount();
+
+		if (conditionCount >= 64)
+			throw std::runtime_error("Too many conditions");
+
+		m_combinationMask = std::numeric_limits<UInt64>::max();
+		m_combinationMask <<= conditionCount;
+		m_combinationMask = ~m_combinationMask;
+	}
+
+	UInt64 UberShader::GetConditionFlagByName(const std::string_view& condition) const
+	{
+		std::size_t conditionIndex = m_shaderAst.FindConditionByName(condition);
+		if (conditionIndex != ShaderAst::InvalidCondition)
+			return SetBit<UInt64>(0, conditionIndex);
+		else
+			return 0;
+	}
+
+	const std::shared_ptr<ShaderStage>& UberShader::Get(UInt64 combination)
+	{
+		combination &= m_combinationMask;
+
+		auto it = m_combinations.find(combination);
+		if (it == m_combinations.end())
+		{
+			ShaderWriter::States states;
+			states.enabledConditions = combination;
+
+			std::shared_ptr<ShaderStage> stage = Graphics::Instance()->GetRenderDevice().InstantiateShaderStage(m_shaderAst, std::move(states));
+
+			it = m_combinations.emplace(combination, std::move(stage)).first;
+		}
+
+		return it->second;
+	}
+}