GLSL shader gen: Add alpha test (...half of it I guess)

include/PICA/pica_frag_config.hpp

@@ -0,0 +1,53 @@
+#pragma once
+#include <array>
+#include <cstring>
+#include <type_traits>
+#include <unordered_map>
+
+#include "PICA/pica_hash.hpp"
+#include "PICA/regs.hpp"
+#include "bitfield.hpp"
+#include "helpers.hpp"
+
+namespace PICA {
+	struct OutputConfig {
+		union {
+			u32 raw;
+			// Merge the enable + compare function into 1 field to avoid duplicate shaders
+			// enable == off means a CompareFunction of Always
+			BitField<0, 3, CompareFunction> alphaTestFunction;
+		};
+	};
+
+	struct TextureConfig {
+		u32 texUnitConfig;
+		u32 texEnvUpdateBuffer;
+
+		// TODO: This should probably be a uniform
+		u32 texEnvBufferColor;
+
+		// There's 6 TEV stages, and each one is configured via 5 word-sized registers
+		std::array<u32, 5 * 6> tevConfigs;
+	};
+
+	struct FragmentConfig {
+		OutputConfig outConfig;
+		TextureConfig texConfig;
+
+		bool operator==(const FragmentConfig& config) const {
+			// Hash function and equality operator required by std::unordered_map
+			return std::memcmp(this, &config, sizeof(FragmentConfig)) == 0;
+		}
+	};
+
+	static_assert(
+		std::has_unique_object_representations<OutputConfig>() && std::has_unique_object_representations<TextureConfig>() &&
+		std::has_unique_object_representations<FragmentConfig>()
+	);
+}  // namespace PICA
+
+// Override std::hash for our fragment config class
+template <>
+struct std::hash<PICA::FragmentConfig> {
+	std::size_t operator()(const PICA::FragmentConfig& config) const noexcept { return PICAHash::computeHash((const char*)&config, sizeof(config)); }
+};