use depth stencil render target

include/renderer_mtl/mtl_depth_stencil_cache.hpp

@@ -0,0 +1,55 @@
+#pragma once
+
+#include "pica_to_mtl.hpp"
+
+using namespace PICA;
+
+namespace Metal {
+
+struct DepthStencilHash {
+    bool depthWrite;
+    u8 depthFunc;
+};
+
+class DepthStencilCache {
+public:
+    DepthStencilCache() = default;
+
+    ~DepthStencilCache() {
+        clear();
+    }
+
+    void set(MTL::Device* dev) {
+        device = dev;
+    }
+
+    MTL::DepthStencilState* get(DepthStencilHash hash) {
+        u8 intHash = hash.depthWrite | (hash.depthFunc << 1);
+        auto& depthStencilState = depthStencilCache[intHash];
+        if (!depthStencilState) {
+            MTL::DepthStencilDescriptor* desc = MTL::DepthStencilDescriptor::alloc()->init();
+            desc->setDepthWriteEnabled(hash.depthWrite);
+            desc->setDepthCompareFunction(toMTLCompareFunc(hash.depthFunc));
+
+            depthStencilState = device->newDepthStencilState(desc);
+
+            desc->release();
+        }
+
+        return depthStencilState;
+    }
+
+    void clear() {
+        for (auto& pair : depthStencilCache) {
+            pair.second->release();
+        }
+        depthStencilCache.clear();
+    }
+
+private:
+    std::unordered_map<u8, MTL::DepthStencilState*> depthStencilCache;
+
+    MTL::Device* device;
+};
+
+} // namespace Metal