store vertices in 1 big buffer

include/renderer_mtl/mtl_vertex_buffer_cache.hpp

@@ -0,0 +1,71 @@
+#pragma once
+
+#include <map>
+#include "pica_to_mtl.hpp"
+
+using namespace PICA;
+
+namespace Metal {
+
+struct BufferHandle {
+    MTL::Buffer* buffer;
+    size_t offset;
+};
+
+// 64MB buffer for caching vertex data
+#define CACHE_BUFFER_SIZE 64 * 1024 * 1024
+
+class VertexBufferCache {
+public:
+    VertexBufferCache() = default;
+
+    ~VertexBufferCache() {
+        clear();
+    }
+
+    void set(MTL::Device* dev) {
+        device = dev;
+        buffer = device->newBuffer(CACHE_BUFFER_SIZE, MTL::ResourceStorageModeShared);
+    }
+
+    void endFrame() {
+        ptr = 0;
+        for (auto buffer : additionalAllocations) {
+            buffer->release();
+        }
+        additionalAllocations.clear();
+    }
+
+    BufferHandle get(const std::span<const PICA::Vertex>& vertices) {
+        // If the vertex buffer is too large, just create a new one
+        if (ptr + vertices.size_bytes() > CACHE_BUFFER_SIZE) {
+            MTL::Buffer* newBuffer = device->newBuffer(vertices.data(), vertices.size_bytes(), MTL::ResourceStorageModeShared);
+            additionalAllocations.push_back(newBuffer);
+            Helpers::warn("Vertex buffer doesn't have enough space, creating a new buffer");
+
+            return BufferHandle{newBuffer, 0};
+        }
+
+        // Copy the data into the buffer
+        memcpy((char*)buffer->contents() + ptr, vertices.data(), vertices.size_bytes());
+
+        size_t oldPtr = ptr;
+        ptr += vertices.size_bytes();
+
+        return BufferHandle{buffer, oldPtr};
+    }
+
+    void clear() {
+        endFrame();
+        buffer->release();
+    }
+
+private:
+    MTL::Buffer* buffer;
+    size_t ptr = 0;
+    std::vector<MTL::Buffer*> additionalAllocations;
+
+    MTL::Device* device;
+};
+
+} // namespace Metal