From 0c00505d44c86bdbee238abbefee74d93f80f29b Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 12 Dec 2020 16:04:10 +0300
Subject: [PATCH] Add OpenGL query helper

---
 libs/gfx/include/psemek/gfx/query.hpp | 86 +++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100644 libs/gfx/include/psemek/gfx/query.hpp

diff --git a/libs/gfx/include/psemek/gfx/query.hpp b/libs/gfx/include/psemek/gfx/query.hpp
new file mode 100644
index 00000000..5496999a
--- /dev/null
+++ b/libs/gfx/include/psemek/gfx/query.hpp
@@ -0,0 +1,86 @@
+#pragma once
+
+#include <psemek/gfx/gl.hpp>
+
+#include <vector>
+
+namespace psemek::gfx
+{
+
+	struct query_array
+	{
+		query_array() = default;
+		query_array(std::size_t size);
+		~query_array();
+
+		std::size_t size() const { return ids_.size(); }
+
+		void resize(std::size_t size);
+
+		GLuint operator[](std::size_t i) const;
+
+		struct query_scope
+		{
+			GLenum type;
+
+			query_scope(GLenum type)
+				: type{type}
+			{}
+
+			query_scope(query_scope const &) = delete;
+			query_scope(query_scope &&) = delete;
+
+			query_scope & operator = (query_scope const &) = delete;
+			query_scope & operator = (query_scope &&) = delete;
+
+			~query_scope()
+			{
+				gl::EndQuery(type);
+			}
+		};
+
+		query_scope begin(std::size_t i, GLenum type) const;
+
+	private:
+		std::vector<GLuint> ids_;
+	};
+
+	inline query_array::query_array(std::size_t size)
+		: ids_(size)
+	{
+		gl::GenQueries(size, ids_.data());
+	}
+
+	inline query_array::~query_array()
+	{
+		gl::DeleteQueries(ids_.size(), ids_.data());
+		ids_.clear();
+	}
+
+	inline void query_array::resize(std::size_t size)
+	{
+		if (size < ids_.size())
+		{
+			gl::DeleteQueries(ids_.size() - size, ids_.data() + size);
+			ids_.resize(size);
+		}
+		else if (size > ids_.size())
+		{
+			std::size_t old_size = ids_.size();
+			ids_.resize(size);
+			gl::GenQueries(size - old_size, ids_.data() + old_size);
+		}
+	}
+
+	inline GLuint query_array::operator[](std::size_t i) const
+	{
+		return ids_[i];
+	}
+
+	inline query_array::query_scope query_array::begin(std::size_t i, GLenum type) const
+	{
+		gl::BeginQuery(type, ids_[i]);
+		return query_scope{type};
+	}
+
+}