Add sky light, physical atmosphere, auto exposure and bloom to the GL 4.6 renderer

gl/readback.cpp

@@ -0,0 +1,51 @@
+#include "stdafx.h"
+#include "readback.h"
+
+gl::readback::readback(GLsizeiptr size) : m_size(size) {}
+
+gl::readback::~readback()
+{
+	for (auto &slot : m_slots)
+	{
+		// fences first, they belong to the copies
+		slot.copied.reset();
+		if (slot.buffer != 0)
+			glDeleteBuffers(1, &slot.buffer);
+	}
+}
+
+void gl::readback::push(GLuint Source, GLintptr Offset)
+{
+	if (m_used >= SLOTS)
+		return;
+
+	auto &slot{m_slots[(m_first + m_used) % SLOTS]};
+	if (slot.buffer == 0)
+	{
+		glCreateBuffers(1, &slot.buffer);
+		glNamedBufferStorage(slot.buffer, m_size, nullptr, GL_CLIENT_STORAGE_BIT);
+	}
+	glCopyNamedBufferSubData(Source, slot.buffer, Offset, 0, m_size);
+	slot.copied = std::make_unique<fence>();
+	++m_used;
+}
+
+bool gl::readback::pop(void *Data)
+{
+	bool result{false};
+	// oldest first, as long as the gpu has finished the copies; the newest finished one ends in Data
+	while (m_used > 0)
+	{
+		auto &slot{m_slots[m_first]};
+		if (!slot.copied->is_signalled())
+			break;
+
+		glGetNamedBufferSubData(slot.buffer, 0, m_size, Data);
+		slot.copied.reset();
+		result = true;
+
+		m_first = (m_first + 1) % SLOTS;
+		--m_used;
+	}
+	return result;
+}