[nostalgia] Break part of core out into Turbine and TeaGBA libraries

src/nostalgia/glutils/glutils.cpp

@@ -46,6 +46,24 @@ template struct GLObject<deleteVertexArray>;
 template struct GLObject<deleteProgram>;
 template struct GLObject<deleteShader>;
 
+const FrameBuffer *FrameBufferBind::s_activeFb = nullptr;
+
+FrameBufferBind::FrameBufferBind(const FrameBuffer &fb) noexcept: m_restoreFb(s_activeFb) {
+	s_activeFb = &fb;
+	glBindFramebuffer(GL_FRAMEBUFFER, fb);
+	glViewport(0, 0, fb.width, fb.height);
+}
+
+FrameBufferBind::~FrameBufferBind() noexcept {
+	s_activeFb = m_restoreFb;
+	if (s_activeFb) {
+		glBindFramebuffer(GL_FRAMEBUFFER, *s_activeFb);
+		glViewport(0, 0, s_activeFb->width, s_activeFb->height);
+	} else {
+		glBindFramebuffer(GL_FRAMEBUFFER, 0);
+		glViewport(0, 0, s_activeFb->width, s_activeFb->height);
+	}
+}
 
 void bind(const FrameBuffer &fb) noexcept {
 	glBindFramebuffer(GL_FRAMEBUFFER, fb);

src/nostalgia/glutils/glutils.hpp

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <ox/std/bounds.hpp>
 #include <ox/std/defines.hpp>
 
 #include <glad/glad.h>
@@ -134,6 +135,15 @@ struct FrameBuffer {
 	}
 };
 
+class FrameBufferBind {
+	private:
+		static const FrameBuffer *s_activeFb;
+		const FrameBuffer *m_restoreFb = nullptr;
+	public:
+		explicit FrameBufferBind(const FrameBuffer &fb) noexcept;
+		~FrameBufferBind() noexcept;
+};
+
 void bind(const FrameBuffer &fb) noexcept;