From f5ac652497f22b159b5e44bf69f44092ff91936b Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 18 Jun 2019 13:28:04 +0300
Subject: [PATCH] Only update the changed parts of VertexSetup

Besides being a minor optimization, this fixes a crash if update gets
called before both vertex array and index buffer are set.
---
 source/vertexsetup.cpp | 25 ++++++++++++++++---------
 source/vertexsetup.h   | 12 ++++++++++--
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/source/vertexsetup.cpp b/source/vertexsetup.cpp
index f6a71f49..275585be 100644
--- a/source/vertexsetup.cpp
+++ b/source/vertexsetup.cpp
@@ -10,7 +10,7 @@ namespace Msp {
 namespace GL {
 
 VertexSetup::VertexSetup():
-	dirty(false),
+	dirty(0),
 	array(0),
 	index_buffer(0)
 {
@@ -28,23 +28,32 @@ VertexSetup::~VertexSetup()
 void VertexSetup::set_vertex_array(const VertexArray &a)
 {
 	array = &a;
-	update();
+	update(VERTEX_ARRAY);
 }
 
 void VertexSetup::set_index_buffer(const Buffer &ibuf)
 {
 	index_buffer = &ibuf;
-	update();
+	update(INDEX_BUFFER);
 }
 
-void VertexSetup::update() const
+void VertexSetup::update(unsigned mask) const
 {
 	if(current()!=this)
 	{
-		dirty = true;
+		dirty |= mask;
 		return;
 	}
 
+	if(mask&VERTEX_ARRAY)
+		update_vertex_array();
+
+	if(mask&INDEX_BUFFER)
+		glBindBuffer(ELEMENT_ARRAY_BUFFER, index_buffer->get_id());
+}
+
+void VertexSetup::update_vertex_array() const
+{
 	Bind bind_vbuf(array->get_buffer(), ARRAY_BUFFER);
 
 	const VertexFormat &fmt = array->get_format();
@@ -63,8 +72,6 @@ void VertexSetup::update() const
 		glEnableVertexAttribArray(t);
 		ptr += sz;
 	}
-
-	glBindBuffer(ELEMENT_ARRAY_BUFFER, index_buffer->get_id());
 }
 
 void VertexSetup::bind() const
@@ -74,8 +81,8 @@ void VertexSetup::bind() const
 		glBindVertexArray(id);
 		if(dirty)
 		{
-			update();
-			dirty = false;
+			update(dirty);
+			dirty = 0;
 		}
 	}
 }
diff --git a/source/vertexsetup.h b/source/vertexsetup.h
index 466eed40..c4cadfca 100644
--- a/source/vertexsetup.h
+++ b/source/vertexsetup.h
@@ -15,8 +15,14 @@ objects.  Intended for internal use.
 class VertexSetup: public Bindable<VertexSetup>
 {
 private:
+	enum ComponentMask
+	{
+		VERTEX_ARRAY = 1,
+		INDEX_BUFFER = 2
+	};
+
 	unsigned id;
-	mutable bool dirty;
+	mutable unsigned dirty;
 	const VertexArray *array;
 	const Buffer *index_buffer;
 
@@ -25,11 +31,13 @@ public:
 	~VertexSetup();
 
 	void set_vertex_array(const VertexArray &);
+	void set_instance_array(const VertexArray &);
 	void set_index_buffer(const Buffer &);
 	const Buffer *get_index_buffer() const { return index_buffer; }
 
 private:
-	void update() const;
+	void update(unsigned) const;
+	void update_vertex_array() const;
 
 public:
 	void bind() const;
-- 
2.43.0