From 3e38e8a7bfffb0b6d622b849b402f4f04a7536c4 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Tue, 14 Sep 2021 00:17:12 +0300
Subject: [PATCH] Simplify pipeline state management

Instead of unbinding things immediately, defer it to when the state is
cleared.  This results in less binding calls overall.  The only reason
to unbind anything is to allow those objects to be destroyed, and that
shouldn't happen in the middle of rendering anyway.
---
 source/core/pipelinestate.cpp | 93 ++++++++---------------------------
 source/core/pipelinestate.h   |  1 +
 2 files changed, 21 insertions(+), 73 deletions(-)

diff --git a/source/core/pipelinestate.cpp b/source/core/pipelinestate.cpp
index 0d91f759..f855eed6 100644
--- a/source/core/pipelinestate.cpp
+++ b/source/core/pipelinestate.cpp
@@ -26,6 +26,7 @@ namespace GL {
 
 const PipelineState *PipelineState::last_applied = 0;
 vector<int> PipelineState::bound_tex_targets;
+vector<char> PipelineState::bound_uniform_blocks;
 unsigned PipelineState::restart_index = 0;
 
 PipelineState::PipelineState():
@@ -42,8 +43,10 @@ PipelineState::PipelineState():
 	blend(0),
 	changes(0)
 {
-	if(!ARB_direct_state_access && bound_tex_targets.empty())
+	if(bound_tex_targets.empty())
 		bound_tex_targets.resize(Limits::get_global().max_texture_bindings);
+	if(bound_uniform_blocks.empty())
+		bound_uniform_blocks.resize(Limits::get_global().max_uniform_bindings);
 }
 
 PipelineState::~PipelineState()
@@ -242,35 +245,6 @@ void PipelineState::apply(unsigned mask) const
 
 	if(mask&TEXTURES)
 	{
-		if(last_applied && this!=last_applied)
-		{
-			vector<BoundTexture>::const_iterator i = textures.begin();
-			vector<BoundTexture>::const_iterator j = last_applied->textures.begin();
-			while(j!=last_applied->textures.end())
-			{
-				if(i==textures.end() || j->binding<i->binding)
-				{
-					if(bound_tex_targets[j->binding])
-					{
-						if(ARB_direct_state_access)
-							glBindTextureUnit(j->binding, 0);
-						else
-						{
-							glActiveTexture(GL_TEXTURE0+j->binding);
-							glBindTexture(bound_tex_targets[j->binding], 0);
-						}
-					}
-					++j;
-				}
-				else
-				{
-					if(i->binding==j->binding)
-						++j;
-					++i;
-				}
-			}
-		}
-
 		for(vector<BoundTexture>::const_iterator i=textures.begin(); i!=textures.end(); ++i)
 			if(i->changed || mask==~0U)
 			{
@@ -284,23 +258,13 @@ void PipelineState::apply(unsigned mask) const
 						if(bound_tex_targets[i->binding] && static_cast<int>(i->texture->get_target())!=bound_tex_targets[i->binding])
 							glBindTexture(bound_tex_targets[i->binding], 0);
 						glBindTexture(i->texture->get_target(), i->texture->get_id());
-						bound_tex_targets[i->binding] = i->texture->get_target();
 					}
 
+					bound_tex_targets[i->binding] = i->texture->get_target();
+
 					glBindSampler(i->binding, i->sampler->get_id());
 					i->sampler->refresh();
 				}
-				else if(bound_tex_targets[i->binding])
-				{
-					if(ARB_direct_state_access)
-						glBindTextureUnit(i->binding, 0);
-					else
-					{
-						glActiveTexture(GL_TEXTURE0+i->binding);
-						glBindTexture(bound_tex_targets[i->binding], 0);
-						bound_tex_targets[i->binding] = 0;
-					}
-				}
 
 				i->changed = false;
 			}
@@ -308,26 +272,6 @@ void PipelineState::apply(unsigned mask) const
 
 	if(mask&UNIFORMS)
 	{
-		if(last_applied && this!=last_applied)
-		{
-			vector<BoundUniformBlock>::const_iterator i = uniform_blocks.begin();
-			vector<BoundUniformBlock>::const_iterator j = last_applied->uniform_blocks.begin();
-			while(j!=last_applied->uniform_blocks.end())
-			{
-				if(i==uniform_blocks.end() || j->binding<i->binding)
-				{
-					glBindBufferBase(GL_UNIFORM_BUFFER, j->binding, 0);
-					++j;
-				}
-				else
-				{
-					if(i->binding==j->binding)
-						++j;
-					++i;
-				}
-			}
-		}
-
 		for(vector<BoundUniformBlock>::const_iterator i=uniform_blocks.begin(); i!=uniform_blocks.end(); ++i)
 			if(i->changed || mask==~0U)
 			{
@@ -340,9 +284,9 @@ void PipelineState::apply(unsigned mask) const
 					}
 					else
 						static_cast<const DefaultUniformBlock *>(i->block)->apply();
+
+					bound_uniform_blocks[i->binding] = 1;
 				}
-				else
-					glBindBufferBase(GL_UNIFORM_BUFFER, i->binding, 0);
 
 				i->changed = false;
 			}
@@ -402,22 +346,25 @@ void PipelineState::clear()
 			if((last_applied->enabled_clip_planes>>i)&1)
 				glDisable(GL_CLIP_PLANE0+i);
 
-		for(vector<BoundTexture>::const_iterator i=last_applied->textures.begin(); i!=last_applied->textures.end(); ++i)
-			if(i->texture && i->sampler)
+		for(unsigned i=0; i<bound_tex_targets.size(); ++i)
+			if(bound_tex_targets[i])
 			{
 				if(ARB_direct_state_access)
-					glBindTextureUnit(i->binding, 0);
+					glBindTextureUnit(i, 0);
 				else
 				{
-					glActiveTexture(GL_TEXTURE0+i->binding);
-					glBindTexture(bound_tex_targets[i->binding], 0);
-					bound_tex_targets[i->binding] = 0;
+					glActiveTexture(GL_TEXTURE0+i);
+					glBindTexture(bound_tex_targets[i], 0);
 				}
+				bound_tex_targets[i] = 0;
 			}
 
-		for(vector<BoundUniformBlock>::const_iterator i=last_applied->uniform_blocks.begin(); i!=last_applied->uniform_blocks.end(); ++i)
-			if(i->block)
-				glBindBufferBase(GL_UNIFORM_BUFFER, i->binding, 0);
+		for(unsigned i=0; i<bound_uniform_blocks.size(); ++i)
+			if(bound_uniform_blocks[i])
+			{
+				glBindBufferBase(GL_UNIFORM_BUFFER, i, 0);
+				bound_uniform_blocks[i] = 0;
+			}
 
 		glDisable(GL_DEPTH_TEST);
 		glDepthMask(true);
diff --git a/source/core/pipelinestate.h b/source/core/pipelinestate.h
index f3c30030..b9fac143 100644
--- a/source/core/pipelinestate.h
+++ b/source/core/pipelinestate.h
@@ -76,6 +76,7 @@ private:
 
 	static const PipelineState *last_applied;
 	static std::vector<int> bound_tex_targets;
+	static std::vector<char> bound_uniform_blocks;
 	static unsigned restart_index;
 
 public:
-- 
2.45.2