From faa3d2353c58b48ef5169cf68c796937e2a9472a Mon Sep 17 00:00:00 2001
From: davidsminor <davidm@image-engine.com>
Date: Tue, 3 Dec 2013 11:56:30 -0800
Subject: [PATCH] Added IECoreGL::Selector::push/popIDShader()

ID shaders weren't being reverted correctly in certain situations involving ribbon curves, so Selector::loadIDShader() has been deprecated and replaced by Selector::pushIDShader(), which can be reverted using Selector::popIDShader()
---
 include/IECoreGL/Selector.h |  6 +++++
 src/IECoreGL/Selector.cpp   | 48 +++++++++++++++++++++++++++----------
 src/IECoreGL/Shader.cpp     |  9 ++++++-
 3 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/include/IECoreGL/Selector.h b/include/IECoreGL/Selector.h
index 7fcab22adb..1438bb8487 100644
--- a/include/IECoreGL/Selector.h
+++ b/include/IECoreGL/Selector.h
@@ -110,6 +110,12 @@ class Selector : boost::noncopyable
 		/// Typically one is set up automatically in baseState(), but
 		/// if rendering must be performed with an alternative shader
 		/// then it may be passed via this function.
+		void pushIDShader( const IECoreGL::Shader *idShader );
+		
+		/// Revert to previous ID shader:
+		void popIDShader();
+		
+		/// Deprecated: calls pushIDShader
 		void loadIDShader( const IECoreGL::Shader *idShader );
 		
 		/// Returns the currently active Selector - this may be used
diff --git a/src/IECoreGL/Selector.cpp b/src/IECoreGL/Selector.cpp
index 1ca59240ae..0f0df0874b 100644
--- a/src/IECoreGL/Selector.cpp
+++ b/src/IECoreGL/Selector.cpp
@@ -189,7 +189,29 @@ class Selector::Implementation : public IECore::RefCounted
 			return m_baseState;
 		}
 
-		void loadIDShader( const IECoreGL::Shader *shader )
+		void pushIDShader( const IECoreGL::Shader *shader )
+		{
+			bindIDShader( shader );
+			m_IDShaderStack.push( shader );
+		}
+		
+		void popIDShader()
+		{
+			m_IDShaderStack.pop();
+			if( m_IDShaderStack.size() )
+			{
+				bindIDShader( m_IDShaderStack.top() );
+			}
+		}
+
+		static Selector *currentSelector()
+		{
+			return g_currentSelector;
+		}
+
+	private :
+		
+		void bindIDShader( const IECoreGL::Shader *shader )
 		{
 			if( shader == m_currentIDShader )
 			{
@@ -214,7 +236,7 @@ class Selector::Implementation : public IECore::RefCounted
 			
 			m_currentIDShader = shader;
 			glUseProgram( m_currentIDShader->program() );
-					
+			
 			std::vector<GLenum> buffers;
 			buffers.resize( fragDataLocation + 1, GL_NONE );
 			buffers[buffers.size()-1] = GL_COLOR_ATTACHMENT0;
@@ -222,14 +244,7 @@ class Selector::Implementation : public IECore::RefCounted
 			
 			loadNameIDRender( m_currentName );
 		}
-
-		static Selector *currentSelector()
-		{
-			return g_currentSelector;
-		}
-
-	private :
-
+		
 		Mode m_mode;
 		std::vector<HitRecord> &m_hits;
 		StatePtr m_baseState;
@@ -285,6 +300,7 @@ class Selector::Implementation : public IECore::RefCounted
 		boost::shared_ptr<FrameBuffer::ScopedBinding> m_frameBufferBinding;
 		GLint m_prevProgram;
 		ConstShaderPtr m_currentIDShader;
+		std::stack<ConstShaderPtr> m_IDShaderStack;
 		GLint m_prevViewport[4];
 		GLint m_nameUniformLocation;
 		
@@ -346,7 +362,7 @@ class Selector::Implementation : public IECore::RefCounted
 			}
 			
 			glGetIntegerv( GL_CURRENT_PROGRAM, &m_prevProgram );
-			loadIDShader( m_baseState->get<ShaderStateComponent>()->shaderSetup()->shader() );	
+			pushIDShader( m_baseState->get<ShaderStateComponent>()->shaderSetup()->shader() );	
 		}
 
 		void loadNameIDRender( GLuint name )
@@ -484,7 +500,15 @@ State *Selector::baseState()
 
 void Selector::loadIDShader( const IECoreGL::Shader *idShader )
 {
-	m_implementation->loadIDShader( idShader );
+	m_implementation->pushIDShader( idShader );
+}
+void Selector::pushIDShader( const IECoreGL::Shader *idShader )
+{
+	m_implementation->pushIDShader( idShader );
+}
+void Selector::popIDShader()
+{
+	m_implementation->popIDShader();
 }
 
 Selector *Selector::currentSelector()
diff --git a/src/IECoreGL/Shader.cpp b/src/IECoreGL/Shader.cpp
index 4ad7c10eeb..c6701d7e6f 100644
--- a/src/IECoreGL/Shader.cpp
+++ b/src/IECoreGL/Shader.cpp
@@ -880,7 +880,7 @@ Shader::Setup::ScopedBinding::ScopedBinding( const Setup &setup )
 	{
 		if( currentSelector->mode() == Selector::IDRender )
 		{
-			currentSelector->loadIDShader( m_setup.shader() );
+			currentSelector->pushIDShader( m_setup.shader() );
 		}	
 	}
 }
@@ -894,6 +894,13 @@ Shader::Setup::ScopedBinding::~ScopedBinding()
 	}
 	
 	glUseProgram( m_previousProgram );
+	if( Selector *currentSelector = Selector::currentSelector() )
+	{
+		if( currentSelector->mode() == Selector::IDRender )
+		{
+			currentSelector->popIDShader();
+		}	
+	}
 }
 
 ///////////////////////////////////////////////////////////////////////////////