Merge pull request #1272 from proberts-cinesite/IECoreGL-accessors

IECoreGL Buffer/Primitive accessors

Author: danieldresser-ie

include/IECoreGL/Buffer.h

@@ -62,6 +62,12 @@ class IECOREGL_API Buffer : public IECore::RunTimeTyped
 		/// Deletes the buffer with glDeleteBuffers().
 		~Buffer() override;
 
+		/// Returns the GL handle for the buffer. Note that this is
+		/// owned by the Buffer class and will be destroyed in the
+		/// destructor - you must therefore not call glDeleteBuffers()
+		/// yourself.
+		GLuint buffer() const;
+
 		/// Returns the size of the buffer in bytes.
 		size_t size() const;
 

include/IECoreGL/Primitive.h

@@ -37,6 +37,7 @@
 
 #include "IECoreGL/Export.h"
 #include "IECoreGL/GL.h"
+#include "IECoreGL/Buffer.h"
 #include "IECoreGL/Renderable.h"
 #include "IECoreGL/Shader.h"
 #include "IECoreGL/TypedStateComponent.h"
@@ -165,6 +166,12 @@ class IECOREGL_API Primitive : public Renderable
 		IE_CORE_DECLAREPTR( TransparencySort );
 		//@}
 
+		/// Call to retrieve the buffer for a previously registered vertex attribute.
+		ConstBufferPtr getVertexBuffer( const std::string &name ) const;
+
+		/// Call to determine the number of vertices in each registered vertex attribute.
+		size_t getVertexCount() const;
+
 	protected :
 
 		/// Called by derived classes to register a uniform attribute. There are no type or length checks on this call.

src/IECoreGL/Buffer.cpp

@@ -94,6 +94,11 @@ Buffer::~Buffer()
 	glDeleteBuffers( 1, &m_buffer );
 }
 
+GLuint Buffer::buffer() const
+{
+	return m_buffer;
+}
+
 size_t Buffer::size() const
 {
 	ScopedBinding binding( *this, GL_ARRAY_BUFFER );

src/IECoreGL/Primitive.cpp

@@ -153,6 +153,8 @@ const Shader::Setup *flatConstantShaderSetup( State *state, bool forIDRender )
 	return shaderSetup.get();
 }
 
+const std::string g_P( "P" );
+
 } // namespace
 
 //////////////////////////////////////////////////////////////////////////
@@ -380,6 +382,28 @@ void Primitive::addVertexAttribute( const std::string &name, IECore::ConstDataPt
 	m_vertexAttributes[name] = data->copy();
 }
 
+ConstBufferPtr Primitive::getVertexBuffer( const std::string &name ) const
+{
+	const AttributeMap::const_iterator it = m_vertexAttributes.find( name );
+	return ( it != m_vertexAttributes.end() )
+		? IECore::runTimeCast< const Buffer >( CachedConverter::defaultCachedConverter()->convert( it->second.get() ) )
+		: ConstBufferPtr();
+}
+
+size_t Primitive::getVertexCount() const
+{
+	// NOTE : It would perhaps be better if the vertex count was stored as a member variable, then we could
+	//        check the size of each registered vertex attribute as it is added. Derived classes would need
+	//        to set this value perhaps as an argument to the constructor. However that would break ABI so for
+	//        now determine the vertex count by inspecting the size of the "P" attribute which ALL primitives
+	//        should have registered.
+
+	const AttributeMap::const_iterator it = m_vertexAttributes.find( g_P );
+	return ( ( it != m_vertexAttributes.end() ) && ( IECore::runTimeCast< const IECore::V3fVectorData >( it->second ) ) )
+		? static_cast< size_t >( IECore::assertedStaticCast< const IECore::V3fVectorData >( it->second )->readable().size() )
+		: static_cast< size_t >( 0 );
+}
+
 bool Primitive::depthSortRequested( const State * state ) const
 {
 	return state->get<Primitive::TransparencySort>()->value() &&