Cycles: Added Float2 attribute type.

Float2 are now a new type for attributes in Cycles. Before, the choices
for attribute storage were float and float3, the latter padded to
float4. This meant that UV maps were inflated to twice the size
necessary.

Reviewers: brecht, sergey

Reviewed By: brecht

Subscribers: #cycles

Tags: #cycles

Differential Revision: https://developer.blender.org/D4409

intern/cycles/render/nodes.cpp

@@ -3483,7 +3483,7 @@ void TextureCoordinateNode::compile(SVMCompiler& compiler)
 		}
 		else {
 			int attr = compiler.attribute(ATTR_STD_UV);
-			compiler.add_node(attr_node, attr, compiler.stack_assign(out), NODE_ATTR_FLOAT3);
+			compiler.add_node(attr_node, attr, compiler.stack_assign(out), NODE_ATTR_FLOAT2);
 		}
 	}