From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 4 Apr 2011 16:44:40 +0000 (+0000)
Subject: Add a method to get the offset of a single component of a VertexFormat
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=c254bc3ed8df9c4113c975bdd119f127d8360f86

Add a method to get the offset of a single component of a VertexFormat
---

diff --git a/source/vertexformat.cpp b/source/vertexformat.cpp
index 2b18178b..adb33c2a 100644
--- a/source/vertexformat.cpp
+++ b/source/vertexformat.cpp
@@ -64,6 +64,30 @@ unsigned VertexFormat::stride() const
 	return s;
 }
 
+int VertexFormat::offset(VertexComponent comp, unsigned index) const
+{
+	if((comp<TEXCOORD1 && index>0) || (comp<ATTRIB1 && index>=8) || index>=53)
+		throw InvalidParameterValue("Vertex component index out of range");
+
+	unsigned type = (comp>>2)+index;
+	unsigned size = comp&3;
+	unsigned offs = 0;
+	for(const unsigned char *i=begin(); i!=end(); ++i)
+	{
+		if((*i>>2)==type)
+		{
+			if((*i&3)>=size)
+				return offs;
+			else
+				return -1;
+		}
+		else
+			offs += (*i&3)+1;
+	}
+
+	return -1;
+}
+
 VertexFormat operator,(const VertexFormat &f, VertexComponent c)
 {
 	VertexFormat r = f;
diff --git a/source/vertexformat.h b/source/vertexformat.h
index 53562ef9..27033200 100644
--- a/source/vertexformat.h
+++ b/source/vertexformat.h
@@ -46,6 +46,7 @@ struct VertexFormat
 	const unsigned char *begin() const { return data ? data+1 : 0; }
 	const unsigned char *end() const { return data ? data+1+data[0] : 0; }
 	unsigned stride() const;
+	int offset(VertexComponent, unsigned = 0) const;
 };
 
 VertexFormat operator,(const VertexFormat &f, VertexComponent c);