/// <summary>
/// Loads a COLLADA section
/// </summary>
/// <param name="reader">XML reader</param>
public override object LoadSection( XmlReader reader )
{
Hashtable sources = new Hashtable( );
MeshVertices vertices = null;
MeshPolygons polygons = null;
while ( reader.Read( ) && reader.NodeType != XmlNodeType.EndElement )
{
if ( reader.NodeType != XmlNodeType.Element )
{
continue;
}
switch ( reader.Name )
{
case "source":
{
sources[ reader.GetAttribute( "id" ) ] = new MeshSource( reader );
break;
}
case "vertices":
{
vertices = new MeshVertices( reader, sources );
break;
}
case "polygons":
{
polygons = new MeshPolygons( reader, false, false );
break;
}
case "triangles":
{
polygons = new MeshPolygons( reader, true, false );
break;
}
default:
{
ReadPastElement( reader );
break;
}
}
}
return BuildMesh( vertices, polygons );
}
/// <summary>
/// Builds an OpenGL mesh
/// </summary>
private object BuildMesh( MeshVertices vertices, MeshPolygons polygons )
{
OpenGlMesh mesh = new OpenGlMesh( );
// Set up the index buffer in the mesh
if ( polygons.StoredAsTriangles )
{
int[] indexBuffer = new int[ polygons.Polygons.Count * 3 ];
int curIndex = 0;
foreach ( MeshPolygon curPoly in polygons.Polygons )
{
indexBuffer[ curIndex++ ] = curPoly.Indices[ 0 ];
indexBuffer[ curIndex++ ] = curPoly.Indices[ 1 ];
indexBuffer[ curIndex++ ] = curPoly.Indices[ 2 ];
}
mesh.CreateGroups( 1 );
mesh.SetGroup( 0, new OpenGlIndexedGroup( Gl.GL_TRIANGLES, indexBuffer ) );
}
else
{
throw new ApplicationException( "sorry, non-triange index buffers not implemented yet" );
}
mesh.CreateVertexBuffers( vertices.Sources.Count );
int vboIndex = 0;
foreach ( MeshTaggedSource curSource in vertices.Sources )
{
// Convert the source semantic to an opengl client state
// Swap y and z elements
// TODO: Should be a resource flag, at the very least
bool swapYz = false;
int clientState = 0;
switch ( curSource.Semantic )
{
case "POSITION": clientState = Gl.GL_VERTEX_ARRAY; swapYz = true; break;
case "NORMAL": clientState = Gl.GL_NORMAL_ARRAY; swapYz = true; break;
case "COLOR": clientState = Gl.GL_COLOR_ARRAY; break;
default:
throw new ApplicationException( string.Format( "Unknown mesh semantic \"{0}\"", curSource.Semantic ) );
}
// Store the stride (note, for GL this has a slightly different meaning, I think. TODO: Check COLLADA spec. to make sure)
int numObjects = curSource.Source.Data.Count / curSource.Source.Stride;
short stride = 0;
short numElements = ( short )curSource.Source.Stride;
Type dataType = curSource.Source.DataType;
switch ( Type.GetTypeCode( dataType ) )
{
case TypeCode.Single:
{
// HACK: Swap y and z coordinates - in blender (the 3d editor I'm currently using), z is up, in the engine, y is up.
float[] bufferData = ( float[] )curSource.Source.Data.ToArray( dataType );
if ( swapYz )
{
for ( int index = 0; index < bufferData.Length; index += 3 )
{
float tmp = bufferData[ index + 1 ];
bufferData[ index + 1 ] = bufferData[ index + 2 ];
bufferData[ index + 2 ] = tmp;
}
}
mesh.SetVertexBuffer( vboIndex, new OpenGlVertexBuffer( numObjects, 0, clientState, stride, numElements, Gl.GL_STATIC_DRAW_ARB, bufferData ) );
break;
}
case TypeCode.Int32:
{
int[] bufferData = ( int[] )curSource.Source.Data.ToArray( dataType );
mesh.SetVertexBuffer( vboIndex, new OpenGlVertexBuffer( numObjects, 0, clientState, stride, numElements, Gl.GL_STATIC_DRAW_ARB, bufferData ) );
break;
}
case TypeCode.Byte:
{
byte[] bufferData = ( byte[] )curSource.Source.Data.ToArray( dataType );
mesh.SetVertexBuffer( vboIndex, new OpenGlVertexBuffer( numObjects, 0, clientState, stride, numElements, Gl.GL_STATIC_DRAW_ARB, bufferData ) );
break;
}
default:
{
throw new ApplicationException( string.Format( "Unhandled vertex source type \"{0}\"", curSource.Source.DataType.Name ) );
}
}
++vboIndex;
}
return mesh;
}
