/// <summary>
/// Get the primitive of <paramref name="element"/> according to vertex's id.
/// <para>Returns <code>null</code> if <paramref name="element"/> is null or <paramref name="stageVertexID"/> is not in the range of this <paramref name="element"/>.</para>
/// <para>Note: the <paramref name="stageVertexID"/> Refers to the last vertex that constructs the primitive. And it's unique in scene's all elements.</para>
/// <para>Note: The result's positions property is not set up as there will be different kinds of storage mode for positions(float[], IntPtr, etc). You have to initialize the positions property and fill correct position information afterwards.</para>
/// </summary>
/// <typeparam name="T">Sub type of <see cref="IPickedGeometry"/></typeparam>
/// <param name="element">the scene's element that contains the primitive.</param>
/// <param name="mode">specifies what type of primitive it is.</param>
/// <param name="stageVertexID">Refers to the last vertex that constructs the primitive. And it's unique in scene's all elements.</param>
/// <returns></returns>
public static T TryPick <T>(
this IColorCodedPicking element, Enumerations.BeginMode mode, uint stageVertexID)
where T : IPickedGeometry, new()
{
T pickedGeometry = default(T);
if (element != null)
{
uint lastVertexID;
if (element.GetLastVertexIDOfPickedGeometry(stageVertexID, out lastVertexID))
{
pickedGeometry = new T();
pickedGeometry.GeometryType = mode.ToGeometryType();
pickedGeometry.StageVertexID = stageVertexID;
pickedGeometry.From = element;
}
}
return(pickedGeometry);
}
/// <summary>
/// Get the primitive of <paramref name="element"/> according to vertex's id.
/// <para>Returns <code>null</code> if <paramref name="element"/> is null or <paramref name="stageVertexID"/> does not belong to any of this <paramref name="element"/>'s vertices.</para>
/// <para>Note: the <paramref name="stageVertexID"/> refers to the last vertex that constructs the primitive. And it's unique in scene's all elements.</para>
/// </summary>
/// <typeparam name="T">Subclass of <see cref="IPickedGeometry"/></typeparam>
/// <param name="element">the scene's element that contains the primitive.</param>
/// <param name="mode">specifies what type of primitive it is.</param>
/// <param name="stageVertexID">Refers to the last vertex that constructs the primitive. And it's unique in scene's all elements.</param>
/// <param name="positions">element's vertices' position array.</param>
/// <returns></returns>
public static T TryPick <T>(
this IColorCodedPicking element, Enumerations.BeginMode mode, uint stageVertexID, float[] positions)
where T : IPickedGeometry, new()
{
if (positions == null)
{
throw new ArgumentNullException("positions");
}
T pickedGeometry = element.TryPick <T>(mode, stageVertexID);
// Fill primitive's positions and colors. This maybe changes much more than lines above in second dev.
if (pickedGeometry != null)
{
uint lastVertexID;
if (element.GetLastVertexIDOfPickedGeometry(stageVertexID, out lastVertexID))
{
int vertexCount = pickedGeometry.GeometryType.GetVertexCount();
if (vertexCount == -1)
{
vertexCount = positions.Length / 3;
}
float[] geometryPositions = new float[vertexCount * 3];
uint i = lastVertexID * 3 + 2;
for (int j = (geometryPositions.Length - 1); j >= 0; i--, j--)
{
if (i == uint.MaxValue)// This is when mode is GL_LINE_LOOP.
{
i = (uint)positions.Length - 1;
}
geometryPositions[j] = positions[i];
}
pickedGeometry.positions = geometryPositions;
}
}
return(pickedGeometry);
}
