/// <summary>
///
/// </summary>
/// <param name="arg"></param>
/// <param name="lastVertexId"></param>
/// <param name="picker"></param>
/// <returns></returns>
internal override uint[] Search(PickingEventArgs arg,
uint lastVertexId, ZeroIndexPicker picker)
{
OneIndexBuffer buffer = GLBuffer.Create(IndexBufferElementType.UInt, 6, DrawMode.Lines, BufferUsage.StaticDraw);
unsafe
{
var array = (uint *)buffer.MapBuffer(MapBufferAccess.WriteOnly);
array[0] = lastVertexId - 2; array[1] = lastVertexId - 0;
array[2] = lastVertexId - 4; array[3] = lastVertexId - 2;
array[4] = lastVertexId - 0; array[5] = lastVertexId - 4;
buffer.UnmapBuffer();
}
picker.Renderer.Render4InnerPicking(arg, buffer);
uint id = ColorCodedPicking.ReadStageVertexId(arg.X, arg.Y);
buffer.Dispose();
if (id + 4 == lastVertexId)
{
return(new uint[] { id + 4, id, });
}
else
{
return(new uint[] { id - 2, id, });
}
}
/// <summary>
/// 在三角形图元中拾取指定位置的Line
/// </summary>
/// <param name="arg"></param>
/// <param name="lastVertexId">三角形图元的最后一个顶点</param>
/// <param name="picker"></param>
/// <returns></returns>
internal override uint[] Search(PickingEventArgs arg,
uint lastVertexId, ZeroIndexPicker picker)
{
// 创建临时索引
OneIndexBuffer buffer = GLBuffer.Create(IndexBufferElementType.UInt, 6, DrawMode.Lines, BufferUsage.StaticDraw);
unsafe
{
var array = (uint *)buffer.MapBuffer(MapBufferAccess.WriteOnly);
array[0] = lastVertexId - 1; array[1] = lastVertexId - 0;
array[2] = lastVertexId - 2; array[3] = lastVertexId - 1;
array[4] = lastVertexId - 0; array[5] = lastVertexId - 2;
buffer.UnmapBuffer();
}
// 用临时索引渲染此三角形图元（仅渲染此三角形图元）
picker.Renderer.Render4InnerPicking(arg, buffer);
// id是拾取到的Line的Last Vertex Id
uint id = ColorCodedPicking.ReadStageVertexId(arg.X, arg.Y);
buffer.Dispose();
// 对比临时索引，找到那个Line
if (id + 2 == lastVertexId)
{
return(new uint[] { id + 2, id, });
}
else
{
return(new uint[] { id - 1, id, });
}
}
/// <summary>
///
/// </summary>
/// <param name="arg"></param>
/// <param name="lastVertexId"></param>
/// <param name="picker"></param>
/// <returns></returns>
internal override uint[] Search(PickingEventArgs arg, uint lastVertexId, ZeroIndexPicker picker)
{
var zeroIndexBuffer = picker.Node.PickingRenderUnit.VertexArrayObject.IndexBuffer as ZeroIndexBuffer;
// when the temp index buffer could be long, it's no longer needed.
// what a great OpenGL API design!
ZeroIndexBuffer indexBuffer = ZeroIndexBuffer.Create(DrawMode.LineLoop, zeroIndexBuffer.FirstVertex, zeroIndexBuffer.RenderingVertexCount, zeroIndexBuffer.InstanceCount);
picker.Node.Render4InnerPicking(arg, indexBuffer);
uint id = ColorCodedPicking.ReadStageVertexId(arg.X, arg.Y);
indexBuffer.Dispose();
if (id == zeroIndexBuffer.FirstVertex)
{
return(new uint[] { (uint)(zeroIndexBuffer.FirstVertex + zeroIndexBuffer.RenderingVertexCount - 1), id, });
}
else
{
return(new uint[] { id - 1, id, });
}
}
/// <summary>
///
/// </summary>
/// <param name="arg"></param>
/// <param name="lastVertexId"></param>
/// <param name="picker"></param>
/// <returns></returns>
internal abstract uint[] Search(PickingEventArgs arg,
uint lastVertexId, ZeroIndexPicker picker);
