/// <summary>
///
/// </summary>
/// <param name="model"></param>
/// <returns></returns>
public IPickableRenderUnit ToRenderUnit(IBufferSource model)
{
// init shader program.
ShaderProgram pickProgram = this.programProvider.GetShaderProgram();
// init vertex attribute buffer objects.
VertexBuffer positionBuffer = model.GetVertexAttributeBuffer(this.positionNameInIBufferSource);
// RULE: 由于picking.vert/frag只支持vec3的position buffer，所以有此硬性规定。
if (positionBuffer == null || positionBuffer.Config != VBOConfig.Vec3)
{
throw new Exception(string.Format("Position buffer must use a type composed of 3 float as PropertyBuffer<T>'s T!"));
}
// init index buffer.
IndexBuffer indexBuffer = model.GetIndexBuffer();
// init VAO.
var pickingVAO = new VertexArrayObject(indexBuffer, pickProgram, new VertexShaderAttribute(positionBuffer, PickingShaderHelper.in_Position));
var renderUnit = new IPickableRenderUnit(pickProgram, pickingVAO, positionBuffer, this.states);
// RULE: Renderer takes uint.MaxValue, ushort.MaxValue or byte.MaxValue as PrimitiveRestartIndex. So take care this rule when designing a model's index buffer.
var ptr = indexBuffer as OneIndexBuffer;
if (ptr != null)
{
GLState glState = new PrimitiveRestartState(ptr.ElementType);
renderUnit.StateList.Add(glState);
}
return(renderUnit);
}
/// <summary>
///
/// </summary>
protected override void DoInitialize()
{
foreach (var item in this.builders)
{
RenderUnit renderUnit = item.ToRenderUnit(this.model);
this.renderUnits.Add(renderUnit);
}
{
IPickableRenderUnit renderUnit = this.pickingRenderUnitBuilder.ToRenderUnit(this.model);
if (renderUnit.VertexArrayObject.IndexBuffer is ZeroIndexBuffer)
{
this.picker = new ZeroIndexPicker(this);
}
else if (renderUnit.VertexArrayObject.IndexBuffer is OneIndexBuffer)
{
this.picker = new OneIndexPicker(this);
}
this.PickingRenderUnit = renderUnit;
}
}
