/// <summary>
/// Perform material modification in this function.
/// 获取修改后的材质
/// 默认的实现为替换材质，根据是否父物体为 Mask 组件，修改 Stencil 值，通过shader 的模板功能实现遮罩
/// </summary>
public virtual Material GetModifiedMaterial(Material baseMaterial)
{
var toUse = baseMaterial;
if (m_ShouldRecalculateStencil)
{
var rootCanvas = MaskUtilities.FindRootSortOverrideCanvas(transform);
m_StencilValue = maskable ?
MaskUtilities.GetStencilDepth(transform, rootCanvas) : 0;
m_ShouldRecalculateStencil = false;
}
// if we have a enabled Mask component then it will
// generate the mask material. This is an optimisation
// it adds some coupling between components though :(
Mask maskComponent = GetComponent <Mask>();
if (m_StencilValue > 0 &&
(maskComponent == null || !maskComponent.IsActive()))
{
var maskMat = StencilMaterial.Add(toUse,
(1 << m_StencilValue) - 1,
StencilOp.Keep,
CompareFunction.Equal,
ColorWriteMask.All,
(1 << m_StencilValue) - 1,
0);
StencilMaterial.Remove(m_MaskMaterial);
m_MaskMaterial = maskMat;
toUse = m_MaskMaterial;
}
return(toUse);
}
/// Stencil calculation time!
public virtual Material GetModifiedMaterial(Material baseMaterial)
{
if (graphic == null)
{
return(baseMaterial);
}
var rootSortCanvas = MaskUtilities.FindRootSortOverrideCanvas(transform);
var stencilDepth = MaskUtilities.GetStencilDepth(transform, rootSortCanvas);
if (stencilDepth >= 8)
{
Debug.LogError("Attempting to use a stencil mask with depth > 8", gameObject);
return(baseMaterial);
}
int desiredStencilBit = 1 << stencilDepth;
// if we are at the first level...
// we want to destroy what is there
if (desiredStencilBit == 1)
{
var maskMaterial = StencilMaterial.Add(baseMaterial, 1, StencilOp.Replace, CompareFunction.Always, m_ShowMaskGraphic ? ColorWriteMask.All : 0);
StencilMaterial.Remove(m_MaskMaterial);
m_MaskMaterial = maskMaterial;
var unmaskMaterial = StencilMaterial.Add(baseMaterial, 1, StencilOp.Zero, CompareFunction.Always, 0);
StencilMaterial.Remove(m_UnmaskMaterial);
m_UnmaskMaterial = unmaskMaterial;
graphic.canvasRenderer.popMaterialCount = 1;
graphic.canvasRenderer.SetPopMaterial(m_UnmaskMaterial, 0);
return(m_MaskMaterial);
}
//otherwise we need to be a bit smarter and set some read / write masks
var maskMaterial2 = StencilMaterial.Add(baseMaterial, desiredStencilBit | (desiredStencilBit - 1), StencilOp.Replace, CompareFunction.Equal, m_ShowMaskGraphic ? ColorWriteMask.All : 0, desiredStencilBit - 1, desiredStencilBit | (desiredStencilBit - 1));
StencilMaterial.Remove(m_MaskMaterial);
m_MaskMaterial = maskMaterial2;
graphic.canvasRenderer.hasPopInstruction = true;
var unmaskMaterial2 = StencilMaterial.Add(baseMaterial, desiredStencilBit - 1, StencilOp.Replace, CompareFunction.Equal, 0, desiredStencilBit - 1, desiredStencilBit | (desiredStencilBit - 1));
StencilMaterial.Remove(m_UnmaskMaterial);
m_UnmaskMaterial = unmaskMaterial2;
graphic.canvasRenderer.popMaterialCount = 1;
graphic.canvasRenderer.SetPopMaterial(m_UnmaskMaterial, 0);
return(m_MaskMaterial);
}