NGUI Panel Soft Clip原理分析

    void CreateMaterial ()
	｛
		mTextureClip = false;
		mLegacyShader = false;
		mClipCount = panel.clipCount;
		string shaderName = (mShader != null) ? mShader.name :
			((mMaterial != null) ? mMaterial.shader.name : "Unlit/Transparent Colored");
		// Figure out the normal shader's name
		shaderName = shaderName.Replace("GUI/Text Shader", "Unlit/Text");
		if (shaderName.Length > 2)
		｛
			if (shaderName[shaderName.Length - 2] == ' ')
			｛
				int index = shaderName[shaderName.Length - 1];
				if (index > '0' && index <= '9') shaderName = shaderName.Substring(0, shaderName.Length - 2);
			｝
		｝
		shaderName = shaderName.Replace(TEXTURE_CLIP, "");
        var newShader = shader;
        //如果是Mask裁剪，就直接寻找 Unlit/Transparent Colored(TextureClip)这样 或者 Unlit/Text(TextureClip)这样的shader
        if (panel.clipping == Clipping.TextureMask)
		｛
			mTextureClip = true;
            newShader = Shader.Find(shaderName + TEXTURE_CLIP);
		｝
		else if (mClipCount != 0)       //如果父节点有多个裁剪panel 就设置成Soft Clip的形式
		｛
            //寻找的Shader格式为  Unlit/Transparent Colored 1 或者  Unlit/Transparent Colored 2 这样的 ，后缀就是有多少层，最大ngui写到了3，一般够用了
            var shaderPath = shaderName + " " + mClipCount;
            newShader = Shader.Find(shaderPath);
		｝
        else newShader = Shader.Find(shaderName);
		// Always fallback to the default shader 如果找不到 就用默认的shader 一般设置成这个shader，就是达不到你需要的效果了
        if (newShader == null) newShader = Shader.Find("Unlit/Transparent Colored");
		if (mMaterial != null)
		｛
			mDynamicMat = new Material(mMaterial);
			mDynamicMat.name = "[NGUI] " + mMaterial.name;
			mDynamicMat.hideFlags = HideFlags.DontSave | HideFlags.NotEditable;
			mDynamicMat.CopyPropertiesFromMaterial(mMaterial);      //这里会把之前的材质的所有属性全部复制到新的材质上（贴图啊什么的 很方便啊）
#if !UNITY_FLASH
			string[] keywords = mMaterial.shaderKeywords;
			for (int i = 0; i < keywords.Length; ++i)
				mDynamicMat.EnableKeyword(keywords[i]);
#endif
			// If there is a valid shader, assign it to the custom material
            if (newShader != null)
			｛
                mDynamicMat.shader = newShader;
			｝
			else if (mClipCount != 0)
			｛
				Debug.LogError(shaderName + " shader doesn't have a clipped shader version for " + mClipCount + " clip regions");
			｝
		｝
		else
		｛
            mDynamicMat = new Material(newShader);
            mDynamicMat.name = "[NGUI] " + newShader.name;
			mDynamicMat.hideFlags = HideFlags.DontSave | HideFlags.NotEditable;
		｝
	｝

	void OnWillRenderObject ()
	｛
		UpdateMaterials();
		if (onRender != null) onRender(mDynamicMat ?? mMaterial);
		if (mDynamicMat == null || mClipCount == 0) return;
		if (mTextureClip)
		｛
			Vector4 cr = panel.drawCallClipRange;
			Vector2 soft = panel.clipSoftness;
			Vector2 sharpness = new Vector2(1000.0f, 1000.0f);
			if (soft.x > 0f) sharpness.x = cr.z / soft.x;
			if (soft.y > 0f) sharpness.y = cr.w / soft.y;
			mDynamicMat.SetVector(ClipRange[0], new Vector4(-cr.x / cr.z, -cr.y / cr.w, 1f / cr.z, 1f / cr.w));
			mDynamicMat.SetTexture("_ClipTex", clipTexture);
		｝
		else if (!mLegacyShader)
		｛
			UIPanel currentPanel = panel;
			for (int i = 0; currentPanel != null; )
			｛
				if (currentPanel.hasClipping)
				｛
					float angle = 0f;
					Vector4 cr = currentPanel.drawCallClipRange;
					// Clipping regions past the first one need additional math
					if (currentPanel != panel)
					｛
						Vector3 pos = currentPanel.cachedTransform.InverseTransformPoint(panel.cachedTransform.position);
						cr.x -= pos.x;
						cr.y -= pos.y;
						Vector3 v0 = panel.cachedTransform.rotation.eulerAngles;
						Vector3 v1 = currentPanel.cachedTransform.rotation.eulerAngles;
						Vector3 diff = v1 - v0;
						diff.x = NGUIMath.WrapAngle(diff.x);
						diff.y = NGUIMath.WrapAngle(diff.y);
						diff.z = NGUIMath.WrapAngle(diff.z);
						if (Mathf.Abs(diff.x) > 0.001f || Mathf.Abs(diff.y) > 0.001f)
							Debug.LogWarning("Panel can only be clipped properly if X and Y rotation is left at 0", panel);
						angle = diff.z;
					｝
					// Pass the clipping parameters to the shader
					SetClipping(i++, cr, currentPanel.clipSoftness, angle);
				｝
				currentPanel = currentPanel.parentPanel;
			｝
		｝
		else // Legacy functionality
		｛
			Vector2 soft = panel.clipSoftness;
			Vector4 cr = panel.drawCallClipRange;
			Vector2 v0 = new Vector2(-cr.x / cr.z, -cr.y / cr.w);
			Vector2 v1 = new Vector2(1f / cr.z, 1f / cr.w);
			Vector2 sharpness = new Vector2(1000.0f, 1000.0f);
			if (soft.x > 0f) sharpness.x = cr.z / soft.x;
			if (soft.y > 0f) sharpness.y = cr.w / soft.y;
			mDynamicMat.mainTextureOffset = v0;
			mDynamicMat.mainTextureScale = v1;
			mDynamicMat.SetVector("_ClipSharpness", sharpness);
		｝
	｝