Lightmapped 4WayBlend

It is a shader that blends the vertices of a displacement surface between four different materials. It handles four at once by using mirrored sets of parameters with "2", "3", or "4" in their name.
The first 2 textures can have bumpmaps like . If you want to use an envmap and have masking then you should use the alpha channels of the base textures and . This shader does not support in . You can use an texture, but you'll have to hand paint it to match what you want on the blended result.
Being a replacement of the older shader, it was introduced to for the map cs_insertion.
==Example==
 Lightmapped_4WayBlend
 {
 "$basetexture" "brick_a"
 "$bumpmap" "brick_a_normal"
 "$texture1_lumstart" "0.0"
 "$texture1_lumend" "0.5"
 "$basetexture2" "brick_a"
 "$ssbump" "1"
 "$bumpmap2" "brick_a_normal"
 "$basenormalmap2"		"nature/bnc_dirt_rocky_large_001_norm" //Only Black Mesa
 "$surfaceprop" "concrete"
 "$texture2_lumstart" "0.0"
 "$texture2_lumend" "0.5"
 "$texture2_blendmode" "0"
 "$texture2_blendstart" "0.8"
 "$texture2_blendend" "0.9"
 "$texture2_uvscale" "[1.0 1.0]"
 "$texture2_bumpblendfactor" "0.7"
 "$basetexture3" "brick_a_bottom_grime"
 "$texture3_blendmode" "0"
 "$texture3_uvscale" "[2.0 2.0]"
 "$texture3_lumstart" "0.0"
 "$texture3_lumend" "0.05"
 "$texture3_blendstart" "0.8"
 "$texture3_blendend" "1.0"
 "$texture3_bumpblendfactor" "0.7"
 "$basetexture4" "brick_a_top_grime"
 "$texture4_blendmode" "0"
 "$texture4_uvscale" "[2.0 2.0]"
 "$texture4_lumstart" "0.0"
 "$texture4_lumend" "0.2"
 "$texture4_blendstart" "0.90"
 "$texture4_blendend" "0.99"
 "$texture4_bumpblendfactor" "0.3"
 "$detail" "detail\noise_detail_01"
 "$detailscale" "[ 32 32 ]"
 "$detailblendfactor" "0.7"
 "$detailblendfactor2" "0.4"
 "$detailblendfactor3" "0.2"
 "$detailblendfactor4" "0.2"
 "$lumblendfactor2" "0.5"
 "$lumblendfactor3" "0.7"
 "$lumblendfactor4" "0.4"
 }
== Controlling Blending ==
The pattern of the blend is defined by Hammer's sculpt window blend tool (shown in the picture on the right). The texture preview in Hammer requires you to set up additional VMT files for each texture to show up in the dialog. Those are not used by the shader itself. The Alpha Blend and Color Blend features of this dialog are disabled when using 4WayBlend, they are only used by the Multiblend material.
The blend can be tuned between being a linear gradient and a more realistic look using the luminance of each basetexture adjusted by parameters. This is done using some simple math in the shader, and avoids requiring extra textures.
			
== Luminance Adjust ==
The lumstart and lumend parameters adjust the luminance value into a usable range with a smoothstep.
You can think of this as adjusting the contrast of the luminance. In general, you need more contrast to get a more interesting blend.
		
== Luminance Blending ==
When blending a given layer, you can choose between using the luminance of that layer or the inverse of blended luminance of the layers below it. This is done with the lumblendfactor parameters. 
		
== Vertex Blend Modulate ==
The resulting luminance is used to modulate the vertex blend value with this formula:
The vertexblend is what you paint using the blend tool in hammer.
	
== Blend Adjust ==
Finally, the result of that formula is adjusted by another smoothstep with the blendstart and blendend parameters.
You can think of this as adjusting the sharpness of the blend.
	
== Parameters ==
Most of these parameters have counterparts that can be applied to the first, second, third or fourth layers of a material. For brevity's sake, this will be indicated by 1 to 4 where applicable. Note that a lack of 1 means that, if intended for use with the first layer, there should simply be no number in that place.
== See also ==
* 
* 
* 
*Creating and Using 4way Blend in 3ds Max
* 
*