87 lines
3.1 KiB
Markdown
87 lines
3.1 KiB
Markdown
# Custom Terrain Tool shaders
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If you don't want to use the built-in painting Material, you need to create your own shader. You can then use that shader to create a Material, and use that Material instead to modify Terrain Texture data.
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Here is an example Terrain Tool shader.
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```
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Shader "TerrainTool/CustomTerrainTool"
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{
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Properties { _MainTex ("Texture", any) = "" {} }
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SubShader
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{
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ZTest Always Cull Off ZWrite Off
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HLSLINCLUDE
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#include "UnityCG.cginc"
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#include "Packages/com.unity.terrain-tools/Shaders/TerrainTools.hlsl"
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sampler2D _MainTex;
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float4 _MainTex_TexelSize; // 1/width, 1/height, width, height
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sampler2D _BrushTex;
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float4 _BrushParams;
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#define BRUSH_STRENGTH (_BrushParams[0])
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#define BRUSH_TARGETHEIGHT (_BrushParams[1])
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#define kMaxHeight (32766.0f/65535.0f)
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struct appdata_t
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{
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float4 vertex : POSITION;
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float2 pcUV : TEXCOORD0;
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};
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struct v2f
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{
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float4 vertex : SV_POSITION;
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float2 pcUV : TEXCOORD0;
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};
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v2f vert(appdata_t v)
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{
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v2f o;
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o.vertex = UnityObjectToClipPos(v.vertex);
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o.pcUV = v.pcUV;
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return o;
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}
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ENDHLSL
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Pass
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{
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Name "CustomTerrainTool"
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HLSLPROGRAM
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#pragma vertex vert
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#pragma fragment frag
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float4 frag(v2f i) : SV_Target
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{
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float2 brushUV = PaintContextUVToBrushUV(i.pcUV);
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// out of bounds multiplier
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float oob = all(saturate(brushUV) == brushUV) ? 1.0f : 0.0f;
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// Sample the MainTex, which should be a region of the source Heightmap texture, to get the current height value at the provided UV
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// UnpackHeightmap is necessary here because it unpacks the height value from R and G channels if the current platform/graphics device does not support R16_UNorm texture formats. If R16_UNorm formats are supported, UnpackHeightmap just reads from the R channel.
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float height = UnpackHeightmap(tex2D(_MainTex, i.pcUV));
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// Calculate the influence from the brush mask at this fragment
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float brushShape = oob * UnpackHeightmap(tex2D(_BrushTex, brushUV));
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// Calculate the new height value
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height = height + BRUSH_STRENGTH * brushShape;
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// Store the new height into the destination RenderTexture. Clamp between 0.0f and 0.5f because the Heightmap itself is signed but is treated as an unsigned texture when rendering the Terrain
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// PackHeightmap is necessary here because it packs the height value into R and G channels if the current platform/graphics device does not support R16_UNorm texture formats. If R16_UNorm formats are supported, PackHeightmap just writes to the R channel.
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return PackHeightmap(clamp(height, 0, kMaxHeight));
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}
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ENDHLSL
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}
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}
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}
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```
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