Terrain Materials

Terrain components require materials whose shaders understand the terrain's vertex format. The engine ships sample shader implementations that can be used directly or as a reference for custom shaders. The necessary setup code is provided in headers that can be easily reused in custom shaders.

Sample Shaders

Two ready-to-use sample shaders are provided:

Shaders/Terrain/Rendering/HeightfieldTerrainMaterial.ezShader — for terrain patches.
Shaders/Terrain/Rendering/VoxelMeshMaterial.ezShader — for terrain volumes.

Example material assets that use these shaders can be found in the Testing Chambers sample project under Data/Samples/Testing Chambers/Materials/.

Texture Setup

Both sample shaders use three texture arrays (type Texture2DArray):

LayerBaseTexture — diffuse/albedo color.
LayerNormalTexture — normal maps.
LayerRoughnessTexture — roughness, read from the R channel. The sample shaders take metallic from a material-wide MetallicValue constant instead of a texture channel, and disable ambient occlusion on terrain geometry entirely.

The sample material supports up to 8 layers and there is a mapping to reuse the same texture layer across different material layers. The shader uses different textures to project onto the ground and walls. This is just one way to do this, when you write your own terrain shaders, you can use entirely different methods to organize your data and you can support much more layers, as well.

Writing a Custom Heightfield Shader

The engine exposes the heightfield's vertex data through include-able header files. A custom heightfield shader must do the following:

Vertex shader:

Before including any material interpolator header, declare the custom interpolator that carries the upper two blend weights to the pixel shader:
```
#define CUSTOM_INTERPOLATOR float2 MatWeightsHi : TEXCOORD2;
```
Include <Shaders/Terrain/Rendering/HeightfieldTerrainVS.h>. This provides the FillHeightfieldTerrainVertexOutput(uint vertexID) function and declares the GPU buffers for heights, normals, cell materials, and per-vertex blend weights.
Call FillHeightfieldTerrainVertexOutput(input.VertexID) from the main vertex shader function and return its result.

The vertex output carries:

TexCoord0.x/y — blend weights w0 and w1 for the top two material layers.
MatWeightsHi.x/y — blend weights w2 and w3 for the third and fourth material layers.
DataOffsets.y — four packed 8-bit cell material indices (mat0 in bits 0–7, mat1 in bits 8–15, mat2 in bits 16–23, mat3 in bits 24–31).

A fifth implicit weight for the fallback material slot (given by the FallbackMaterialSlot push constant) is reconstructed as max(0, 1 - w0 - w1 - w2 - w3).

Pixel shader:

Include <Shaders/Terrain/Rendering/TerrainLayerSampling.h> after MaterialPixelShader.h. This provides:

TriplanarWeights(float3 worldNormal) — computes blend weights for triplanar projection.
TriplanarSampleColorArray(tex, samp, worldPos, worldNormal, weights, scale, matIndex) — samples one layer from a color texture array using triplanar projection.
TriplanarSampleNormalArray(tex, samp, worldPos, worldNormal, weights, scale, matIndex) — same for normal map arrays; returns a world-space normal.

Writing a Custom Voxel Shader

Vertex shader:

Include <Shaders/Terrain/Rendering/VoxelTerrainVS.h> in the vertex shader section. This provides FillVoxelTerrainVertexOutput(uint vertexID) and declares the GPU vertex and index buffers.