Mesh Rendering - Practical Rendering and Computation with Direct3D 11 - page 405

[domain("tri")]
DS_OUTPUT DSMAIN( const OutputPatch<HS_POINT_OUTPUT, 3> TriPatch,
float3 Coords : SVOomainLocation,
HS_PATCH_OUTPUT input )

{

DS_OUTPUT output;

// Interpolate world space position
float4 vWorldPos = Coords.x * TriPatch[6].position
+ Coords.y * TriPatch[l].position
+ Coords.z * TriPatch[2] .position;

// Calculate the interpolated normal vector
output.normal = Coords.x * TriPatch [0] .normal
+ Coords.y * TriPatch[l].normal
+ Coords.z * TriPatch[2].normal;

// Normalize the vector length for use in displacement
output.normal = normalize( output.normal );

// Interpolate the texture coordinates
output.tex = Coords.x * TriPatch[0] .tex
+ Coords.y * TriPatch[l] .tex
+ Coords.z * TriPatch[2].tex;

// Calculate the interpolated world space light vector.
output.light = Coords.x * TriPatch[0].light
+ Coords.y * TriPatch[l].light
+ Coords.z * TriPatch[2].light;

// Calculate MIP level to fetch normal from
float fHeightMapMIPLevel =
clamp( ( distance( vWorldPos.xyz, vEye.xyz ) - 100.0f ) / 100.0f,
0.0f,
3.0f);

// Sample the height map to know how much to displace the surface by
float4 texHeight =
HeightTexture.SampleLevel( LinearSampler, output.tex,
fHeightMapMIPLevel );

// Perform the displacement. The ' fScale' parameter determines the maximum
// world space offset that can be applied to the surface. The displacement
// is performed along the interpolated vertex normal vector.
const float fScale = 0.5f;
vWorldPos . xyz = vWorldPos . xyz + output.normal * texHeight.r * fScale;

// Transform world position with viewprojection matrix
output.position = mul( vWorldPos, ViewProjMatrix );

return output;

}

Listing 8.5. The domain shader program for implementing displacement mapping.