Multithreaded Paraboloid Mapping - Practical Rendering and Computation with Direct3D 11 - page 588

OUT.z_value = OUT.position.z ;

II Store the distance to the vertex for use in the depth buffer.
OUT.position.z = L / 500 ;

II Set w to 1 since we aren't doing any perspective distortion.
OUT.position.w = 1;

II Find the world space position of the vertex.
float4 WorldPos = mul( float4( IN.position, 1 ), WorldMatrix );

// Find world space normal and eye vectors.
OUT.normal

= normalize( mul( IN.normal, (float3x3)WorldMatrix ) );

OUT.eye = normalize( WorldPos.xyz - ViewPosition.xyz );

return OUT;

}

Listing 13.6. The vertex shader for rendering a reflective object into another object's paraboloid map.

The geometry shader is also a combination of the previous methods. The parabo-
loid projection calculations are performed (including the render target selection and vertex
winding modification), then the world-space vectors are passed to the pixel shader. This
geometry shader uses the same instancing technique we have seen previously to fill both
paraboloid maps.

[maxvertexcount(3)]
[instance(2)]
void GSMAIN( triangle GS_INPUT input[3],
uint id : SV_GSInstanceID,
inout TriangleStream<PS_INPUT> OutputStream )

{

PS_INPUT output;

// Initialize the vertex order and the direction of the paraboloid.
uint3 order = uint3( 0, 1, 2 );
float direction = 1.0f;

// Check to see which copy of the primitive this is. If it is 0, then it
// is considered the front facing paraboloid. If it is 1, then it is
// considered the back facing paraboloid. For back facing, we reverse
// the output vertex winding order,
if ( id == 1 )
{

order.xyz = order.xzy;
direction = -1.0f;

}

// Emit three vertices for one complete triangle.