ScreenSpace::Trace provides functionality for tracing rays in screen space to compute effects like Dynamic Reflections or any kind of ray in world space. It leverages hierarchical ray marching for efficient performance.

API Reference

static TraceResult Trace(
    const float3 Position,    // The world-space origin point of the trace.
    const float3 Direction,   // The world-space direction vector of the ray.
    const float2 vPositionSs, // Screen-space position corresponding to the origin.
    uint nMaxSteps = 64,      // Maximum steps for ray marching (default is 64).
);

The TraceResult structure represents the outcome of a trace operation:

• HitClipSpace  The hit position in clip space coordinates. With UV and Z Depth.
• Confidence  The confidence level of the hit detection.
• ValidHit Indicates whether a valid hit was found.

Usage Example

Texture2D FrameBufferCopy = /* .. */
Material m = /* .. */

float3 origin = /* world-space origin */;
float3 direction = /* world-space direction */;
float2 screenPos = /* screen-space position */;

TraceResult result = ScreenSpace::Trace(origin, direction, screenPos);

if (result.ValidHit)
{
    float3 vReflectionColor = FrameBufferCopy[ trace.HitClipSpace.xy ].rgb;
    m.Emission = lerp( m.Emission, vReflectionColor, result.Confidence );
}