UE4 Tutorial - Ultra Instinct Part 1: Aura HLSL

// Code Start
static const float PI = 3.14159265359f;
int CDIndex = 13;

Steps = clamp(floor(Steps), 1, 128);
RadialSteps = clamp(floor(RadialSteps), 1, 128);

float StepSize = Radius/Steps;                     // Step size needed to get from the center to edge of the shape
float RadialStepSize = (PI*2)/RadialSteps;                     // Step size needed to get around the object

float Result = 0.0f;

for (int i = 1; i <= Steps; i++){

float CurrentStep = i * StepSize;

for(int j = 1; j < RadialSteps; j++) {
 float Angle = j* RadialStepSize;
 float2 Coord = float2(cos(Angle), sin(Angle)) * CurrentStep + UV;

float Sample = SceneTextureLookup(ViewportUVToSceneTextureUV(Coord, CDIndex), CDIndex, false);

Result += (MaxDistance - clamp(Sample, 0, MaxDistance)) / MaxDistance;

 }
}
return float1 (Result / (RadialSteps * Steps));
// Code End