//
//  CRLCurvedShadow_CurveDisplacement.cikernel
//
//  Copyright (c) 2015, 2020 Apple Inc. All rights reserved.
//

kernel float4 curveDisplacement(sampler src, float4 extent, float padding, float curveAmount) {
    float2 destCoord = destCoord();

    float2 extentOrigin = extent.xy;
    
    float2 extentSize = extent.zw;
    
    float curveOffset = (2.0 * ((destCoord.x - extentOrigin.x - padding) / (extentSize.x - (padding * 2.0)))) - 1.0;
    
    float curveDisplacement = curveOffset * curveOffset;
    
    float adjustedCurveDisplacement = curveDisplacement + ((curveAmount < 0.0) ? -1.0 : 0.0);
    
    float coordAdjust = adjustedCurveDisplacement * curveAmount;
    
    float2 finalSampleCoord = samplerTransform(src, (destCoord + float2(0, coordAdjust)));
    
    float4 resultColor = sample(src, finalSampleCoord);
    
    return resultColor;
}