__DEVICE__ float apply_linear_contrast(float in, float contrast, float pivot)

{
    
float out;

out = (in - pivot) * contrast + pivot;

return out;

}

__DEVICE__ float apply_rolling_contrast(float in, float contrast, float pivot)

{
 
float out;
float zerocheck = 1.f;

if (in <= pivot) {
    
out = _powf((in / pivot), contrast) * pivot;


}

else {
    
in = 1 - in;
pivot = 1 - pivot;

if (in < 0.f) {
    
zerocheck = -1.f;

}

out = (_powf((in / pivot), contrast) * pivot) * zerocheck;

out = 1 - out;


}

return out;



}

__DEVICE__ float3 apply_highlight_split(float3 in, float strength, float color_mix)

{
    
float3 out = in;

float red_strength = ((1 - color_mix) * strength) + 1.f;
float green_strength = (color_mix * strength) + 1.f;

out.x = in.x * red_strength;
out.y = in.y * green_strength;

return out;

}


__DEVICE__ float3 apply_shadow_split(float3 in, float strength, float color_mix)

{
    
float3 out = in;

in.x = (1 - in.x);
in.y = (1 - in.y);
in.z = (1 - in.z);

float green_strength = (color_mix * strength) + 1.f;
float blue_strength = ((1 - color_mix) * strength) + 1.f;

out.x = in.x;
out.y = in.y / green_strength;
out.z = in.z / blue_strength;


out.x = (1 - out.x);
out.y = (1 - out.y);
out.z = (1 - out.z);

return out;




}


DEFINE_UI_PARAMS(contrast, Contrast, DCTLUI_SLIDER_FLOAT, 1.0, 0.0, 2.0, 0.1)
DEFINE_UI_PARAMS(pivot, Pivot, DCTLUI_SLIDER_FLOAT, .435, 0.0, 1.0, 0.1)
DEFINE_UI_PARAMS(contrast_type, Contrast Type, DCTLUI_COMBO_BOX, 0, { linear, S_curve }, { Linear, S-Curve })
DEFINE_UI_PARAMS(split_strength, Split Tone Strength, DCTLUI_SLIDER_FLOAT, 0.0, 0.0, 1.0, .1)
DEFINE_UI_PARAMS(split_shadow_color_mix, Blue/Green Shadows, DCTLUI_SLIDER_FLOAT, .5, 0.0, 1.0, .1)
DEFINE_UI_PARAMS(split_highlight_color_mix, Red/Green Highlights, DCTLUI_SLIDER_FLOAT, .5, 0.0, 1.0, .1)

__DEVICE__ float3 transform(int p_Width, int p_Height, int p_X, int p_Y, float p_R, float p_G, float p_B)
{
    
    float3 in = {p_R, p_G, p_B};
    float3 out;

    if (contrast_type == linear) {


    out.x = apply_linear_contrast(in.x, contrast, pivot);
    out.y = apply_linear_contrast(in.y, contrast, pivot);
    out.z = apply_linear_contrast(in.z, contrast, pivot);


    }

    if (contrast_type == S_curve) {

    out.x = apply_rolling_contrast(in.x, contrast, pivot);
    out.y = apply_rolling_contrast(in.y, contrast, pivot);
    out.z = apply_rolling_contrast(in.z, contrast, pivot);



    }


    out = apply_shadow_split(out, split_strength, split_shadow_color_mix);
    out = apply_highlight_split(out, split_strength, split_highlight_color_mix);


    return out;
}