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#define PI180 0.0174533f
#define SQRT3 0.5773503f
#define LUM_R 0.299f
#define LUM_G 0.587f
#define LUM_B 0.114f
#define SIN30 0.5f
#define COS30 0.8660254f
#define PI 3.141592654f
#define PI2 6.283185307f
#define mod(x, y) (x - y * floor(x / y))
// Convert pre-multiplied rgba values
// to linear rgba.
float4 pmrgba_to_rgba(float4 color)
{
return saturate(float4(color.rgb / color.a, color.a));
}
float4 adjust_brightness(float4 color, float brightness)
{
return saturate(float4(color.rgb + brightness, color.a));
}
float4 adjustments(float4 color, float b, float c, float s, float hue_shift) {
// Calculate Contrast Value
float ca = c < 0.0f ? 1.0f / (-c + 1.0f) : (c + 1.0f);
// Calculate Saturation Values
float s_r = (1.0f - s) * LUM_R;
float s_g = (1.0f - s) * LUM_G;
float s_b = (1.0f - s) * LUM_B;
float3 col = float3(
ca * (s_r + s) * color.r + ca * s_g * color.g + ca * s_b * color.b + b,
ca * s_r * color.r + ca * (s_g + s) * color.g + ca * s_b * color.b + b,
ca * s_r * color.r + ca * s_g * color.g + ca * (s_b + s) * color.b + b
);
// Calculate Hue shift values
float half_angle = 0.5f * hue_shift * PI180;
float rq = SQRT3 * sin(half_angle);
float cross = rq * rq;
float sq = 2.0f * cross;
float d = 2.0f * (0.5f - sq);
float w_imag = rq * cos(half_angle);
float a_l = 2.0f * (cross + w_imag);
float b_l = 2.0f * (cross - w_imag);
return saturate(float4(
col.r * d + col.g * a_l + col.b * b_l,
col.r * b_l + col.g * d + col.b * a_l,
col.r * a_l + col.g * b_l + col.b * d,
color.a
));
}
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