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#pragma BLENDER_REQUIRE(gpu_shader_common_color_utils.glsl)
/* Curve maps are stored in sampler objects that are evaluated in the [0, 1] range, so normalize
* parameters accordingly. */
#define NORMALIZE_PARAMETER(parameter, minimum, range) ((parameter - minimum) * range)
void node_composite_hue_correct(float factor,
vec4 color,
sampler1DArray curve_map,
const float layer,
vec3 minimums,
vec3 range_dividers,
out vec4 result)
{
vec4 hsv;
rgb_to_hsv(color, hsv);
/* First, adjust the hue channel on its own, since corrections in the saturation and value
* channels depends on the new value of the hue, not its original value. A curve map value of 0.5
* means no change in hue, so adjust the value to get an identity at 0.5. Since the identity of
* addition is 0, we subtract 0.5 (0.5 - 0.5 = 0). */
const float hue_parameter = NORMALIZE_PARAMETER(hsv.x, minimums.x, range_dividers.x);
hsv.x += texture(curve_map, vec2(hue_parameter, layer)).x - 0.5;
/* Second, adjust the saturation and value based on the new value of the hue. A curve map value
* of 0.5 means no change in hue, so adjust the value to get an identity at 0.5. Since the
* identity of duplication is 1, we multiply by 2 (0.5 * 2 = 1). */
vec2 parameters = NORMALIZE_PARAMETER(hsv.x, minimums.yz, range_dividers.yz);
hsv.y *= texture(curve_map, vec2(parameters.x, layer)).y * 2.0;
hsv.z *= texture(curve_map, vec2(parameters.y, layer)).z * 2.0;
/* Sanitize the new hue and saturation values. */
hsv.x = fract(hsv.x);
hsv.y = clamp(hsv.y, 0.0, 1.0);
hsv_to_rgb(hsv, result);
result = mix(color, result, factor);
}
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