blender/intern/cycles/kernel/shaders/node_hsv.osl
Sergey Sharybin f9688d88ff Fix T42391: HSV correction shader node gives negative values
This mainly happens when over-saturating already saturated color.
After some discussion with Campbell and loads of tests we decided
to clamp the result RGB color. As an alternative we might want to
clamp corrected HSV values instead, but that would lead to some
larger changes in the render results.

TODO: The same is to be done for compositor nodes.
2014-10-31 14:58:00 +01:00

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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License
*/
#include "stdosl.h"
#include "node_color.h"
shader node_hsv(
float Hue = 0.5,
float Saturation = 1.0,
float Value = 1.0,
float Fac = 0.5,
color ColorIn = 0.0,
output color ColorOut = 0.0)
{
color Color = rgb_to_hsv(ColorIn);
// remember: fmod doesn't work for negative numbers
Color[0] += Hue + 0.5;
Color[0] = fmod(Color[0], 1.0);
Color[1] *= Saturation;
Color[2] *= Value;
Color = hsv_to_rgb(Color);
// Clamp color to prevent negative values cauzed by oversaturation.
Color[0] = max(Color[0], 0.0);
Color[1] = max(Color[1], 0.0);
Color[2] = max(Color[2], 0.0);
ColorOut = mix(ColorIn, Color, Fac);
}