svm_hsv.h

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/*
 * Copyright 2011, Blender Foundation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#ifndef __SVM_HSV_H__
#define __SVM_HSV_H__

CCL_NAMESPACE_BEGIN

__device float3 rgb_to_hsv(float3 rgb)
{
    float cmax, cmin, h, s, v, cdelta;
    float3 c;

    cmax = fmaxf(rgb.x, fmaxf(rgb.y, rgb.z));
    cmin = min(rgb.x, min(rgb.y, rgb.z));
    cdelta = cmax - cmin;

    v = cmax;

    if(cmax != 0.0f) {
        s = cdelta/cmax;
    }
    else {
        s = 0.0f;
        h = 0.0f;
    }

    if(s == 0.0f) {
        h = 0.0f;
    }
    else {
        float3 cmax3 = make_float3(cmax, cmax, cmax);
        c = (cmax3 - rgb)/cdelta;

        if(rgb.x == cmax) h = c.z - c.y;
        else if(rgb.y == cmax) h = 2.0f + c.x -  c.z;
        else h = 4.0f + c.y - c.x;

        h /= 6.0f;

        if(h < 0.0f)
            h += 1.0f;
    }

    return make_float3(h, s, v);
}

__device float3 hsv_to_rgb(float3 hsv)
{
    float i, f, p, q, t, h, s, v;
    float3 rgb;

    h = hsv.x;
    s = hsv.y;
    v = hsv.z;

    if(s==0.0f) {
        rgb = make_float3(v, v, v);
    }
    else {
        if(h==1.0f)
            h = 0.0f;
        
        h *= 6.0f;
        i = floor(h);
        f = h - i;
        rgb = make_float3(f, f, f);
        p = v*(1.0f-s);
        q = v*(1.0f-(s*f));
        t = v*(1.0f-(s*(1.0f-f)));
        
        if(i == 0.0f) rgb = make_float3(v, t, p);
        else if(i == 1.0f) rgb = make_float3(q, v, p);
        else if(i == 2.0f) rgb = make_float3(p, v, t);
        else if(i == 3.0f) rgb = make_float3(p, q, v);
        else if(i == 4.0f) rgb = make_float3(t, p, v);
        else rgb = make_float3(v, p, q);
    }

    return rgb;
}

__device void svm_node_hsv(KernelGlobals *kg, ShaderData *sd, float *stack, uint in_color_offset, uint fac_offset, uint out_color_offset, int *offset)
{
    /* read extra data */
    uint4 node1 = read_node(kg, offset);

    float fac = stack_load_float(stack, fac_offset);
    float3 in_color = stack_load_float3(stack, in_color_offset);
    float3 color = in_color;

    float hue = stack_load_float(stack, node1.y);
    float sat = stack_load_float(stack, node1.z);
    float val = stack_load_float(stack, node1.w);

    color = rgb_to_hsv(color);

    // remember: fmod doesn't work for negative numbers
    color.x += hue + 0.5f;
    color.x = fmod(color.x, 1.0f);
    color.y *= sat;
    color.z *= val;

    color = hsv_to_rgb(color);

    color.x = fac*color.x + (1.0f - fac)*in_color.x;
    color.y = fac*color.y + (1.0f - fac)*in_color.y;
    color.z = fac*color.z + (1.0f - fac)*in_color.z;

    if (stack_valid(out_color_offset))
        stack_store_float3(stack, out_color_offset, color);
}

CCL_NAMESPACE_END

#endif /* __SVM_HSV_H__ */