#ifndef _GRADIENT_GLSL_
#define _GRADIENT_GLSL_

#define DB_GRADIENT_MAX 16

struct Gradient_t {
    float fPosition;
    float pad0;
    float pad1;
    float pad2;
    vec4  v4Color;
};

uniform GradientBlock
{
    Gradient_t vstGradientStops[DB_GRADIENT_MAX];
};

vec4 getGradientColor(float position, int index, int count)
{
    position = clamp(position, 0, 1);

    int i0 = 0;
    float p0 = vstGradientStops[index + i0].fPosition;

    int i1 = count - 1;
    float p1 = vstGradientStops[index + i1].fPosition;

    for (int i = 0; i < count; i++)
    {
        float px = vstGradientStops[index + i].fPosition;

        if (px > p0 && px <= position)
        {
            p0 = px;
            i0 = i;
        }

        if (px < p1 && px >= position)
        {
            p1 = px;
            i1 = i;
        }
    }

    vec4 c0 = vstGradientStops[index + i0].v4Color;
    vec4 c1 = vstGradientStops[index + i1].v4Color;

    float l = p1 - p0;
    float w = (l > 0) ? (position - p0) / (p1 - p0) : 0;

    return mix(c0, c1, w);
}

#endif