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float calc_gradient(vec3 p, int gradient_type)
{
float x, y, z;
x = p.x;
y = p.y;
z = p.z;
if (gradient_type == 0) { /* linear */
return x;
}
else if (gradient_type == 1) { /* quadratic */
float r = max(x, 0.0);
return r * r;
}
else if (gradient_type == 2) { /* easing */
float r = min(max(x, 0.0), 1.0);
float t = r * r;
return (3.0 * t - 2.0 * t * r);
}
else if (gradient_type == 3) { /* diagonal */
return (x + y) * 0.5;
}
else if (gradient_type == 4) { /* radial */
return atan(y, x) / (M_PI * 2) + 0.5;
}
else {
/* Bias a little bit for the case where p is a unit length vector,
* to get exactly zero instead of a small random value depending
* on float precision. */
float r = max(0.999999 - sqrt(x * x + y * y + z * z), 0.0);
if (gradient_type == 5) { /* quadratic sphere */
return r * r;
}
else if (gradient_type == 6) { /* sphere */
return r;
}
}
return 0.0;
}
void node_tex_gradient(vec3 co, float gradient_type, out vec4 color, out float fac)
{
float f = calc_gradient(co, int(gradient_type));
f = clamp(f, 0.0, 1.0);
color = vec4(f, f, f, 1.0);
fac = f;
}
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