Hexagon.osl

/*
 * Hexagon.osl by Michel J. Anders (c)2012
 * from https://github.com/sambler/osl-shaders
 *
 * license: cc-by-sa
 *
 * original script from -
 * http://blenderthings.blogspot.co.uk/2012/11/a-hexagon-osl-shader.html
 * Modified 1/4/2020 by Saul Espinosa for Redshift 3D
 */


#define A 0.86602540378443864676372317075294 // sqrt(3)/2
#define A2 (2*A)
#define A4 (4*A)
#define SY (1/A)

shader MAhexagon
[[  string help = "Generates an RGB Hexagon Pattern",
    string label = "Hexagons" ]]
(
        vector Vector = 0,
        color Diffuse_Color1 = color(0.2, 0.8, 0.2),
        color Diffuse_Color2 = color(0.8, 0.2, 0.2),
        color Diffuse_Color3 = color(0.2, 0.2, 0.8),
        output color Color = 0,
        output int Index = 1,
        output float Distance = 0)
{
    // calculate the color

    color colors[3] = {Diffuse_Color1,
                       Diffuse_Color2,
                       Diffuse_Color3};

    // we warp the grid so that two adjacent equilateral triangles
    // are mapped to two triangles that fit in a square
    float syc = Vector[1] * SY;
    float sxc = Vector[0] + 0.5 * syc;

    int ind[18] = {1,1,3,3,3,1, 2,2,2,3,3,3, 1,2,2,2,1,1};

    int iy = int(mod(syc,3.0));
    int ix = int(mod(sxc,3.0));
    ix = iy * 6 + ix * 2 + ( mod(sxc,1.0) > mod(syc,1.0) );
    Index = ind[ix];
    Color = colors[Index-1];

    // calculate the distance to the center of the hexagon

    float sx = mod(Vector[0],3);
    float sy = mod(Vector[1]+0.75,A4);

    // map everthing to a single quadrant
    if ( sx > 1.5 ) sx = 3 - sx;
    if ( sy > A2 ) sy = A4 - sy;

    // the distance were interested in is the distance to
    // the *closest* center point
    float d1 = distance(vector(sx,sy,0),vector(1.5,A2,0));
    float d2 = distance(vector(sx,sy,0),vector(0,A,0));
    float d6 = distance(vector(sx,sy,0),vector(1.5,0,0));

    Distance = min(min(d1,d2), d6);

}