text_on.scad

/*  text on ....
    This is a rework of version 3 of write.scad to use the new OpenSCAD internal text() primitive.
    All credit to Harlan Martin (harlan@sutlog.com) for his great effort on the original.
    Great thanks to t-paul (and the OpenSCAD dev team) on adding the new text() primitive.
*/


/*
The arguments to be provided for each function are explictly in the modules.

All modules take close to all the arguments to text() [Not all features are supported in all text_on_object() modules though -- try them out warnings will be given if it is not supported]

text() params:
t
size
spacing
font
direction -- ltr, ttb, btt or rtl
language
script
halign -- left, right or center
valign -- baseline, bottom, top or center

All modules also take the additional arguments:
extrusion_height = depth of the letter, i.e. how far it sits proud
rotate
center //center the text at the location it is being written (NOT that the object is centered)

ALL faux-objects that the text is applied to have center=true
TODO: object_center=true/false (already done for cylinder)

The above arguemnts can be seen in text_extrude() as all modules call that module evetually (often multiple times).

locn_vector -- Where the faux-object has been translated to. TODO: Rename object to translate_vector?

Additional arguments for text_on_cube():

Additional arguments for text_on_cylinder():

Additional arguments for text_on_circle():

Additional arguments for text_on_sphere():


*/

// These control the default values for text_extrude(), text_on_sphere(), text_on_cube(), text_on_cylinder(), text_on_circle()
// if the arguments are not included in the call to the module.

// Defaults
// Defaults for all modules
default_t = "text_on";
default_size = 4; // TODO - Can we make this 10?? To match internal size? There is an underlying value in text() -- This masks that.
default_font = "Liberation Mono";
default_spacing = 1; // Spacing between characters. There is an underlying value in text() -- This masks that. We try and match it here.
default_rotate = 0; // text rotation (clockwise)
default_center = true; //Text-centering
default_scale = [1,1,1];
default_extrusion_height = 2; //mm letter extrusion height
default_buffer_width = 0; //mm of buffer (thickening in all directions) to add to each letter

//Defaults for Cube
default_cube_face = "front"; // default face (top,bottom,left,right,back,front)
default_sphere_rounded = false; // default for rounded letters on text_on_sphere
default_cube_updown = 0; // mm up (-down) from center on face of cube
default_cube_rightleft = 0; // mm right(-left) from center on face of cube

//Defaults for Sphere
default_sphere_northsouth = 0;
default_sphere_eastwest = 0;
default_sphere_spin = 0; // TODO:Different to rotate? or up/down. Better name?

//Defaults for Cylinder (including circle as it is on top/bottom)
default_circle_middle = 0; // (mm toward middle of circle)
default_circle_ccw = false; // write on top or bottom in a ccw direction
default_circle_eastwest = 0;
default_cylinder_face = "side";
default_cylinder_updown = 0;

// Internal values - don't play with these :)
// This is much more accurate than the PI constant internal to Openscad.
internal_pi = 3.1415926535897932384626433832795028841971693993751058209;
internal_pi2 = internal_pi * 2;

// Internal values - You might want to play with these if you are using a proportional font
internal_space_fudge = 0.80; // Fudge for working out lengths (widths) of strings

debug = true;

// ---- Helper Functions ----
// String width (length from left to right or RTL) in OpenSCAD units
// NOTE: These are innacurate because we don't know the real spacing of the chars and so have to approximate
// They work for monospaced (fixed-width) fonts well
function width_of_text_char(size, spacing) = size * internal_space_fudge * spacing;
function width_of_text_string_num_length(length, size, spacing) = width_of_text_char(size, spacing) * length;
function width_of_text_string(t, size, spacing) = width_of_text_string_num_length(len(t), size, spacing);

function cylinder_center_adjusted_top(height, center) = (center == true) ? height / 2 : height;
function cylinder_center_adjusted_bottom(height, center) = (center == true) ? height / 2 : 0;


//Angle that measures width of letters on perimeter of a circle (and sphere and cylinder)
function rotation_for_character(size, spacing, r, rotate = 0) = (width_of_text_char( size, spacing ) / (internal_pi2 * r)) * 360 * (1 - abs(rotate) / 90);


//Rotate 1/2 width of text if centering    
//One less -- if we have a single char we are already centred..
function rotation_for_center_text_string(t, size, spacing, r, rotate, center) = (center) ? (width_of_text_string_num_length(len(t) - 1, size, spacing) / 2 / (internal_pi2 * r) * 360) : 0;

//Rotate according to rotate and if centred text also 1/2 width of text
function rotation_for_center_text_string_and_rotate(t, size, spacing,r,rotate,center) = ((center) ? (width_of_text_string(t, size, spacing) / 2 / (internal_pi2 * r) * 360) : 1) * (1 - abs(rotate) / 90);


//---- Text on Object Functions ----
//Text on the top or side of a cylinder.
//Supports writing on normal and slanty cylinders
//cylinder(h,r,center)
//cylinder(h,r1,r2,center)
module text_on_cylinder(t = default_t,
                        //Object-specific                        
                        locn_vec = [0,0,0],
                        r,
                        r1,
                        r2,
                        h,
                        face = default_cylinder_face,
                        updown = default_cylinder_updown,
                        rotate = default_rotate,
                        eastwest = default_circle_eastwest,
                        middle = default_circle_middle,
                        ccw = default_circle_ccw,
                        cylinder_center = false, //if the cylinder object we are writing on is center==true
                        //TODO: add rounded
                        
                        //All objects
                        extrusion_height = default_extrusion_height,
                        center = default_center,
                        //All objects -- arguments as for text()
                        font = undef,
                        size = default_size,
                        direction = undef,
                        halign = undef,
                        valign = undef,
                        language = undef,
                        script = undef,
                        spacing = default_spacing) {

//    echo (str("text_on_cylinder:There are " ,len(t) ," letters in t" , t));
//    echo (str("text_on_cylinder:","h" , h));
//    echo (str("text_on_cylinder:","r=" , r));
//    echo (str("text_on_cylinder:","r1=" , r1));
//    echo (str("text_on_cylinder:","r2=" , r2));

    if((halign != undef) || (halign != undef)) {
        echo(str("text_on_cylinder:","WARNING " , "halign and valign are NOT supported."));
    }

    rtl_sign = (direction == "rtl") ? -1 : 1;
    if((face == "top") || (face == "bottom")) {
        //Work on a circle
        locn_offset_vec = (face == "top" ) ? [0, 0, cylinder_center_adjusted_top(h, cylinder_center)] : [0, 0, cylinder_center_adjusted_bottom(h, cylinder_center)];
        rotation_angle = (face == "top" ) ? 0 : 180;
        int_radius = (r == undef) ? ((face == "top" ) ? r2 : r1 ) : r;  //Use the top/bottom radius for slanty-cylinders
        rotate(rotation_angle, [1, 0, 0])
        text_on_circle(t,
                locn_vec + locn_offset_vec,
                r = int_radius-size,
                font = font,size=size,
                spacing = spacing,
                direction = direction,
                language = language,
                script = script,
                halign = halign,
                valign = valign,
                extrusion_height = extrusion_height,
                rotate = rotate,
                eastwest = eastwest,
                middle = middle,
                ccw = ccw);
    } else {
        if((middle != undef) && (middle != default_circle_middle)) {
            //TODO: Which others?
            //TODO: Which side things aren't supported on the circle
            echo(str("text_on_cylinder:","WARNING " , "middle NOT supported for the SIDE of a cylinder."));
        }
        //Work on the side
        locn_offset_vec = (cylinder_center == true) ? [0, 0, 0] : [0, 0, h / 2]; 
        rotate(-rtl_sign * rotation_for_center_text_string_and_rotate(t, size, spacing, r, rotate, center), [0, 0, 1])
        translate(locn_vec + locn_offset_vec)
        __internal_text_on_cylinder_side(t,
                locn_vec,
                r = r,
                h = h,
                r1 = r1,
                r2 = r2,
                cylinder_center = cylinder_center,
                center = center,
                font = font,
                size = size,
                spacing = spacing,
                direction = direction,
                language = language,
                script = script,
                halign = halign,
                valign = valign,
                extrusion_height = extrusion_height,
                rotate = rotate,
                face = face,
                updown = updown,
                eastwest = eastwest);
    }
}

//circle(r)
module text_on_circle(t = default_t,
                      //Object-specific
                      locn_vec = [0, 0, 0],
                      r,
                      eastwest = default_circle_eastwest,
                      middle = default_circle_middle,
                      ccw = default_circle_ccw,

                      //All objects                      
                      extrusion_height = default_extrusion_height,
                      rotate = default_rotate,
                      center = default_center,
                      
                      //All objects -- arguments as for text()
                      font = undef,
                      size = default_size,
                      direction = undef,
                      halign = undef,
                      valign = undef,
                      language = undef,
                      script = undef,
                      spacing = default_spacing,
                      buffer_width = default_buffer_width) {
//    echo (str("text_on_circle:","There are " ,len(t) ," letters in t" , t));
//    echo (str("text_on_circle:","rotate=" , rotate));
//    echo (str("text_on_circle:","eastwest=" , eastwest));

    if((halign != undef) || (halign != undef)) {
        echo(str("text_on_circle:","WARNING " , "halign and valign are NOT supported."));
    }

    ccw_sign = (ccw == true) ? 1 : -1;
    rtl_sign = (direction == "rtl") ? -1 : 1;
    ttb_btt_inaction = (direction == "ttb" || direction == "btt") ? 0 : 1;
    rotate_z_outer = -rotate + ccw_sign * eastwest;
    rotate_z_inner = -rtl_sign * ccw_sign * ttb_btt_inaction * rotation_for_center_text_string(t, size, spacing, r-middle, rotate, center);
    rotate(rotate_z_outer, [0, 0, 1] )
    rotate(rotate_z_inner, [0, 0, 1] )
    translate(locn_vec)
    for(l = [0 : len(t) - 1]) {
        //TTB/BTT means no per letter rotation
        rotate_z_inner2 = -ccw_sign * 90 + ttb_btt_inaction * rtl_sign * ccw_sign * l * rotation_for_character(size, spacing, r - middle, rotate = 0);   //Bottom out=-270+r
        //TTB means we go toward center, BTT means away
        vert_x_offset = (direction == "ttb" || direction == "btt") ? (l * size * ((direction == "btt") ? -1 : 1)) : 0;
        rotate(rotate_z_inner2, [0, 0, 1])
        translate([r - middle - vert_x_offset, 0, 0])
        rotate(-ccw_sign * 270, [0, 0, 1]) // flip text (botom out = -270)
        text_extrude(t[l],
                center = true,
                font = font,
                size = size,
                rotate = undef,
                spacing = spacing,
                direction = undef, //We don't pass direction ( misaligns inside text() ). TODO: Investigate why
                language = language,
                script = script,
                halign = halign,
                valign = valign,
                extrusion_height = extrusion_height,
                buffer_width = buffer_width);
    }
}

//Only expected to be called from another function. No defaults as expected to be done in parent.
//NOTE: This is hacked. Requires more mathematics than I feel like to do properly today....
//TODO: Refactor the two operations - side of normal and slanty
//No default checks in this funciton -- done in parent
module __internal_text_on_cylinder_side(t = default_t,
                      //Object-specific
                      locn_vec = [0, 0, 0],
                      r,
                      r1,
                      r2,
                      h,
                      cylinder_center,
                      
                      //All objects
                      extrusion_height = default_extrusion_height,
                      center = undef,
                      rotate = default_rotate,
                      
                      //All objects -- arguments as for text()
                      font = undef,
                      size = default_size,
                      direction = undef,
                      halign = undef, //Overridden
                      valign = undef,
                      language = undef,
                      script = undef,
                      spacing = default_spacing,
                      buffer_width = default_buffer_width) {
//    echo (str("__internal_text_on_cylinder_side:There are " ,len(t) ," letters in t" , t));
//    echo (str("__internal_text_on_cylinder_side:","h=" , h));
//    echo (str("__internal_text_on_cylinder_side:","r=" , r));
//    echo (str("__internal_text_on_cylinder_side:","r1=" , r1));
//    echo (str("__internal_text_on_cylinder_side:","r2=" , r2));
//    echo (str("__internal_text_on_cylinder_side:","direction=" , direction));
    
    if((halign != undef) || (halign != undef)) {
        echo(str("text_on_cylinder:","WARNING " , "halign and valign are NOT supported."));
    }

    wid = width_of_text_char( size, spacing ); //TODO: refactor this out?

    function calc_radius_at_height_offset(r1, r2, h_total, h_offset) = r1 + ((r2 - r1) * (h_total - h_offset) / h_total);
    
    //Has to factor in up/downedness
    //Starts at middle height then height displacement is reduced under rotation and by the slope of the uneven radii
    function calc_height_offset_at_length(r1, r2, h, length, rotate, updown) = h / 2 - updown + length * rotate / 90 * cos(atan((r2 - r1) / h));

    function calc_radius_at_length(r1, r2, h, length, rotate, updown) = calc_radius_at_height_offset(r1, r2, h, calc_height_offset_at_length(r1, r2, h, length, rotate, updown));
    
    if(r == undef) {
        //Slanty-cylinder (truncated cone) warnings
        if((direction == "btt") || (direction == "ttb")) {
            //TODO: After the issues are resolved refactoring should give this pretty easily
            echo(str("text_on_cylinder:","WARNING" , " - Slanty-cylinders definitely don't directions TTB or BTT on sides yet. Setting direction to ltr."));
        }
        if(center == true) {
            echo(str("text_on_cylinder:","WARNING" , " - Slanty-cylinders don't support centering yet. Setting center to false. You can adjust updown and eastwest and achieve most of what you are after...."));
        }
    }

    r1 = (r1 != undef) ? r1 : r;
    r2 = (r2 != undef) ? r2 : r;
    //NOTE: r is not used after here. We operate on generalised slanty cone (r1 and r2)
    
    //TODO: Look at changing this to extrusion_height_center
    //and renaming the other as text_center
    rr1 = (center) ? r1 - extrusion_height / 2 : r1;
    rr2 = (center) ? r2 - extrusion_height / 2 : r2;
    
    ccenter = (r != undef) ? center : false; //We don't do (text) centering for the slanty cones/helical paths (yet? ever?). Needs to do quite a few offset calcs.
    ddirection = ((r == undef) && ((direction == "ttb") || (direction == "btt"))) ? "ltr" : direction; //We don't do ttb or btt directions on slanty
    rtl_sign = (ddirection == "rtl") ? -1 : 1;

        //This code takes care of slanty cylinders and "normal" cylinders
    translate([0, 0, updown])
    rotate(eastwest, [0, 0, 1])
    for(l = [0 : len(t) - 1]) {
        //TODO: TTB and BTT need to have a different concept of path/length than this for RTL/LTR
           //width_of_... is half a char too long -- add 0.5 (counting from zero)
        length_to_center_of_char = width_of_text_string_num_length(l + 0.5, size, spacing);
        radius_here = calc_radius_at_length(rr1, rr2, h, length_to_center_of_char, rotate, updown);
        //Rotating into position and tangentially to surface -- Don't rotate per character for ttb/btt
        //-90 is to get centering at origin
        rotate_z_inner = -90 + rtl_sign * rotation_for_character(size, spacing, radius_here, rotate) * ((ddirection == "ttb" || ddirection== "btt") ?  0 : l);
        rotate(rotate_z_inner, [0, 0, 1]) {
            //Positioning - based on (somewhat innacurate) string length
            //Offset per character to go up/down the side in ttb/btt -- TTB down, BTT up
            vert_z_char_offset = (ddirection == "ttb" || ddirection == "btt") ?  (l * size * ((ddirection == "ttb") ? -1 : 1 )) :  0 ;
            //Only if RTL/LTR and if center -- center the text (starts off in a more visually appealing location)
            vert_z_half_text_offset_tmp = (len(t) -1) / 2 * (rotate / 90 * wid);
            vert_z_half_text_offset = ((ddirection == "ttb" || ddirection == "btt") || (ccenter == false)) ? 0 : vert_z_half_text_offset_tmp;
            translate([ radius_here , 0, vert_z_char_offset - l * (rotate / 90 * wid) + vert_z_half_text_offset])

            //Flip to tangent on the sloping side (without respecting rotation impact on the tangent -- rotate seems a little off. TODO: Investigate).
            rotate(atan((rr2 - rr1) /h), [0, 1, 0])
            //Flip onto face of "normal" cylinder
            rotate(90, [1, 0, 0])
            rotate(90, [0, 1, 0])

            //Modify the offset of the baselined text to center
            translate([0, (ccenter) ? -size / 2 : 0, 0])
        
            text_extrude(t[l],
                    center = false,
                    rotate = rotate,
                    font = font,
                    size = size,
                    spacing = spacing,
                    direction = undef, //We don't pass direction ( misaligns inside text() ). TODO: Investigate why
                    language = language,
                    script = script,
                    halign = "center", //This can be relaxed eventually
                    valign = "baseline", //Need this to keep all letters on the same line (could also support top -- otherw will make
                    extrusion_height = extrusion_height,
                    buffer_width = buffer_width);
        }
    }
}

//sphere(r)
//NB: Iterates through characters/glyphs and presents them individually (but supports actions across the entire string still)
//supports all features of text() except: halign and valign
module text_on_sphere(t = default_t,
                      //Object-specific
                      locn_vec = [0,0,0],
                      r,
                      eastwest = default_sphere_eastwest,
                      northsouth = default_sphere_northsouth,
                      rotate  = default_rotate,
                      spin = default_sphere_spin,
                      rounded  = default_sphere_rounded,
                      //All objects
                      extrusion_height = default_extrusion_height,
                      center = default_center, //center = false doesn't really even make sense to do (IMHO)
                      scale = default_scale,
                      //All objects -- arguments as for text()
                      font = undef,
                      size = default_size,
                      direction = undef,
                      halign = undef, //Not supported - only here to enable a warning
                      valign = undef, //Not supported - only here to enable a warning
                      language = undef,
                      script = undef,
                      spacing = default_spacing) {
    //echo ("text_on_sphere:There are " ,len(t) ," letters in t" , t);

    if((halign != undef) || (halign != undef)) {
        echo(str("text_on_sphere:","WARNING " , "halign and valign are NOT supported (functionality used in centering)."));
    }

    //TODO: refactor this?
    rtl_sign = (direction == "rtl") ? -1 : 1;
    
    //TODO: Look at changing this to extrusion_height_center
    //and renaming the other as text_center
    //If we are centered - we sink the radius by half the
    //extrusion height to draw "just below the surface"
    rr = (center) ? r - extrusion_height / 2 : r ;
    
    rotate(eastwest, [0, 0, 1])
    rotate(-northsouth, [1, 0, 0])
    rotate(spin, [0, 1, 0]) {
        //This tries to center the text (for RTL text).
        ttb_btt_inaction = (direction == "ttb" || direction == "btt") ? 0 : 1;
        rotate(-rtl_sign * ttb_btt_inaction * rotation_for_center_text_string(t, size, spacing, rr, rotate, center), [0, 0, 1]) {
            translate(locn_vec)
            if (rounded == false) {
                __internal_text_on_sphere_helper(t = t,
                        r = rr,
                        rotate = rotate,
                        center = center,
                        scale = scale,
                        font = font,
                        size = size,
                        spacing = spacing,
                        direction = direction,
                        language = language,
                        script = script,
                        halign = halign,
                        valign = valign,
                        extrusion_height = extrusion_height);
            } else {
                //If rounding then clip the text inside an inner sphere and outer sphere
                intersection() {
                    __internal_text_on_sphere_helper(t = t,
                            r = rr,
                            rotate = rotate,
                            center = center,
                            scale = scale,
                            font = font,
                            size = size,
                            spacing = spacing,
                            direction = direction,
                            language = language,
                            script = script,
                            halign = halign,
                            valign = valign,
                            extrusion_height = extrusion_height * 2); //Make it proud to clip it off.
                    //Shell - bounding inner and outer
                    difference() { //rounded outside
                        sphere(rr + extrusion_height);
                        // rounded inside for indented text
                        sphere( rr  );
                    }
                }
            }
        }
    }
}

//internal function -- don't call directly
//No default checks in this funciton -- done in parent
module __internal_text_on_sphere_helper(t = default_t,
                      //Object-specific
                      r,
                      //All objects
                      extrusion_height = default_extrusion_height,
                      center = default_center,
                      scale = default_scale,
                      //All objects -- arguments as for text()
                      font = undef,
                      size = default_size,
                      direction = undef,
                      //halign           = undef,
                      //valign           = undef,
                      language = undef,
                      script = undef,
                      spacing = default_spacing,
                      buffer_width = default_buffer_width) {
    rtl_sign = (direction == "rtl") ? -1 : 1;
    ttb_btt_inaction = (direction == "ttb" || direction == "btt") ? 0 : 1;
    ttb_btt_action = (direction == "ttb" || direction == "btt") ? 1 : 0;
    
    for(l = [0 : len(t) - 1]) {
        rotate_z_inner = -90 + rtl_sign * ttb_btt_inaction * l * rotation_for_character(size, spacing, r, 0);
        translate_sign = (direction == "ttb" || direction == "btt") ? ((direction == "btt") ? 1 : -1)  : 0 ;
        //translate_effect = (direction=="ttb" || direction=="btt") ? 1  :  0 ;
        //Translate letter to be located on the sphere in up/down direction when we are doing TTB and BTT
        rotate(rotate_z_inner, [0, 0, 1])
        translate(r * [cos(0 + ttb_btt_action * rotation_for_character(size, spacing, r, rotate) * l), 0, translate_sign * ttb_btt_action * sin(0 +  rotation_for_character(size, spacing, r, rotate) * l)])
        //Rotate letter to be tangential to the new part of the sphere when we are doing TTB and BTT
        rotate(-90 * translate_sign * (0 + ttb_btt_action * rotation_for_character(size, spacing, r, rotate) * l) / 90 , [0, 1, 0])
        //Flip character into position to be flush against sphere
        rotate(90, [1, 0, 0])
        rotate(90, [0, 1, 0])
    
        //Modify the offset of the baselined text to center
        translate([0, (center) ? -size / 2 : 0 , 0])
        text_extrude(t[l],
                center = false,
                rotate = rotate,
                scale = scale,
                font = font,
                size = size,
                spacing = spacing,
                direction = undef, //We don't pass direction ( misaligns inside text() ). TODO: Investigate why
                language = language,
                script = script,
                halign = "center", //This can be relaxed eventually
                valign = "baseline", //Need this to keep all letters on the same line (could also support top -- otherw will make wonky letters)
                extrusion_height = extrusion_height,
                buffer_width = buffer_width);
    }
}



//cube(size)
//cube([width,h,depth])
//NB: cube_size is used instead of size (the name size is used in the text module)
//NB: Passes through text as strings -- supports all features of text()
module text_on_cube(  t = default_t,
                      //Object-specific
                      cube_size, //number or 3-vector
                      face = default_cube_face,
                      rightleft = default_cube_rightleft,
                      updown = default_cube_updown,
                      //All objects
                      locn_vec = [0, 0, 0],
                      extrusion_height = default_extrusion_height,
                      center = undef,
                      rotate = default_rotate,
                      scale = default_scale,
                      //All objects -- arguments as for text()
                      font = undef,
                      size = default_size,
                      direction = undef,
                      halign = undef,
                      valign = undef,
                      language = undef,
                      script = undef,
                      spacing = default_spacing,
                      buffer_width = default_buffer_width) {
    //echo (str("text_on_cube:","There are " ,len(t) ," letters in t" , t));
    //echo (str("text_on_cube:","cube_size" , cube_size));
    
    if((halign != undef) || (halign != undef)) {
        echo(str("text_on_cube:","WARNING " , "halign and valign are NOT supported."));
    }

    int_cube_size = (str(cube_size)[0] != "[") ? [cube_size, cube_size, cube_size] : cube_size;
    rotate_x = ((face == "front") || (face == "back") || (face == "left") || (face == "right")) ? 90 : ((face == "bottom") ? 180 : 0); // Top is zero
    rotate_y = ((face == "back") || (face == "left") || (face == "right")) ? (face == "back") ? 180 : ((face == "left") ? -90 : 90) : 0 ; // Right is 90, Top, bottom, front are zero
    locn_vec_offset =
            (face == "front") ?               [+rightleft, -int_cube_size[1] / 2, +updown]
            : ((face == "back") ?             [+rightleft, +int_cube_size[1] / 2, +updown]
                : ((face== "left") ?          [-int_cube_size[0] / 2, +rightleft, +updown]
                    : ((face == "right") ?    [+int_cube_size[0] / 2, +rightleft, +updown]
                        : ((face == "top") ?  [+rightleft, +updown, +int_cube_size[2] / 2]
                            :                 [+rightleft, -updown, -int_cube_size[2] / 2]
                            )))); // bottom
                            
    translate(locn_vec + locn_vec_offset)
    rotate(rotate_x, [1, 0, 0])
    rotate(rotate_y, [0, 1, 0]) // rotate around the y axis (z before rotation)
    text_extrude(t,
            center = center,
            rotate = rotate,
            scale = scale,
            font = font,
            size = size,
            spacing = spacing,
            direction = direction, // Does this misalign inside text()? the individual character modules do.
            language = language,
            script = script,
            halign = halign,
            valign = valign,
            extrusion_height = extrusion_height,
            buffer_width = buffer_width );
}

function default_if_undef(val, default_val) = (val != undef) ? val : default_val;

// Print a single character or a string at the desired extrusion height
// Passes on values to text() that are passed in
// TODO: Add x,y,z rotations get text facing the right way from the start)
module text_extrude( t = default_t,
                     extrusion_height = default_extrusion_height,
                     center = default_center, // Fudgy. YMMV. // TODO:center_extrusion, or extrusion offset??
                     rotate = default_rotate,
                     scale = default_scale, // For scaling by different on axes (for widening etc)
                     // Following are test() params (in addition to t=)
                     font = default_font,
                     size = default_size,
                     direction = undef,
                     halign  = undef,
                     valign = undef,
                     language = undef,
                     script = undef,
                     spacing = default_spacing,
                     buffer_width = default_buffer_width) {
    //echo (str("text_extrude:","There are " ,len(t) ," letters in text" , t));
    //echo (str("text_extrude:","extrusion_height=" , extrusion_height));
    
    if(center == true) {
        if((halign != undef) || (valign != undef)) {
            echo(str("text_extrude:","WARNING " , "When center is true, then halign and valign are NOT supported."));
        }
    }
    
    // As arguments are explicitly set as undef (from higher functions) as they come down (they don't get defaults in this function as they are set as something)
    // we need to check and replace any that we don't want to be undef
    t = default_if_undef(t, default_t);
    font = default_if_undef(font, default_font);
    extrusion_height = default_if_undef(extrusion_height, default_extrusion_height);
    center = default_if_undef(center, default_center);
    rotate = default_if_undef(rotate, default_rotate);
    spacing = default_if_undef(spacing, default_spacing);
    size = default_if_undef(size, default_size);
    
    halign = (center) ? "center" : halign ;
    valign = (center) ? "center" : valign ;
    extrusion_center = (center) ? true : false ;
    
    scale(scale)
    rotate(rotate, [0, 0, -1]) //TODO: Do we want to make this so that the entire vector can be set?
    linear_extrude(height = extrusion_height, convexity = 10, center = extrusion_center)
    offset(delta = buffer_width)
    text(text = t,
            size = size,
            $fn = 40,
            font = font,
            direction = direction,
            spacing = spacing,
            halign = halign,
            valign = valign,
            language = language,
            script = script);
}