poly_demo.lua

-- this program is crude and ugly sometimes ugly. But it's tutorial/demo and not good programming practices tutorial

local args = {...}

side = args[1]
point_num = args[2]

if not point_num or point_num < 1 then
    point_num = 8
end

local p = peripheral.wrap(side)
p.clear()

-- constants
INACTIVE_MARKER_COLOR = 0x0000FF
INACTIVE_MARKER_OPACITY = 0.6

ACTIVE_MARKER_COLOR = 0xFF0000
ACTIVE_MARKER_OPACITY = 1

INITIAL_COLOR = 3

DRAW_AREA_WIDTH = 200
DRAW_AREA_HEIGHT = 200

-- we use setZ to control drawing order and more importantly, order of checking component clicks
-- drawing are is separated into few layers:
LAYER_POINT_SELECTORS = 2 -- for clickable point selectors
LAYER_DRAW_AREA = 1 -- for invisible, clickable draw area. It's is needed, since only drawables report coordinates on mouse event
-- components (like THE POLYGON) by default are on layer 0
LAYER_BACKGROUND = -2 -- semi-transparent background, for showing drawing area

-- background
local background = p.addBox(0, 0, DRAW_AREA_WIDTH, DRAW_AREA_HEIGHT, 0x000000, 0.2)
background.setAlignment("middle","middle")
background.setZ(LAYER_BACKGROUND)

-- click capture box (invisible overlay)
local draw_area = p.addBox(0, 0, DRAW_AREA_WIDTH, DRAW_AREA_HEIGHT, 0xFFFFFF, 0.0)
draw_area.setAlignment("middle","middle")
draw_area.setZ(LAYER_DRAW_AREA)

-- color selectors
COLORS = {
0xEB8844,
0xC354CD,
0x6689D3,
0xDECF2A,
0x41CD34,
0xD88198,
0x434343,
0xABABAB,
0x287697,
0x7B2FBE,
0x253192,
0x51301A,
0x3B511A,
0xB3312C,
0x1E1B1B,
0xF0F0F0,
}

-- list of buttons, for updating when point selection changes
local color_buttons = {}
for meta = 1,16 do
    local button_x = (meta - 8) * 18
    local button_y = 0
    local button = p.addIcon(button_x, button_y, "minecraft:wool", meta)
    button.setAlignment("middle","bottom")
    button.setVisible(false)
    button.setUserdata({index = meta, rgb = COLORS[meta]}) -- keeping freeform data so we can later identify what was clicked
    color_buttons[meta] = button
end

-- color selection marker (just background box)
local color_marker = p.addBox(0,0,16,16, 0x000000, 0.5)
color_marker.setAlignment("middle","bottom")
color_marker.setZ(LAYER_BACKGROUND)
color_marker.setVisible(false)

-- move color selection marker under selected color
function mark_color(color_selector)
    assert(color_selector)
    color_marker.setX(color_selector.getX())
    color_marker.setY(color_selector.getY())
end

-- toggle color selector visibility
function change_color_selectors_visibility(visibility)
    for _,v in pairs(color_buttons) do
        v.setVisible(visibility)
    end

    color_marker.setVisible(visibility)
end

-- just simple method for drawing equilateral  triangles
function set_triangle_position(triangle, x, y)
    local H = 4
    local A = 2 / math.sqrt(3) * H

    triangle.setP1({x + 0, y - H * 2/3})
    triangle.setP2({x - A/2, y + H * 1/3})
    triangle.setP3({x + A/2, y + H * 1/3})
end

-- THE POLYGON
local polygon = p.addGradientPolygon()
polygon.setScreenAnchor("middle","middle")

-- triangles for marking and selecting polygons vertices
local point_markers = {}

for i = 1,point_num do
    local angle = 2 * math.pi / point_num * i
    local point_x = 80 * math.cos(angle)
    local point_y = 80 * math.sin(angle)

    -- 'points' table works like native Lua tables - setting value at index that does not exists will expand that list (all new values except last are nulls). During rendering null values are just skipped
    polygon.setPoints({point_x, point_y, COLORS[INITIAL_COLOR]}, i)

    -- creating marker triangle
    local point_marker = p.addTriangle({0,0},{0,0},{0,0}, INACTIVE_MARKER_COLOR, INACTIVE_MARKER_OPACITY)
    set_triangle_position(point_marker, point_x, point_y)
    point_marker.setZ(LAYER_POINT_SELECTORS)
    point_marker.setScreenAnchor("middle","middle")
    point_marker.setUserdata({index = i, color_index = INITIAL_COLOR}) -- again, some metadata for handling clicks
    point_markers[i] = point_marker
end

-- store intial point configuration for later
-- getPoints() returns full list, but getPoints(index) returns just single value
local initial_points = polygon.getPoints()

local reset_label = p.addText(0,0,"RESET", 0xFF0000)
reset_label.setAlignment("right","bottom")

-- currently selected point
local active_point = 1

-- change colors of all point selectors
function select_point(point_index)
    assert(point_index)
    active_point = point_index
    for _,marker in pairs(point_markers) do
        if marker.getUserdata().index == point_index then
            marker.setColor(ACTIVE_MARKER_COLOR)
            marker.setOpacity(ACTIVE_MARKER_OPACITY)
        else
            marker.setColor(INACTIVE_MARKER_COLOR)
            marker.setOpacity(INACTIVE_MARKER_OPACITY)
        end
    end
end

-- change color of currently selected point
function set_point_color(component)
    assert(component)

    local color_userdata = component.getUserdata()
    local color_index = color_userdata.index
    local rgb = color_userdata.rgb

    assert(color_index)
    assert(rgb)

    -- update polygon point
    -- getPoints() returns full list, but getPoints(index) returns just single value
    local point = polygon.getPoints(active_point)
    point.rgb = rgb

    -- same here: setPoints({...}) sets full list, but setPoints(value, index) sets single value
    polygon.setPoints(point, active_point)

    -- now we needs to update marker triangle color
    local point_marker = point_markers[active_point]
    local point_userdata = point_marker.getUserdata()
    point_userdata.color_index = color_index
    point_marker.setUserdata(point_userdata)
end

function sign(val)
 if val < 0 then return -1
 elseif val > 0 then return 1
 else return 0
 end
end

function handle_scroll(distance)
    if (distance == 0) then return end

    local selected_marker = point_markers[active_point]
    local userdata = selected_marker.getUserdata()
    local current_color = userdata.color_index

    local next_color = math.min(math.max(current_color + sign(distance), 1), 16)

    local color_selector = color_buttons[next_color]
    set_point_color(color_selector)
    mark_color(color_selector)
end

-- move currently selected point
function move_point(x, y)
    -- change point in polygon...
    local point = polygon.getPoints(active_point)
    point.x = x
    point.y = y
    polygon.setPoints(point, active_point)

    -- ... and  move marker
    set_triangle_position(point_markers[active_point], x, y)
end

function reset_polygon()
    polygon.setPoints(initial_points) -- restore initial configuration
    for i,v in ipairs(point_markers) do -- restore metadata
        v.setUserdata({index = i, color_index = INITIAL_COLOR})
        set_triangle_position(v, initial_points[i].x, initial_points[i].y)
    end
    select_point(1)
    mark_color(color_buttons[INITIAL_COLOR])
end

mark_color(color_buttons[INITIAL_COLOR])
select_point(1)

p.sync()

function pack(...)
    return {...}
end

-- setup done,  start event loop

while true do
    evt = pack(os.pullEvent())
    -- full list of glasses events: https://gist.github.com/boq/9a098b89ee102cbf1b2b
    print(evt[1])

    if evt[1] == "key" then
        break -- exit loop
    elseif evt[1] == "glasses_capture" then
        -- player uses keyboard
        local uuid = evt[4]
        local control = p.getCaptureControl(uuid)
        control.setBackground(0xFFFFFF, 0)
        -- replace hotbar with color selector
        control.toggleGuiElements({hotbar = false, crosshairs = false, health = false, armor = false, food = false, experience = false})
        change_color_selectors_visibility(true)
    elseif evt[1] == "glasses_release" then
        change_color_selectors_visibility(false)
    elseif evt[1] == "glasses_component_mouse_down" then
        -- mouse click
        local objectId = evt[5]
        local component = p.getObjectById(objectId)
        local component_type = component.getType()
        local buttonId = evt[9]
        if component_type == "triangle" and buttonId == 1 then -- right click triangle to select point
            -- point selection
            local userdata = component.getUserdata() -- {index, color_index}
            select_point(userdata.index)
            local color_selector = color_buttons[userdata.color_index]
            mark_color(color_selector)
        elseif component_type == "item" then -- click wool icon to change color of currect point
            mark_color(component)
            set_point_color(component)
        elseif objectId == draw_area.getId() and buttonId == 0 then -- left click invisible area to move to new position
            local clickX = evt[7] - DRAW_AREA_WIDTH / 2
            local clickY = evt[8] - DRAW_AREA_HEIGHT / 2

            move_point(clickX, clickY)
        elseif objectId == reset_label.getId() then
            reset_polygon()
        end
    elseif evt[1] == "glasses_mouse_scroll" then
        handle_scroll(evt[5])
    elseif evt[1] == "glasses_component_mouse_wheel" then
        handle_scroll(evt[9])
    end

    p.sync()
end