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imgui-luau/imgui/backend/imgui_impl_roblox.lua
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Lua

--- ImGui Backend for Roblox
--- - Renderer: exact software rasterizer (1:1 with imgui's triangles) into 256x256 EditableImage tiles at native
--- screen resolution; only tiles whose content changed are redrawn/uploaded (see RenderDrawData).
--- - Platform: UserInputService
--- - Files: an in-memory file system (VFS), pre-filled with the fonts from imgui_impl_roblox_fonts.lua
--- Requires "Allow Mesh / Image APIs" (EditableImage) in game settings.
local UserInputService = game:GetService("UserInputService")
local Players = game:GetService("Players")
local AssetService = game:GetService("AssetService")
local floor, ceil, min, max = math.floor, math.ceil, math.min, math.max
local readu8, readu32, writeu32, readstring = buffer.readu8, buffer.readu32, buffer.writeu32, buffer.readstring
local band, rshift = bit32.band, bit32.rshift
local ImGui_ImplRoblox_GetBackendData
local ImGui_ImplRoblox_UpdateTexture
local ImGui_ImplRoblox_RenderDrawData
local ImGui_ImplRoblox_Shutdown
local KEY_MAP = {} -- Enum.KeyCode -> ImGuiKey
do
local names = {
Return = "Enter", Escape = "Escape", Backspace = "Backspace", Tab = "Tab", Space = "Space", KeypadEnter = "KeypadEnter",
Up = "UpArrow", Down = "DownArrow", Left = "LeftArrow", Right = "RightArrow",
Home = "Home", End = "End", PageUp = "PageUp", PageDown = "PageDown", Insert = "Insert", Delete = "Delete",
LeftControl = "LeftCtrl", RightControl = "RightCtrl", LeftShift = "LeftShift", RightShift = "RightShift",
LeftAlt = "LeftAlt", RightAlt = "RightAlt", LeftSuper = "LeftSuper", RightSuper = "RightSuper",
Quote = "Apostrophe", Comma = "Comma", Minus = "Minus", Period = "Period", Slash = "Slash", Semicolon = "Semicolon",
Equals = "Equal", LeftBracket = "LeftBracket", BackSlash = "Backslash", RightBracket = "RightBracket", Backquote = "GraveAccent",
CapsLock = "CapsLock",
KeypadPeriod = "KeypadDecimal", KeypadDivide = "KeypadDivide", KeypadMultiply = "KeypadMultiply",
KeypadMinus = "KeypadSubtract", KeypadPlus = "KeypadAdd", KeypadEquals = "KeypadEqual",
}
local digits = { "Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine" }
for i = 0, 9 do
names[digits[i + 1]] = "K" .. i
names["Keypad" .. digits[i + 1]] = "Keypad" .. i
end
for i = 1, 12 do names["F" .. i] = "F" .. i end
for c in ("ABCDEFGHIJKLMNOPQRSTUVWXYZ"):gmatch(".") do names[c] = c end
for rbx_name, imgui_name in pairs(names) do
KEY_MAP[Enum.KeyCode[rbx_name]] = ImGuiKey[imgui_name]
end
end
-- Roblox has no "text input" event, so characters come from KeyCode.Value (ASCII for printable keys) + a US layout shift table.
local SHIFTED = {
["1"] = "!", ["2"] = "@", ["3"] = "#", ["4"] = "$", ["5"] = "%", ["6"] = "^", ["7"] = "&", ["8"] = "*", ["9"] = "(", ["0"] = ")",
["-"] = "_", ["="] = "+", ["["] = "{", ["]"] = "}", ["\\"] = "|", [";"] = ":", ["'"] = "\"", [","] = "<", ["."] = ">", ["/"] = "?", ["`"] = "~",
}
local MOUSE_BUTTONS = {
[Enum.UserInputType.MouseButton1] = 0, -- ImGuiMouseButton.Left
[Enum.UserInputType.MouseButton2] = 1, -- ImGuiMouseButton.Right
[Enum.UserInputType.MouseButton3] = 2, -- ImGuiMouseButton.Middle
}
--- @return boolean ctrl, boolean shift, boolean alt
local function ImGui_ImplRoblox_UpdateKeyModifiers()
local io = ImGui.GetIO()
local K = Enum.KeyCode
local ctrl = UserInputService:IsKeyDown(K.LeftControl) or UserInputService:IsKeyDown(K.RightControl)
local shift = UserInputService:IsKeyDown(K.LeftShift) or UserInputService:IsKeyDown(K.RightShift)
local alt = UserInputService:IsKeyDown(K.LeftAlt) or UserInputService:IsKeyDown(K.RightAlt)
io:AddKeyEvent(ImGuiMod_Ctrl, ctrl)
io:AddKeyEvent(ImGuiMod_Shift, shift)
io:AddKeyEvent(ImGuiMod_Alt, alt)
io:AddKeyEvent(ImGuiMod_Super, UserInputService:IsKeyDown(K.LeftSuper) or UserInputService:IsKeyDown(K.RightSuper))
return ctrl, shift, alt
end
--- @return table?
function ImGui_ImplRoblox_GetBackendData()
return ImGui.GetCurrentContext() and ImGui.GetIO().BackendPlatformUserData or nil
end
local function ImGui_ImplRoblox_UpdateMonitors(w, h)
local platform_io = ImGui.GetPlatformIO()
platform_io.Monitors:resize(0)
local imgui_monitor = ImGuiPlatformMonitor()
ImVec2_Copy(imgui_monitor.MainSize, ImVec2(w, h))
ImVec2_Copy(imgui_monitor.WorkSize, ImVec2(w, h))
platform_io.Monitors:push_back(imgui_monitor)
end
---------------------------------------------------------
-- PLATFORM DATA & CALLBACKS
---------------------------------------------------------
-- Games can't touch the OS clipboard, so copy/paste only works inside ImGui
local clipboard = ""
local function ImGui_ImplRoblox_PlatformSetClipboardText(ctx, text) clipboard = text end
local function ImGui_ImplRoblox_PlatformGetClipboardText(ctx) return clipboard end
---------------------------------------------------------
-- FILE SYSTEM (in-memory, Roblox has no file access)
---------------------------------------------------------
local VFS = {} -- path -> string of raw bytes
--- Registers a file so ImGui can load it, e.g. ImGui_ImplRoblox.AddFile("fonts/MyFont.ttf", bytes)
--- then io.Fonts:AddFontFromFileTTF("fonts/MyFont.ttf", 16)
local function ImGui_ImplRoblox_AddFile(path, bytes) VFS[path] = bytes end
for path, hex in pairs(IM_INCLUDE("imgui_impl_roblox_fonts.lua")) do
VFS[path] = hex:gsub("%s", ""):gsub("%x%x", function(h) return string.char(tonumber(h, 16)) end)
end
function ImStd.ImFileOpen(filename, mode)
local data = VFS[filename]
return data and { Data = data, Pos = 0 } or nil
end
function ImStd.ImFileClose(f) end
function ImStd.ImFileGetSize(f) return #f.Data end
function ImStd.ImFileRead(f, data, count)
local s, pos = f.Data, f.Pos
count = min(count, #s - pos)
for i = 1, count do data[i] = string.byte(s, pos + i) end
f.Pos = pos + count
return count
end
function ImStd.ImFileLoadToMemory(filename, mode)
local f = ImStd.ImFileOpen(filename, mode)
if not f or #f.Data == 0 then return end
local file_data = {}
local size = ImStd.ImFileRead(f, file_data, #f.Data)
return file_data, size
end
---------------------------------------------------------
-- TEXTURE MANAGEMENT
---------------------------------------------------------
-- Copies a region of ImTextureData pixels (1-based byte table) into our RGBA8 buffer
local function CopyTexturePixels(tex, dst, x, y, w, h)
local bpp, tex_w = tex.BytesPerPixel, tex.Width
for row = 0, h - 1 do
local src, src_base = tex:GetPixelsAt(x, y + row)
local dst_off = ((y + row) * tex_w + x) * 4
if bpp == 4 then
for i = 0, w - 1 do
local s = src_base + i * 4
writeu32(dst, dst_off + i * 4, src[s] + src[s + 1] * 256 + src[s + 2] * 65536 + src[s + 3] * 16777216)
end
else -- Alpha8: white with alpha
for i = 0, w - 1 do
writeu32(dst, dst_off + i * 4, 16777215 + src[src_base + i] * 16777216)
end
end
end
end
function ImGui_ImplRoblox_UpdateTexture(tex)
local bd = ImGui_ImplRoblox_GetBackendData()
if tex.Status == ImTextureStatus.WantCreate then
local t = { Buffer = buffer.create(tex.Width * tex.Height * 4), Width = tex.Width, Height = tex.Height }
CopyTexturePixels(tex, t.Buffer, 0, 0, tex.Width, tex.Height)
bd.TextureCount = bd.TextureCount + 1
bd.Textures[bd.TextureCount] = t
tex.BackendUserData = bd.TextureCount
tex:SetTexID(bd.TextureCount)
tex:SetStatus(ImTextureStatus.OK)
elseif tex.Status == ImTextureStatus.WantUpdates then
local t = bd.Textures[tex.BackendUserData]
IM_ASSERT(t ~= nil)
for _, r in tex.Updates:iter() do
CopyTexturePixels(tex, t.Buffer, r.x, r.y, r.w, r.h)
end
tex:SetStatus(ImTextureStatus.OK)
elseif tex.Status == ImTextureStatus.WantDestroy then
if tex.BackendUserData then
bd.Textures[tex.BackendUserData] = nil
tex.BackendUserData = nil
end
tex:SetTexID(ImTextureID_Invalid)
tex:SetStatus(ImTextureStatus.Destroyed)
end
end
---------------------------------------------------------
-- RENDERING (software rasterizer into tile buffers)
---------------------------------------------------------
-- Buffer layout: 4 bytes per pixel, R G B A, row-major, 0-based offsets. ImU32 colours are already R | G<<8 | B<<16 | A<<24.
-- Blending is non-premultiplied "over" with a transparent (alpha 0) background, so the game stays visible behind ImGui.
local buf, buf_w -- buffer/width of the tile being drawn
local TILE_SIZE -- Vector2, set below
-- Blends one pixel (r, g, b, a are 0..255). One u32 read/write, one division in the general case.
-- FillSpan below inlines the same math with per-span constants - keep the two in sync.
@native
local function BlendPixel(o, r, g, b, a)
if a >= 255 then
writeu32(buf, o, floor(r + 0.5) + floor(g + 0.5) * 256 + floor(b + 0.5) * 65536 + 4278190080)
return
end
if a <= 0 then return end
local d = readu32(buf, o)
local da = rshift(d, 24)
if da == 0 then
writeu32(buf, o, floor(r + 0.5) + floor(g + 0.5) * 256 + floor(b + 0.5) * 65536 + floor(a + 0.5) * 16777216)
return
end
local sa = a / 255
local dr, dg, db = band(d, 255), band(rshift(d, 8), 255), band(rshift(d, 16), 255)
if da == 255 then
local ns = 1 - sa
writeu32(buf, o, floor(r * sa + dr * ns + 0.5) + floor(g * sa + dg * ns + 0.5) * 256 + floor(b * sa + db * ns + 0.5) * 65536 + 4278190080)
else
local k = da * ((1 - sa) / 255)
local oa = sa + k
local inv = 1 / oa
writeu32(buf, o, floor((r * sa + dr * k) * inv + 0.5) + floor((g * sa + dg * k) * inv + 0.5) * 256
+ floor((b * sa + db * k) * inv + 0.5) * 65536 + floor(oa * 255 + 0.5) * 16777216)
end
end
-- Fills pixels [x0, x1) of row y with one colour
@native
local function FillSpan(y, x0, x1, r, g, b, a)
if a <= 0 then return end
local o0 = (y * buf_w + x0) * 4
local o1 = o0 + (x1 - x0 - 1) * 4
if a >= 255 then
local packed = floor(r + 0.5) + floor(g + 0.5) * 256 + floor(b + 0.5) * 65536 + 4278190080
for o = o0, o1, 4 do writeu32(buf, o, packed) end
return
end
local packed0 = floor(r + 0.5) + floor(g + 0.5) * 256 + floor(b + 0.5) * 65536 + floor(a + 0.5) * 16777216
local sa = a / 255
local ns = 1 - sa
local c1 = ns / 255
local rs, gs, bs = r * sa, g * sa, b * sa
local last_d, last_v = -1, 0 -- UI backgrounds are mostly flat: reuse the previous result for the same destination
for o = o0, o1, 4 do
local d = readu32(buf, o)
local da = rshift(d, 24)
if d == last_d then
writeu32(buf, o, last_v)
elseif da == 0 then
writeu32(buf, o, packed0)
else
last_d = d
local dr, dg, db = band(d, 255), band(rshift(d, 8), 255), band(rshift(d, 16), 255)
if da == 255 then
last_v = floor(rs + dr * ns + 0.5) + floor(gs + dg * ns + 0.5) * 256 + floor(bs + db * ns + 0.5) * 65536 + 4278190080
else
local k = da * c1
local oa = sa + k
local inv = 1 / oa
last_v = floor((rs + dr * k) * inv + 0.5) + floor((gs + dg * k) * inv + 0.5) * 256
+ floor((bs + db * k) * inv + 0.5) * 65536 + floor(oa * 255 + 0.5) * 16777216
end
writeu32(buf, o, last_v)
end
end
end
@native
local function UnpackColor(col)
return col % 256, floor(col / 256) % 256, floor(col / 65536) % 256, floor(col / 16777216) % 256
end
-- Nearest texel at (u, v) as r, g, b, a (0..255)
@native
local function SampleTexture(t, u, v)
local tw, th = t.Width, t.Height
local tx, ty = floor(u * tw), floor(v * th)
if tx < 0 then tx = 0 elseif tx >= tw then tx = tw - 1 end
if ty < 0 then ty = 0 elseif ty >= th then ty = th - 1 end
local o = (ty * tw + tx) * 4
local tb = t.Buffer
return readu8(tb, o), readu8(tb, o + 1), readu8(tb, o + 2), readu8(tb, o + 3)
end
-- Axis aligned, single colour quad (rects, glyphs, images). Pixel centers inside [x0, x1) x [y0, y1) are drawn.
@native
local function DrawRect(x0, y0, x1, y1, u0, v0, u1, v1, col, t, cx0, cy0, cx1, cy1)
local r, g, b, a = UnpackColor(col)
if a == 0 then return end
local px0, py0 = max(ceil(x0 - 0.5), cx0), max(ceil(y0 - 0.5), cy0)
local px1, py1 = min(ceil(x1 - 0.5), cx1), min(ceil(y1 - 0.5), cy1)
if px0 >= px1 or py0 >= py1 then return end
if not t or (u0 == u1 and v0 == v1) then
if t then
local tr, tg, tb, ta = SampleTexture(t, u0, v0)
r, g, b, a = r * tr / 255, g * tg / 255, b * tb / 255, a * ta / 255
end
if a <= 0 then return end
-- Rows of a flat rect usually blend over identical rows: when this row's destination equals the previous
-- row's (exact string compare), the result is identical too, so memcpy the previous row's result.
local len = (px1 - px0) * 4
local prev_dst, prev_o = nil, 0
for y = py0, py1 - 1 do
local o = (y * buf_w + px0) * 4
if a >= 255 then
if prev_dst then buffer.copy(buf, o, buf, prev_o, len) else FillSpan(y, px0, px1, r, g, b, a); prev_dst = true end
else
local dst = readstring(buf, o, len)
if dst == prev_dst then
buffer.copy(buf, o, buf, prev_o, len)
else
FillSpan(y, px0, px1, r, g, b, a)
prev_dst = dst
end
end
prev_o = o
end
return
end
local du, dv = (u1 - u0) / (x1 - x0), (v1 - v0) / (y1 - y0)
local tw, th, tbuf = t.Width, t.Height, t.Buffer
local r255, g255, b255, a255 = r / 255, g / 255, b / 255, a / 255
for y = py0, py1 - 1 do
local ty = floor((v0 + (y + 0.5 - y0) * dv) * th)
if ty < 0 then ty = 0 elseif ty >= th then ty = th - 1 end
local trow = ty * tw
local o = (y * buf_w + px0) * 4
for x = px0, px1 - 1 do
local tx = floor((u0 + (x + 0.5 - x0) * du) * tw)
if tx < 0 then tx = 0 elseif tx >= tw then tx = tw - 1 end
local to = (trow + tx) * 4
local ta = readu8(tbuf, to + 3)
if ta > 0 then
BlendPixel(o, readu8(tbuf, to) * r255, readu8(tbuf, to + 1) * g255, readu8(tbuf, to + 2) * b255, ta * a255)
end
o = o + 4
end
end
end
-- Generic triangle: per-vertex colour + uv, top-left fill rule, clipped to [cx0, cx1) x [cy0, cy1)
@native
local function DrawTriangle(va, vb, vc, t, cx0, cy0, cx1, cy1, ox, oy)
local x0, y0 = va[1][1] - ox, va[1][2] - oy
local x1, y1 = vb[1][1] - ox, vb[1][2] - oy
local x2, y2 = vc[1][1] - ox, vc[1][2] - oy
local area = (x1 - x0) * (y2 - y0) - (y1 - y0) * (x2 - x0)
if area == 0 then return end
if area < 0 then -- make the winding consistent so "inside" means all edge functions >= 0
vb, vc = vc, vb
x1, y1, x2, y2 = x2, y2, x1, y1
area = -area
end
local minx, maxx = max(floor(min(x0, x1, x2)), cx0), min(ceil(max(x0, x1, x2)), cx1 - 1)
local miny, maxy = max(floor(min(y0, y1, y2)), cy0), min(ceil(max(y0, y1, y2)), cy1 - 1)
if minx > maxx or miny > maxy then return end
-- Edge functions E(p) = A*px + B*py + C, w0 is opposite va, w1 opposite vb, w2 opposite vc
local A0, B0 = y1 - y2, x2 - x1; local C0 = -(A0 * x1 + B0 * y1)
local A1, B1 = y2 - y0, x0 - x2; local C1 = -(A1 * x2 + B1 * y2)
local A2, B2 = y0 - y1, x1 - x0; local C2 = -(A2 * x0 + B2 * y0)
local tl0 = A0 > 0 or (A0 == 0 and B0 > 0)
local tl1 = A1 > 0 or (A1 == 0 and B1 > 0)
local tl2 = A2 > 0 or (A2 == 0 and B2 > 0)
local inv = 1 / area
local ra, ga, ba, aa = UnpackColor(va[3])
local rb, gb, bb, ab = UnpackColor(vb[3])
local rc, gc, bc, ac = UnpackColor(vc[3])
local ua, vva, ub, vvb, uc, vvc = va[2][1], va[2][2], vb[2][1], vb[2][2], vc[2][1], vc[2][2]
local textured = t and not (ua == ub and ua == uc and vva == vvb and vva == vvc)
if t and not textured then -- constant uv (e.g. the atlas white pixel): fold the texel into the vertex colours
local tr, tg, tb, ta = SampleTexture(t, ua, vva)
ra, ga, ba, aa = ra * tr / 255, ga * tg / 255, ba * tb / 255, aa * ta / 255
rb, gb, bb, ab = rb * tr / 255, gb * tg / 255, bb * tb / 255, ab * ta / 255
rc, gc, bc, ac = rc * tr / 255, gc * tg / 255, bc * tb / 255, ac * ta / 255
end
local flat = not textured and ra == rb and ra == rc and ga == gb and ga == gc and ba == bb and ba == bc and aa == ab and aa == ac
if flat and aa <= 0 then return end
for y = miny, maxy do
local py = y + 0.5
-- Narrow the x range of this row using the edges (expanded by one pixel, exact test below)
local xl, xr = minx, maxx
local e0, e1, e2 = B0 * py + C0, B1 * py + C1, B2 * py + C2
if A0 ~= 0 then local xe = -e0 / A0 - 0.5; if A0 > 0 then xl = max(xl, floor(xe)) else xr = min(xr, ceil(xe)) end end
if A1 ~= 0 then local xe = -e1 / A1 - 0.5; if A1 > 0 then xl = max(xl, floor(xe)) else xr = min(xr, ceil(xe)) end end
if A2 ~= 0 then local xe = -e2 / A2 - 0.5; if A2 > 0 then xl = max(xl, floor(xe)) else xr = min(xr, ceil(xe)) end end
local row = y * buf_w
for x = xl, xr do
local px = x + 0.5
local w0, w1, w2 = A0 * px + e0, A1 * px + e1, A2 * px + e2
if (w0 > 0 or (w0 == 0 and tl0)) and (w1 > 0 or (w1 == 0 and tl1)) and (w2 > 0 or (w2 == 0 and tl2)) then
local o = (row + x) * 4
if flat then
BlendPixel(o, ra, ga, ba, aa)
else
w0, w1, w2 = w0 * inv, w1 * inv, w2 * inv
local r = w0 * ra + w1 * rb + w2 * rc
local g = w0 * ga + w1 * gb + w2 * gc
local b = w0 * ba + w1 * bb + w2 * bc
local a = w0 * aa + w1 * ab + w2 * ac
if textured then
local tr, tg, tb, ta = SampleTexture(t, w0 * ua + w1 * ub + w2 * uc, w0 * vva + w1 * vvb + w2 * vvc)
r, g, b, a = r * tr / 255, g * tg / 255, b * tb / 255, a * ta / 255
end
BlendPixel(o, r, g, b, a)
end
end
end
end
end
-- Quads emitted by PrimRect/PrimRectUV/RenderText use indices (a, b, c, a, c, d) with a=TL, b=TR, c=BR, d=BL.
-- When such a quad is axis aligned with one colour it is drawn with the much cheaper DrawRect.
@native
local function TryDrawRect(va, vb, vc, vd, t, cx0, cy0, cx1, cy1, ox, oy)
local pa, pb, pc, pd = va[1], vb[1], vc[1], vd[1]
if not (pa[2] == pb[2] and pb[1] == pc[1] and pc[2] == pd[2] and pd[1] == pa[1] and pa[1] < pb[1] and pa[2] < pd[2]) then return false end
local col = va[3]
if vb[3] ~= col or vc[3] ~= col or vd[3] ~= col then return false end
local ta, tb, tc, td = va[2], vb[2], vc[2], vd[2]
if not (tb[1] == tc[1] and tb[2] == ta[2] and td[1] == ta[1] and td[2] == tc[2]) then return false end
DrawRect(pa[1] - ox, pa[2] - oy, pc[1] - ox, pc[2] - oy, ta[1], ta[2], tc[1], tc[2], col, t, cx0, cy0, cx1, cy1)
return true
end
-- Tiles: the screen is covered by TILE x TILE EditableImages (one ImageLabel each). Every frame each primitive
-- (triangle, or axis aligned quad) is hashed into the tiles it touches; only tiles whose hash changed are
-- re-rasterized and uploaded. Static UI therefore costs ~nothing to draw, and the result is pixel-identical to a
-- full redraw (the hash covers everything that affects a tile's pixels: geometry, uv, colour, texture, clip, order).
local TILE = 256
TILE_SIZE = Vector2.new(TILE, TILE)
local P1, P2 = 2147483647, 2147483629 -- two independent 31 bit hashes per tile (collision odds ~2^-62)
-- Primitive arrays (reused between frames, no per-frame allocation)
local pr_a, pr_b, pr_c, pr_d, pr_t = {}, {}, {}, {}, {} -- vertices (pr_d == false -> triangle), texture
local pr_cx0, pr_cy0, pr_cx1, pr_cy1 = {}, {}, {}, {} -- clip (screen pixels)
@native
local function HashVertex(h1, h2, v)
local p, u, c = v[1], v[2], v[3]
local x, y = p[1], p[2]
local uv = u[1] * 8192 + u[2]
h1 = (h1 * 48271 + x * 4096 + y) % P1
h1 = (h1 * 48271 + uv * 4096) % P1
h1 = (h1 * 48271 + c) % P1
h2 = (h2 * 16807 + y * 4093 + x) % P2
h2 = (h2 * 16807 + uv * 65521) % P2
h2 = (h2 * 16807 + c) % P2
return h1, h2
end
local function GetTile(bd, index, tx, ty)
local tile = bd.Tiles[index]
if tile then return tile end
local img = AssetService:CreateEditableImage({ Size = Vector2.new(TILE, TILE) })
assert(img, "imgui_impl_roblox: EditableImage memory budget exceeded")
local label = Instance.new("ImageLabel")
label.Name = "Tile" .. index
label.BackgroundTransparency = 1
label.BorderSizePixel = 0
local scale = bd.Scale
label.Size = UDim2.fromOffset(TILE / scale, TILE / scale)
label.Position = UDim2.fromOffset(tx * TILE / scale, ty * TILE / scale)
label.ResampleMode = Enum.ResamplerMode.Pixelated
label.ImageContent = Content.fromObject(img)
label.Visible = false
label.Active = bd.TilesActive
label.Parent = bd.Gui
tile = { Image = img, Label = label, Buffer = buffer.create(TILE * TILE * 4), H1 = -1, H2 = -1, Visible = false }
bd.Tiles[index] = tile
return tile
end
local function DestroyTiles(bd)
for _, tile in pairs(bd.Tiles) do tile.Label:Destroy(); tile.Image:Destroy() end
bd.Tiles = {}
end
@native
function ImGui_ImplRoblox_RenderDrawData(draw_data)
local bd = ImGui_ImplRoblox_GetBackendData()
if draw_data.Textures ~= nil then
for _, tex in draw_data.Textures:iter() do
if tex.Status ~= ImTextureStatus.OK then
ImGui_ImplRoblox_UpdateTexture(tex)
bd.ForceRedraw = true -- texture contents changed: tiles sampling it must be redrawn
end
end
end
local sw, sh = floor(draw_data.DisplaySize.x), floor(draw_data.DisplaySize.y)
if sw <= 0 or sh <= 0 then return end
local cols, rows = ceil(sw / TILE), ceil(sh / TILE)
if cols ~= bd.TileCols or rows ~= bd.TileRows then
DestroyTiles(bd)
bd.TileCols, bd.TileRows = cols, rows
end
local ntiles = cols * rows
local ox, oy = draw_data.DisplayPos.x, draw_data.DisplayPos.y
-- Per tile: hashes and the list of primitives touching it
local th1, th2, tn, tl = bd.TH1, bd.TH2, bd.TN, bd.TL
for t = 0, ntiles - 1 do
th1[t], th2[t], tn[t] = 0, 0, 0
if not tl[t] then tl[t] = {} end
end
-- Pass 1: collect primitives, hash them into tiles
local n = 0
for _, draw_list in draw_data.CmdLists:iter() do
local vtx, idx = draw_list.VtxBuffer.Data, draw_list.IdxBuffer.Data
for _, pcmd in draw_list.CmdBuffer:iter() do
if pcmd.UserCallback ~= nil then
pcmd.UserCallback(draw_list, pcmd)
elseif pcmd.ElemCount > 0 then
local clip = pcmd.ClipRect
local cx0, cy0 = max(floor(clip.x - ox), 0), max(floor(clip.y - oy), 0)
local cx1, cy1 = min(floor(clip.z - ox), sw), min(floor(clip.w - oy), sh)
if cx1 > cx0 and cy1 > cy0 then
local tex_id = pcmd:GetTexID()
local t = bd.Textures[tex_id]
local ch1 = ((cx0 * 8191 + cy0) * 8191 + cx1) % P1
local ch2 = ((cy1 * 8191 + cx1) * 8191 + cy0 + tex_id) % P2
local vo = pcmd.VtxOffset
local i, last = pcmd.IdxOffset + 1, pcmd.IdxOffset + pcmd.ElemCount
while i <= last do
local ia, ic = idx[i], idx[i + 2]
local va, vb, vc = vtx[vo + ia], vtx[vo + idx[i + 1]], vtx[vo + ic]
local vd = false
local pa, pb, pc = va[1], vb[1], vc[1]
local bx0, by0, bx1, by1
if i + 5 <= last and idx[i + 3] == ia and idx[i + 4] == ic then
local d = vtx[vo + idx[i + 5]]
local pd = d[1]
-- axis aligned quad (TL, TR, BR, BL) with one colour and a matching uv rect
if pa[2] == pb[2] and pb[1] == pc[1] and pc[2] == pd[2] and pd[1] == pa[1] and pa[1] < pb[1] and pa[2] < pd[2] then
local col = va[3]
local ta, tb, tc, td = va[2], vb[2], vc[2], d[2]
if vb[3] == col and vc[3] == col and d[3] == col
and tb[1] == tc[1] and tb[2] == ta[2] and td[1] == ta[1] and td[2] == tc[2] then
vd = d
bx0, by0 = ceil(pa[1] - ox - 0.5), ceil(pa[2] - oy - 0.5)
bx1, by1 = ceil(pc[1] - ox - 0.5), ceil(pc[2] - oy - 0.5)
end
end
end
if vd then
i = i + 6
else
bx0, by0 = floor(min(pa[1], pb[1], pc[1]) - ox), floor(min(pa[2], pb[2], pc[2]) - oy)
bx1, by1 = ceil(max(pa[1], pb[1], pc[1]) - ox) + 1, ceil(max(pa[2], pb[2], pc[2]) - oy) + 1
i = i + 3
end
if bx0 < cx0 then bx0 = cx0 end
if by0 < cy0 then by0 = cy0 end
if bx1 > cx1 then bx1 = cx1 end
if by1 > cy1 then by1 = cy1 end
if bx0 < bx1 and by0 < by1 then
n = n + 1
pr_a[n], pr_b[n], pr_c[n], pr_d[n], pr_t[n] = va, vb, vc, vd, t
pr_cx0[n], pr_cy0[n], pr_cx1[n], pr_cy1[n] = cx0, cy0, cx1, cy1
local h1, h2 = HashVertex(ch1, ch2, va)
h1, h2 = HashVertex(h1, h2, vb)
h1, h2 = HashVertex(h1, h2, vc)
if vd then h1, h2 = HashVertex(h1, h2, vd) end
for ty = floor(by0 / TILE), floor((by1 - 1) / TILE) do
for tx = floor(bx0 / TILE), floor((bx1 - 1) / TILE) do
local ti = ty * cols + tx
local k = tn[ti] + 1
tn[ti] = k
tl[ti][k] = n
th1[ti] = (th1[ti] * 48271 + h1) % P1
th2[ti] = (th2[ti] * 16807 + h2 + k) % P2
end
end
end
end
end
end
end
end
-- Pass 2: redraw + upload changed tiles
local force = bd.ForceRedraw
bd.ForceRedraw = false
for ty = 0, rows - 1 do
for tx = 0, cols - 1 do
local ti = ty * cols + tx
local count = tn[ti]
local tile = bd.Tiles[ti]
if count == 0 then
if tile and tile.Visible then
tile.Visible = false
tile.Label.Visible = false
tile.H1 = -1
end
else
tile = tile or GetTile(bd, ti, tx, ty)
if force or tile.H1 ~= th1[ti] or tile.H2 ~= th2[ti] then
tile.H1, tile.H2 = th1[ti], th2[ti]
local x0, y0 = tx * TILE, ty * TILE
local x1, y1 = x0 + TILE, y0 + TILE
buf, buf_w = tile.Buffer, TILE
buffer.fill(buf, 0, 0)
local list = tl[ti]
local tox, toy = ox + x0, oy + y0
for k = 1, count do
local p = list[k]
local cx0, cy0 = max(pr_cx0[p], x0) - x0, max(pr_cy0[p], y0) - y0
local cx1, cy1 = min(pr_cx1[p], x1) - x0, min(pr_cy1[p], y1) - y0
local va, vc, vd = pr_a[p], pr_c[p], pr_d[p]
if vd then
local pa, pc, ta, tc = va[1], vc[1], va[2], vc[2]
DrawRect(pa[1] - tox, pa[2] - toy, pc[1] - tox, pc[2] - toy, ta[1], ta[2], tc[1], tc[2], va[3], pr_t[p], cx0, cy0, cx1, cy1)
else
DrawTriangle(va, pr_b[p], vc, pr_t[p], cx0, cy0, cx1, cy1, tox, toy)
end
end
tile.Image:WritePixelsBuffer(Vector2.zero, TILE_SIZE, buf)
end
if not tile.Visible then
tile.Visible = true
tile.Label.Visible = true
end
end
end
end
-- drop references so old vertex tables can be collected
for k = n + 1, bd.LastPrimCount do pr_a[k], pr_b[k], pr_c[k], pr_d[k], pr_t[k] = nil, nil, nil, nil, nil end
bd.LastPrimCount = n
end
---------------------------------------------------------
-- CORE LIFECYCLE
---------------------------------------------------------
--- @param parent Instance? # where the ScreenGui goes, defaults to the local player's PlayerGui
--- @param render_scale number? # imgui pixels per Roblox UI point (defaults to 1). Roblox UI points are scaled by the
--- # OS display scale, so on a 150% display pass 1.5 to render at physical resolution
--- # (imgui then looks the same size as a desktop imgui app). Change later with SetRenderScale().
function ImGui_ImplRoblox_Init(parent, render_scale)
local io = ImGui.GetIO()
local gui = Instance.new("ScreenGui")
gui.Name = "ImGui"
gui.IgnoreGuiInset = true -- so GetMouseLocation() and the tiles share the same origin
gui.ResetOnSpawn = false
gui.DisplayOrder = 1000
gui.Parent = parent or Players.LocalPlayer:WaitForChild("PlayerGui")
local bd = {
Time = os.clock(), Gui = gui, Connections = {},
Textures = {}, TextureCount = 0, MouseX = -1, MouseY = -1,
Tiles = {}, TileCols = 0, TileRows = 0, Scale = render_scale or 1, TilesActive = false, TH1 = {}, TH2 = {}, TN = {}, TL = {}, LastPrimCount = 0, ForceRedraw = true,
}
io.BackendPlatformUserData = bd
io.BackendFlags = bit32.bor(io.BackendFlags, ImGuiBackendFlags.RendererHasTextures, ImGuiBackendFlags.RendererHasVtxOffset)
local platform_io = ImGui.GetPlatformIO()
platform_io.Platform_SetClipboardTextFn = ImGui_ImplRoblox_PlatformSetClipboardText
platform_io.Platform_GetClipboardTextFn = ImGui_ImplRoblox_PlatformGetClipboardText
local screen = gui.AbsoluteSize
ImGui_ImplRoblox_UpdateMonitors(screen.X, screen.Y)
local function connect(signal, fn) table.insert(bd.Connections, signal:Connect(fn)) end
connect(UserInputService.InputBegan, function(input, game_processed)
local io = ImGui.GetIO()
local button = MOUSE_BUTTONS[input.UserInputType]
if button then
io:AddMouseSourceEvent(ImGuiMouseSource.Mouse)
io:AddMouseButtonEvent(button, true)
elseif input.UserInputType == Enum.UserInputType.Keyboard and not game_processed then
local ctrl, shift, alt = ImGui_ImplRoblox_UpdateKeyModifiers()
local key = KEY_MAP[input.KeyCode]
if key then io:AddKeyEvent(key, true) end
-- Text: printable ASCII keys, skipped while Ctrl/Alt are held (shortcuts)
local v = input.KeyCode.Value
if v >= 32 and v < 127 and not (ctrl or alt) then
local c = string.char(v)
if shift then c = SHIFTED[c] or c:upper() end
io:AddInputCharacter(string.byte(c))
end
end
end)
connect(UserInputService.InputEnded, function(input, game_processed)
local io = ImGui.GetIO()
local button = MOUSE_BUTTONS[input.UserInputType]
if button then
io:AddMouseButtonEvent(button, false)
elseif input.UserInputType == Enum.UserInputType.Keyboard then
ImGui_ImplRoblox_UpdateKeyModifiers()
local key = KEY_MAP[input.KeyCode]
if key then io:AddKeyEvent(key, false) end
end
end)
connect(UserInputService.InputChanged, function(input, game_processed)
if input.UserInputType == Enum.UserInputType.MouseWheel then
ImGui.GetIO():AddMouseWheelEvent(0, input.Position.Z)
end
end)
connect(UserInputService.WindowFocused, function() ImGui.GetIO():AddFocusEvent(true) end)
connect(UserInputService.WindowFocusReleased, function() ImGui.GetIO():AddFocusEvent(false) end)
end
function ImGui_ImplRoblox_Shutdown()
local io = ImGui.GetIO()
local bd = ImGui_ImplRoblox_GetBackendData()
for _, c in ipairs(bd.Connections) do c:Disconnect() end
DestroyTiles(bd)
bd.Gui:Destroy()
io.BackendPlatformUserData = nil
io.BackendFlags = bit32.band(io.BackendFlags, bit32.bnot(bit32.bor(
ImGuiBackendFlags.RendererHasTextures,
ImGuiBackendFlags.RendererHasVtxOffset
)))
end
function ImGui_ImplRoblox_NewFrame()
local io = ImGui.GetIO()
local bd = ImGui_ImplRoblox_GetBackendData()
local screen = bd.Gui.AbsoluteSize
local w, h = floor(screen.X * bd.Scale), floor(screen.Y * bd.Scale)
if w ~= bd.ScreenW or h ~= bd.ScreenH then
bd.ScreenW, bd.ScreenH = w, h
ImGui_ImplRoblox_UpdateMonitors(w, h)
end
ImVec2_CopyV(io.DisplaySize, w, h)
local current_time = os.clock()
io.DeltaTime = (current_time > bd.Time) and (current_time - bd.Time) or (1.0 / 60.0)
bd.Time = current_time
local m = UserInputService:GetMouseLocation()
if m.X ~= bd.MouseX or m.Y ~= bd.MouseY then
bd.MouseX, bd.MouseY = m.X, m.Y
io:AddMouseSourceEvent(ImGuiMouseSource.Mouse)
io:AddMousePosEvent(m.X * bd.Scale, m.Y * bd.Scale)
end
-- While the mouse is over imgui, make the tiles Active so Roblox stops passing clicks/wheel to the game (camera zoom etc.)
local want = io.WantCaptureMouse
if want ~= bd.TilesActive then
bd.TilesActive = want
for _, tile in pairs(bd.Tiles) do tile.Label.Active = want end
end
end
function ImGui_ImplRoblox_SetRenderScale(scale)
local bd = ImGui_ImplRoblox_GetBackendData()
if scale == bd.Scale then return end
bd.Scale = scale
DestroyTiles(bd)
bd.TileCols, bd.TileRows = 0, 0
bd.ForceRedraw = true
end
ImGui_ImplRoblox = {
Init = ImGui_ImplRoblox_Init,
Shutdown = ImGui_ImplRoblox_Shutdown,
NewFrame = ImGui_ImplRoblox_NewFrame,
RenderDrawData = ImGui_ImplRoblox_RenderDrawData,
AddFile = ImGui_ImplRoblox_AddFile,
SetRenderScale = ImGui_ImplRoblox_SetRenderScale,
}
return true -- [Roblox] ModuleScripts must return exactly one value