git.sesse.net Git - nageru/blob - theme.lua

   1 -- The theme is what decides what's actually shown on screen, what kind of
   2 -- transitions are available (if any), and what kind of inputs there are,
   3 -- if any. In general, it drives the entire display logic by creating Movit
   4 -- chains, setting their parameters and then deciding which to show when.
   5 --
   6 -- Themes are written in Lua, which reflects a simplified form of the Movit API
   7 -- where all the low-level details (such as texture formats) are handled by the
   8 -- C++ side and you generally just build chains.
   9
  10 local transition_start = -2.0
  11 local transition_end = -1.0
  12 local zoom_src = 0.0
  13 local zoom_dst = 1.0
  14 local zoom_poi = 0   -- which input to zoom in on
  15 local fade_src_signal = 0
  16 local fade_dst_signal = 0
  17
  18 local input0_neutral_color = {0.5, 0.5, 0.5}
  19 local input1_neutral_color = {0.5, 0.5, 0.5}
  20
  21 local live_signal_num = 0
  22 local preview_signal_num = 1
  23
  24 -- Valid values for live_signal_num and preview_signal_num.
  25 local INPUT0_SIGNAL_NUM = 0
  26 local INPUT1_SIGNAL_NUM = 1
  27 local SBS_SIGNAL_NUM = 2
  28 local STATIC_SIGNAL_NUM = 3
  29
  30 -- “fake” signal number that signifies that we are fading from one input
  31 -- to the next.
  32 local FADE_SIGNAL_NUM = 4
  33
  34 -- Last width/height/resolution for each channel, if we have it.
  35 -- Note that unlike the values we get from Nageru, the resolution is per
  36 -- frame and not per field, since we deinterlace.
  37 local last_resolution = {}
  38
  39 -- Utility function to help creating many similar chains that can differ
  40 -- in a free set of chosen parameters.
  41 function make_cartesian_product(parms, callback)
  42         return make_cartesian_product_internal(parms, callback, 1, {})
  43 end
  44
  45 function make_cartesian_product_internal(parms, callback, index, args)
  46         if index > #parms then
  47                 return callback(unpack(args))
  48         end
  49         local ret = {}
  50         for _, value in ipairs(parms[index]) do
  51                 args[index] = value
  52                 ret[value] = make_cartesian_product_internal(parms, callback, index + 1, args)
  53         end
  54         return ret
  55 end
  56
  57 function make_sbs_input(chain, signal, deint, hq)
  58         local input = chain:add_live_input(not deint, deint)  -- Override bounce only if not deinterlacing.
  59         input:connect_signal(signal)
  60         local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
  61
  62         local resample_effect = nil
  63         local resize_effect = nil
  64         if (hq) then
  65                 resample_effect = chain:add_effect(ResampleEffect.new())
  66         else
  67                 resize_effect = chain:add_effect(ResizeEffect.new())
  68         end
  69
  70         local padding_effect = chain:add_effect(IntegralPaddingEffect.new())
  71
  72         return {
  73                 input = input,
  74                 wb_effect = wb_effect,
  75                 resample_effect = resample_effect,
  76                 resize_effect = resize_effect,
  77                 padding_effect = padding_effect
  78         }
  79 end
  80
  81 -- The main live chain.
  82 function make_sbs_chain(input0_deint, input1_deint, hq)
  83         local chain = EffectChain.new(16, 9)
  84
  85         local input0 = make_sbs_input(chain, INPUT0_SIGNAL_NUM, input0_deint, hq)
  86         local input1 = make_sbs_input(chain, INPUT1_SIGNAL_NUM, input1_deint, hq)
  87
  88         input0.padding_effect:set_vec4("border_color", 0.0, 0.0, 0.0, 1.0)
  89         input1.padding_effect:set_vec4("border_color", 0.0, 0.0, 0.0, 0.0)
  90
  91         chain:add_effect(OverlayEffect.new(), input0.padding_effect, input1.padding_effect)
  92         chain:finalize(hq)
  93
  94         return {
  95                 chain = chain,
  96                 input0 = input0,
  97                 input1 = input1
  98         }
  99 end
 100
 101 -- Make all possible combinations of side-by-side chains.
 102 local sbs_chains = make_cartesian_product({
 103         {"live", "livedeint"},  -- input0_type
 104         {"live", "livedeint"},  -- input1_type
 105         {true, false}           -- hq
 106 }, function(input0_type, input1_type, hq)
 107         local input0_deint = (input0_type == "livedeint")
 108         local input1_deint = (input1_type == "livedeint")
 109         return make_sbs_chain(input0_deint, input1_deint, hq)
 110 end)
 111
 112 function make_fade_input(chain, signal, live, deint, scale)
 113         local input, wb_effect, resample_effect, last
 114         if live then
 115                 input = chain:add_live_input(false, deint)
 116                 wb_effect = chain:add_effect(WhiteBalanceEffect.new())
 117                 input:connect_signal(signal)
 118                 last = wb_effect
 119         else
 120                 input = chain:add_effect(ImageInput.new("bg.jpeg"))
 121                 last = input
 122         end
 123
 124         -- If we cared about this for the non-main inputs, we would have
 125         -- checked hq here and invoked ResizeEffect instead.
 126         if scale then
 127                 resample_effect = chain:add_effect(ResampleEffect.new())
 128                 last = resample_effect
 129         end
 130
 131         return {
 132                 input = input,
 133                 wb_effect = wb_effect,
 134                 resample_effect = resample_effect,
 135                 last = last
 136         }
 137 end
 138
 139 -- A chain to fade between two inputs, of which either can be a picture
 140 -- or a live input. In practice only used live, but we still support the
 141 -- hq parameter.
 142 function make_fade_chain(input0_live, input0_deint, input0_scale, input1_live, input1_deint, input1_scale, hq)
 143         local chain = EffectChain.new(16, 9)
 144
 145         local input0 = make_fade_input(chain, INPUT0_SIGNAL_NUM, input0_live, input0_deint, input0_scale)
 146         local input1 = make_fade_input(chain, INPUT1_SIGNAL_NUM, input1_live, input1_deint, input1_scale)
 147
 148         local mix_effect = chain:add_effect(MixEffect.new(), input0.last, input1.last)
 149         chain:finalize(hq)
 150
 151         return {
 152                 chain = chain,
 153                 input0 = input0,
 154                 input1 = input1,
 155                 mix_effect = mix_effect
 156         }
 157 end
 158
 159 -- Chains to fade between two inputs, in various configurations.
 160 local fade_chains = make_cartesian_product({
 161         {"static", "live", "livedeint"},  -- input0_type
 162         {true, false},                    -- input0_scale
 163         {"static", "live", "livedeint"},  -- input1_type
 164         {true, false},                    -- input1_scale
 165         {true}                            -- hq
 166 }, function(input0_type, input0_scale, input1_type, input1_scale, hq)
 167         local input0_live = (input0_type ~= "static")
 168         local input1_live = (input1_type ~= "static")
 169         local input0_deint = (input0_type == "livedeint")
 170         local input1_deint = (input1_type == "livedeint")
 171         return make_fade_chain(input0_live, input0_deint, input0_scale, input1_live, input1_deint, input1_scale, hq)
 172 end)
 173
 174 -- A chain to show a single input on screen.
 175 function make_simple_chain(input_deint, input_scale, hq)
 176         local chain = EffectChain.new(16, 9)
 177
 178         local input = chain:add_live_input(false, input_deint)
 179         input:connect_signal(0)  -- First input card. Can be changed whenever you want.
 180         local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
 181         chain:finalize(hq)
 182
 183         local resample_effect, resize_effect
 184         if scale then
 185                 if hq then
 186                         resample_effect = chain:add_effect(ResampleEffect.new())
 187                 else
 188                         resize_effect = chain:add_effect(ResizeEffect.new())
 189                 end
 190         end
 191
 192         return {
 193                 chain = chain,
 194                 input = input,
 195                 wb_effect = wb_effect,
 196                 resample_effect = resample_effect,
 197                 resize_effect = resize_effect
 198         }
 199 end
 200
 201 -- Make all possible combinations of single-input chains.
 202 local simple_chains = make_cartesian_product({
 203         {"live", "livedeint"},  -- input_type
 204         {true, false},          -- input_scale
 205         {true, false}           -- hq
 206 }, function(input_type, input_scale, hq)
 207         local input_deint = (input_type == "livedeint")
 208         return make_simple_chain(input_deint, input_scale, hq)
 209 end)
 210
 211 -- A chain to show a single static picture on screen (HQ version).
 212 local static_chain_hq = EffectChain.new(16, 9)
 213 local static_chain_hq_input = static_chain_hq:add_effect(ImageInput.new("bg.jpeg"))
 214 static_chain_hq:finalize(true)
 215
 216 -- A chain to show a single static picture on screen (LQ version).
 217 local static_chain_lq = EffectChain.new(16, 9)
 218 local static_chain_lq_input = static_chain_lq:add_effect(ImageInput.new("bg.jpeg"))
 219 static_chain_lq:finalize(false)
 220
 221 -- Used for indexing into the tables of chains.
 222 function get_input_type(signals, signal_num)
 223         if signal_num == STATIC_SIGNAL_NUM then
 224                 return "static"
 225         elseif signals:get_interlaced(signal_num) then
 226                 return "livedeint"
 227         else
 228                 return "live"
 229         end
 230 end
 231
 232 function needs_scale(signals, signal_num, width, height)
 233         if signal_num == STATIC_SIGNAL_NUM then
 234                 -- We assume this is already correctly scaled at load time.
 235                 return false
 236         end
 237         assert(signal_num == INPUT0_SIGNAL_NUM or signal_num == INPUT1_SIGNAL_NUM)
 238         return (signals:get_width(signal_num) ~= width or signals:get_height(signal_num) ~= height)
 239 end
 240
 241 function set_scale_parameters_if_needed(chain_or_input, width, height)
 242         if chain_or_input.resample_effect then
 243                 chain_or_input.resample_effect:set_int("width", width)
 244                 chain_or_input.resample_effect:set_int("height", height)
 245         elseif chain_or_input.resize_effect then
 246                 chain_or_input.resize_effect:set_int("width", width)
 247                 chain_or_input.resize_effect:set_int("height", height)
 248         end
 249 end
 250
 251 -- Returns the number of outputs in addition to the live (0) and preview (1).
 252 -- Called only once, at the start of the program.
 253 function num_channels()
 254         return 4
 255 end
 256
 257 -- Helper function to write e.g. “60” or “59.94”.
 258 function get_frame_rate(signal_num)
 259         local nom = last_resolution[signal_num].frame_rate_nom
 260         local den = last_resolution[signal_num].frame_rate_den
 261         if nom % den == 0 then
 262                 return nom / den
 263         else
 264                 return string.format("%.2f", nom / den)
 265         end
 266 end
 267
 268 -- Helper function to write e.g. “720p60”.
 269 function get_channel_resolution(signal_num)
 270         if last_resolution[signal_num] then
 271                 if last_resolution[signal_num].height == 0 or
 272                    last_resolution[signal_num].height == 525 then
 273                         return "no signal"
 274                 elseif last_resolution[signal_num].interlaced then
 275                         return last_resolution[signal_num].height .. "i" .. get_frame_rate(signal_num)
 276                 else
 277                         return last_resolution[signal_num].height .. "p" .. get_frame_rate(signal_num)
 278                 end
 279         else
 280                 return "no signal"
 281         end
 282 end
 283
 284 -- Returns the name for each additional channel (starting from 2).
 285 -- Called at the start of the program, and then each frame for live
 286 -- channels in case they change resolution.
 287 function channel_name(channel)
 288         if channel == 2 then
 289                 return "Input 1 (" .. get_channel_resolution(0) .. ")"
 290         elseif channel == 3 then
 291                 return "Input 2 (" .. get_channel_resolution(1) .. ")"
 292         elseif channel == 4 then
 293                 return "Side-by-side"
 294         elseif channel == 5 then
 295                 return "Static picture"
 296         end
 297 end
 298
 299 -- Returns if a given channel supports setting white balance (starting from 2).
 300 -- Called only once for each channel, at the start of the program.
 301 function supports_set_wb(channel)
 302         return channel == 2 or channel == 3
 303 end
 304
 305 -- Gets called with a new gray point when the white balance is changing.
 306 -- The color is in linear light (not sRGB gamma).
 307 function set_wb(channel, red, green, blue)
 308         if channel == 2 then
 309                 input0_neutral_color = { red, green, blue }
 310         elseif channel == 3 then
 311                 input1_neutral_color = { red, green, blue }
 312         end
 313 end
 314
 315 function finish_transitions(t)
 316         -- If live is SBS but de-facto single, make it so.
 317         if live_signal_num == SBS_SIGNAL_NUM and t >= transition_end and zoom_dst == 1.0 then
 318                 live_signal_num = zoom_poi
 319         end
 320
 321         -- If live is fade but de-facto single, make it so.
 322         if live_signal_num == FADE_SIGNAL_NUM and t >= transition_end then
 323                 live_signal_num = fade_dst_signal
 324         end
 325 end
 326
 327 -- Called every frame.
 328 function get_transitions(t)
 329         finish_transitions(t)
 330
 331         if live_signal_num == preview_signal_num then
 332                 return {}
 333         end
 334
 335         if live_signal_num == SBS_SIGNAL_NUM and t >= transition_start and t <= transition_end then
 336                 -- Zoom in progress.
 337                 return {"Cut"}
 338         end
 339
 340         if (live_signal_num == INPUT0_SIGNAL_NUM or
 341             live_signal_num == INPUT1_SIGNAL_NUM or
 342             live_signal_num == STATIC_SIGNAL_NUM) and
 343            (preview_signal_num == INPUT0_SIGNAL_NUM or
 344             preview_signal_num == INPUT1_SIGNAL_NUM or
 345             preview_signal_num == STATIC_SIGNAL_NUM) then
 346                 return {"Cut", "", "Fade"}
 347         end
 348
 349         -- Various zooms.
 350         if live_signal_num == SBS_SIGNAL_NUM and
 351            (preview_signal_num == INPUT0_SIGNAL_NUM or preview_signal_num == INPUT1_SIGNAL_NUM) then
 352                 return {"Cut", "Zoom in"}
 353         elseif (live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM) and
 354                preview_signal_num == SBS_SIGNAL_NUM then
 355                 return {"Cut", "Zoom out"}
 356         end
 357
 358         return {"Cut"}
 359 end
 360
 361 function transition_clicked(num, t)
 362         if num == 0 then
 363                 -- Cut.
 364                 if live_signal_num == FADE_SIGNAL_NUM then
 365                         -- Ongoing fade; finish it immediately.
 366                         finish_transitions(transition_end)
 367                 end
 368
 369                 local temp = live_signal_num
 370                 live_signal_num = preview_signal_num
 371                 preview_signal_num = temp
 372
 373                 if live_signal_num == SBS_SIGNAL_NUM then
 374                         -- Just cut to SBS, we need to reset any zooms.
 375                         zoom_src = 1.0
 376                         zoom_dst = 0.0
 377                         transition_start = -2.0
 378                         transition_end = -1.0
 379                 end
 380         elseif num == 1 then
 381                 -- Zoom.
 382
 383                 finish_transitions(t)
 384
 385                 if live_signal_num == preview_signal_num then
 386                         -- Nothing to do.
 387                         return
 388                 end
 389
 390                 if (live_signal_num == INPUT0_SIGNAL_NUM and preview_signal_num == INPUT1_SIGNAL_NUM) or
 391                    (live_signal_num == INPUT1_SIGNAL_NUM and preview_signal_num == INPUT0_SIGNAL_NUM) then
 392                         -- We can't zoom between these. Just make a cut.
 393                         io.write("Cutting from " .. live_signal_num .. " to " .. live_signal_num .. "\n")
 394                         local temp = live_signal_num
 395                         live_signal_num = preview_signal_num
 396                         preview_signal_num = temp
 397                         return
 398                 end
 399
 400                 if live_signal_num == SBS_SIGNAL_NUM and
 401                    (preview_signal_num == INPUT0_SIGNAL_NUM or preview_signal_num == INPUT1_SIGNAL_NUM) then
 402                         -- Zoom in from SBS to single.
 403                         transition_start = t
 404                         transition_end = t + 1.0
 405                         zoom_src = 0.0
 406                         zoom_dst = 1.0
 407                         zoom_poi = preview_signal_num
 408                         preview_signal_num = SBS_SIGNAL_NUM
 409                 elseif (live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM) and
 410                        preview_signal_num == SBS_SIGNAL_NUM then
 411                         -- Zoom out from single to SBS.
 412                         transition_start = t
 413                         transition_end = t + 1.0
 414                         zoom_src = 1.0
 415                         zoom_dst = 0.0
 416                         preview_signal_num = live_signal_num
 417                         zoom_poi = live_signal_num
 418                         live_signal_num = SBS_SIGNAL_NUM
 419                 end
 420         elseif num == 2 then
 421                 finish_transitions(t)
 422
 423                 -- Fade.
 424                 if (live_signal_num ~= preview_signal_num) and
 425                    (live_signal_num == INPUT0_SIGNAL_NUM or
 426                     live_signal_num == INPUT1_SIGNAL_NUM or
 427                     live_signal_num == STATIC_SIGNAL_NUM) and
 428                    (preview_signal_num == INPUT0_SIGNAL_NUM or
 429                     preview_signal_num == INPUT1_SIGNAL_NUM or
 430                     preview_signal_num == STATIC_SIGNAL_NUM) then
 431                         transition_start = t
 432                         transition_end = t + 1.0
 433                         fade_src_signal = live_signal_num
 434                         fade_dst_signal = preview_signal_num
 435                         preview_signal_num = live_signal_num
 436                         live_signal_num = FADE_SIGNAL_NUM
 437                 else
 438                         -- Fades involving SBS are ignored (we have no chain for it).
 439                 end
 440         end
 441 end
 442
 443 function channel_clicked(num)
 444         preview_signal_num = num
 445 end
 446
 447 -- Called every frame. Get the chain for displaying at input <num>,
 448 -- where 0 is live, 1 is preview, 2 is the first channel to display
 449 -- in the bottom bar, and so on up to num_channels()+1. t is the
 450 -- current time in seconds. width and height are the dimensions of
 451 -- the output, although you can ignore them if you don't need them
 452 -- (they're useful if you want to e.g. know what to resample by).
 453 --
 454 -- <signals> is basically an exposed InputState, which you can use to
 455 -- query for information about the signals at the point of the current
 456 -- frame. In particular, you can call get_width() and get_height()
 457 -- for any signal number, and use that to e.g. assist in chain selection.
 458 --
 459 -- You should return two objects; the chain itself, and then a
 460 -- function (taking no parameters) that is run just before rendering.
 461 -- The function needs to call connect_signal on any inputs, so that
 462 -- it gets updated video data for the given frame. (You are allowed
 463 -- to switch which input your input is getting from between frames,
 464 -- but not calling connect_signal results in undefined behavior.)
 465 -- If you want to change any parameters in the chain, this is also
 466 -- the right place.
 467 --
 468 -- NOTE: The chain returned must be finalized with the Y'CbCr flag
 469 -- if and only if num==0.
 470 function get_chain(num, t, width, height, signals)
 471         local input_resolution = {}
 472         for signal_num=0,1 do
 473                 local res = {
 474                         width = signals:get_width(signal_num),
 475                         height = signals:get_height(signal_num),
 476                         interlaced = signals:get_interlaced(signal_num),
 477                         frame_rate_nom = signals:get_frame_rate_nom(signal_num),
 478                         frame_rate_den = signals:get_frame_rate_den(signal_num)
 479                 }
 480
 481                 if res.interlaced then
 482                         -- Convert height from frame height to field height.
 483                         -- (Needed for e.g. place_rectangle.)
 484                         res.height = res.height * 2
 485
 486                         -- Show field rate instead of frame rate; really for cosmetics only
 487                         -- (and actually contrary to EBU recommendations, although in line
 488                         -- with typical user expectations).
 489                         res.frame_rate_nom = res.frame_rate_nom * 2
 490                 end
 491
 492                 input_resolution[signal_num] = res
 493         end
 494         last_resolution = input_resolution
 495
 496         if num == 0 then  -- Live.
 497                 if live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM then  -- Plain input.
 498                         local input_type = get_input_type(signals, live_signal_num)
 499                         local input_scale = needs_scale(signals, live_signal_num, width, height)
 500                         local chain = simple_chains[input_type][input_scale][true]
 501                         prepare = function()
 502                                 chain.input:connect_signal(live_signal_num)
 503                                 set_scale_parameters_if_needed(chain, width, height)
 504                                 set_neutral_color_from_signal(chain.wb_effect, live_signal_num)
 505                         end
 506                         return chain.chain, prepare
 507                 elseif live_signal_num == STATIC_SIGNAL_NUM then  -- Static picture.
 508                         prepare = function()
 509                         end
 510                         return static_chain_hq, prepare
 511                 elseif live_signal_num == FADE_SIGNAL_NUM then  -- Fade.
 512                         local input0_type = get_input_type(signals, fade_src_signal)
 513                         local input0_scale = needs_scale(signals, fade_src_signal, width, height)
 514                         local input1_type = get_input_type(signals, fade_dst_signal)
 515                         local input1_scale = needs_scale(signals, fade_dst_signal, width, height)
 516                         local chain = fade_chains[input0_type][input0_scale][input1_type][input1_scale][true]
 517                         prepare = function()
 518                                 if input0_type == "live" then
 519                                         chain.input0.input:connect_signal(fade_src_signal)
 520                                         set_neutral_color_from_signal(chain.input0.wb_effect, fade_src_signal)
 521                                 end
 522                                 set_scale_parameters_if_needed(chain.input0, width, height)
 523                                 if input1_type == "live" then
 524                                         chain.input1.input:connect_signal(fade_dst_signal)
 525                                         set_neutral_color_from_signal(chain.input1.wb_effect, fade_dst_signal)
 526                                 end
 527                                 set_scale_parameters_if_needed(chain.input1, width, height)
 528                                 local tt = calc_fade_progress(t, transition_start, transition_end)
 529
 530                                 chain.mix_effect:set_float("strength_first", 1.0 - tt)
 531                                 chain.mix_effect:set_float("strength_second", tt)
 532                         end
 533                         return chain.chain, prepare
 534                 end
 535
 536                 -- SBS code (live_signal_num == SBS_SIGNAL_NUM).
 537                 local input0_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
 538                 local input1_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
 539                 if t > transition_end and zoom_dst == 1.0 then
 540                         -- Special case: Show only the single image on screen.
 541                         local input0_scale = needs_scale(signals, fade_src_signal, width, height)
 542                         local chain = simple_chains[input0_type][input0_scale][true]
 543                         prepare = function()
 544                                 chain.input:connect_signal(INPUT0_SIGNAL_NUM)
 545                                 set_scale_parameters_if_needed(chain, width, height)
 546                                 set_neutral_color(chain.wb_effect, input0_neutral_color)
 547                         end
 548                         return chain.chain, prepare
 549                 end
 550                 local chain = sbs_chains[input0_type][input1_type][true]
 551                 prepare = function()
 552                         if t < transition_start then
 553                                 prepare_sbs_chain(chain, zoom_src, width, height, input_resolution)
 554                         elseif t > transition_end then
 555                                 prepare_sbs_chain(chain, zoom_dst, width, height, input_resolution)
 556                         else
 557                                 local tt = (t - transition_start) / (transition_end - transition_start)
 558                                 -- Smooth it a bit.
 559                                 tt = math.sin(tt * 3.14159265358 * 0.5)
 560                                 prepare_sbs_chain(chain, zoom_src + (zoom_dst - zoom_src) * tt, width, height, input_resolution)
 561                         end
 562                 end
 563                 return chain.chain, prepare
 564         end
 565         if num == 1 then  -- Preview.
 566                 num = preview_signal_num + 2
 567         end
 568
 569         -- Individual preview inputs.
 570         if num == INPUT0_SIGNAL_NUM + 2 then
 571                 local input_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
 572                 local input_scale = needs_scale(signals, INPUT0_SIGNAL_NUM, width, height)
 573                 local chain = simple_chains[input_type][input_scale][false]
 574                 prepare = function()
 575                         chain.input:connect_signal(INPUT0_SIGNAL_NUM)
 576                         set_scale_parameters_if_needed(chain, width, height)
 577                         set_neutral_color(chain.wb_effect, input0_neutral_color)
 578                 end
 579                 return chain.chain, prepare
 580         end
 581         if num == INPUT1_SIGNAL_NUM + 2 then
 582                 local input_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
 583                 local input_scale = needs_scale(signals, INPUT1_SIGNAL_NUM, width, height)
 584                 local chain = simple_chains[input_type][input_scale][false]
 585                 prepare = function()
 586                         chain.input:connect_signal(INPUT1_SIGNAL_NUM)
 587                         set_scale_parameters_if_needed(chain, width, height)
 588                         set_neutral_color(chain.wb_effect, input1_neutral_color)
 589                 end
 590                 return chain.chain, prepare
 591         end
 592         if num == SBS_SIGNAL_NUM + 2 then
 593                 local input0_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
 594                 local input1_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
 595                 local chain = sbs_chains[input0_type][input1_type][false]
 596                 prepare = function()
 597                         prepare_sbs_chain(chain, 0.0, width, height, input_resolution)
 598                 end
 599                 return chain.chain, prepare
 600         end
 601         if num == STATIC_SIGNAL_NUM + 2 then
 602                 prepare = function()
 603                 end
 604                 return static_chain_lq, prepare
 605         end
 606 end
 607
 608 function place_rectangle(resample_effect, resize_effect, padding_effect, x0, y0, x1, y1, screen_width, screen_height, input_width, input_height)
 609         local srcx0 = 0.0
 610         local srcx1 = 1.0
 611         local srcy0 = 0.0
 612         local srcy1 = 1.0
 613
 614         -- Cull.
 615         if x0 > screen_width or x1 < 0.0 or y0 > screen_height or y1 < 0.0 then
 616                 resample_effect:set_int("width", 1)
 617                 resample_effect:set_int("height", 1)
 618                 resample_effect:set_float("zoom_x", screen_width)
 619                 resample_effect:set_float("zoom_y", screen_height)
 620                 padding_effect:set_int("left", screen_width + 100)
 621                 padding_effect:set_int("top", screen_height + 100)
 622                 return
 623         end
 624
 625         -- Clip.
 626         if x0 < 0 then
 627                 srcx0 = -x0 / (x1 - x0)
 628                 x0 = 0
 629         end
 630         if y0 < 0 then
 631                 srcy0 = -y0 / (y1 - y0)
 632                 y0 = 0
 633         end
 634         if x1 > screen_width then
 635                 srcx1 = (screen_width - x0) / (x1 - x0)
 636                 x1 = screen_width
 637         end
 638         if y1 > screen_height then
 639                 srcy1 = (screen_height - y0) / (y1 - y0)
 640                 y1 = screen_height
 641         end
 642
 643         if resample_effect ~= nil then
 644                 -- High-quality resampling.
 645                 local x_subpixel_offset = x0 - math.floor(x0)
 646                 local y_subpixel_offset = y0 - math.floor(y0)
 647
 648                 -- Resampling must be to an integral number of pixels. Round up,
 649                 -- and then add an extra pixel so we have some leeway for the border.
 650                 local width = math.ceil(x1 - x0) + 1
 651                 local height = math.ceil(y1 - y0) + 1
 652                 resample_effect:set_int("width", width)
 653                 resample_effect:set_int("height", height)
 654
 655                 -- Correct the discrepancy with zoom. (This will leave a small
 656                 -- excess edge of pixels and subpixels, which we'll correct for soon.)
 657                 local zoom_x = (x1 - x0) / (width * (srcx1 - srcx0))
 658                 local zoom_y = (y1 - y0) / (height * (srcy1 - srcy0))
 659                 resample_effect:set_float("zoom_x", zoom_x)
 660                 resample_effect:set_float("zoom_y", zoom_y)
 661                 resample_effect:set_float("zoom_center_x", 0.0)
 662                 resample_effect:set_float("zoom_center_y", 0.0)
 663
 664                 -- Padding must also be to a whole-pixel offset.
 665                 padding_effect:set_int("left", math.floor(x0))
 666                 padding_effect:set_int("top", math.floor(y0))
 667
 668                 -- Correct _that_ discrepancy by subpixel offset in the resampling.
 669                 resample_effect:set_float("left", srcx0 * input_width - x_subpixel_offset / zoom_x)
 670                 resample_effect:set_float("top", srcy0 * input_height - y_subpixel_offset / zoom_y)
 671
 672                 -- Finally, adjust the border so it is exactly where we want it.
 673                 padding_effect:set_float("border_offset_left", x_subpixel_offset)
 674                 padding_effect:set_float("border_offset_right", x1 - (math.floor(x0) + width))
 675                 padding_effect:set_float("border_offset_top", y_subpixel_offset)
 676                 padding_effect:set_float("border_offset_bottom", y1 - (math.floor(y0) + height))
 677         else
 678                 -- Lower-quality simple resizing.
 679                 local width = round(x1 - x0)
 680                 local height = round(y1 - y0)
 681                 resize_effect:set_int("width", width)
 682                 resize_effect:set_int("height", height)
 683
 684                 -- Padding must also be to a whole-pixel offset.
 685                 padding_effect:set_int("left", math.floor(x0))
 686                 padding_effect:set_int("top", math.floor(y0))
 687         end
 688 end
 689
 690 -- This is broken, of course (even for positive numbers), but Lua doesn't give us access to real rounding.
 691 function round(x)
 692         return math.floor(x + 0.5)
 693 end
 694
 695 function lerp(a, b, t)
 696         return a + (b - a) * t
 697 end
 698
 699 function prepare_sbs_chain(chain, t, screen_width, screen_height, input_resolution)
 700         chain.input0.input:connect_signal(0)
 701         chain.input1.input:connect_signal(1)
 702         set_neutral_color(chain.input0.wb_effect, input0_neutral_color)
 703         set_neutral_color(chain.input1.wb_effect, input1_neutral_color)
 704
 705         -- First input is positioned (16,48) from top-left.
 706         local width0 = round(848 * screen_width/1280.0)
 707         local height0 = round(width0 * 9.0 / 16.0)
 708
 709         local top0 = 48 * screen_height/720.0
 710         local left0 = 16 * screen_width/1280.0
 711         local bottom0 = top0 + height0
 712         local right0 = left0 + width0
 713
 714         -- Second input is positioned (16,48) from the bottom-right.
 715         local width1 = round(384 * screen_width/1280.0)
 716         local height1 = round(216 * screen_height/720.0)
 717
 718         local bottom1 = screen_height - 48 * screen_height/720.0
 719         local right1 = screen_width - 16 * screen_width/1280.0
 720         local top1 = bottom1 - height1
 721         local left1 = right1 - width1
 722
 723         -- Interpolate between the fullscreen and side-by-side views.
 724         local scale0, tx0, tx0
 725         if zoom_poi == INPUT0_SIGNAL_NUM then
 726                 local new_left0 = lerp(left0, 0, t)
 727                 local new_right0 = lerp(right0, screen_width, t)
 728                 local new_top0 = lerp(top0, 0, t)
 729                 local new_bottom0 = lerp(bottom0, screen_height, t)
 730
 731                 scale0 = (new_right0 - new_left0) / width0  -- Same vertically and horizonally.
 732                 tx0 = new_left0 - left0 * scale0
 733                 ty0 = new_top0 - top0 * scale0
 734         else
 735                 local new_left1 = lerp(left1, 0, t)
 736                 local new_right1 = lerp(right1, screen_width, t)
 737                 local new_top1 = lerp(top1, 0, t)
 738                 local new_bottom1 = lerp(bottom1, screen_height, t)
 739
 740                 scale0 = (new_right1 - new_left1) / width1  -- Same vertically and horizonally.
 741                 tx0 = new_left1 - left1 * scale0
 742                 ty0 = new_top1 - top1 * scale0
 743         end
 744
 745         top0 = top0 * scale0 + ty0
 746         bottom0 = bottom0 * scale0 + ty0
 747         left0 = left0 * scale0 + tx0
 748         right0 = right0 * scale0 + tx0
 749
 750         top1 = top1 * scale0 + ty0
 751         bottom1 = bottom1 * scale0 + ty0
 752         left1 = left1 * scale0 + tx0
 753         right1 = right1 * scale0 + tx0
 754         place_rectangle(chain.input0.resample_effect, chain.input0.resize_effect, chain.input0.padding_effect, left0, top0, right0, bottom0, screen_width, screen_height, input_resolution[0].width, input_resolution[0].height)
 755         place_rectangle(chain.input1.resample_effect, chain.input1.resize_effect, chain.input1.padding_effect, left1, top1, right1, bottom1, screen_width, screen_height, input_resolution[1].width, input_resolution[1].height)
 756 end
 757
 758 function set_neutral_color(effect, color)
 759         effect:set_vec3("neutral_color", color[1], color[2], color[3])
 760 end
 761
 762 function set_neutral_color_from_signal(effect, signal)
 763         if signal == INPUT0_SIGNAL_NUM then
 764                 set_neutral_color(effect, input0_neutral_color)
 765         else
 766                 set_neutral_color(effect, input1_neutral_color)
 767         end
 768 end
 769
 770 function calc_fade_progress(t, transition_start, transition_end)
 771         local tt = (t - transition_start) / (transition_end - transition_start)
 772         if tt < 0.0 then
 773                 tt = 0.0
 774         elseif tt > 1.0 then
 775                 tt = 1.0
 776         end
 777
 778         -- Make the fade look maybe a tad more natural, by pumping it
 779         -- through a sigmoid function.
 780         tt = 10.0 * tt - 5.0
 781         tt = 1.0 / (1.0 + math.exp(-tt))
 782
 783         return tt
 784 end