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 -- Utility function to help creating many similar chains that can differ
  35 -- in a free set of chosen parameters.
  36 function make_cartesian_product(parms, callback)
  37         return make_cartesian_product_internal(parms, callback, 1, {})
  38 end
  39
  40 function make_cartesian_product_internal(parms, callback, index, args)
  41         if index > #parms then
  42                 return callback(unpack(args))
  43         end
  44         local ret = {}
  45         for _, value in ipairs(parms[index]) do
  46                 args[index] = value
  47                 ret[value] = make_cartesian_product_internal(parms, callback, index + 1, args)
  48         end
  49         return ret
  50 end
  51
  52 function make_sbs_input(chain, signal, deint, hq)
  53         local input = chain:add_live_input(not deint, deint)  -- Override bounce only if not deinterlacing.
  54         input:connect_signal(signal)
  55         local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
  56
  57         local resample_effect = nil
  58         local resize_effect = nil
  59         if (hq) then
  60                 resample_effect = chain:add_effect(ResampleEffect.new())
  61         else
  62                 resize_effect = chain:add_effect(ResizeEffect.new())
  63         end
  64
  65         local padding_effect = chain:add_effect(IntegralPaddingEffect.new())
  66
  67         return {
  68                 input = input,
  69                 wb_effect = wb_effect,
  70                 resample_effect = resample_effect,
  71                 resize_effect = resize_effect,
  72                 padding_effect = padding_effect
  73         }
  74 end
  75
  76 -- The main live chain.
  77 function make_sbs_chain(input0_deint, input1_deint, hq)
  78         local chain = EffectChain.new(16, 9)
  79
  80         local input0 = make_sbs_input(chain, INPUT0_SIGNAL_NUM, input0_deint, hq)
  81         local input1 = make_sbs_input(chain, INPUT1_SIGNAL_NUM, input1_deint, hq)
  82
  83         input0.padding_effect:set_vec4("border_color", 0.0, 0.0, 0.0, 1.0)
  84         input1.padding_effect:set_vec4("border_color", 0.0, 0.0, 0.0, 0.0)
  85
  86         chain:add_effect(OverlayEffect.new(), input0.padding_effect, input1.padding_effect)
  87         chain:finalize(hq)
  88
  89         return {
  90                 chain = chain,
  91                 input0 = input0,
  92                 input1 = input1
  93         }
  94 end
  95
  96 -- Make all possible combinations of side-by-side chains.
  97 local sbs_chains = make_cartesian_product({
  98         {"live", "livedeint"},  -- input0_type
  99         {"live", "livedeint"},  -- input1_type
 100         {true, false}           -- hq
 101 }, function(input0_type, input1_type, hq)
 102         local input0_deint = (input0_type == "livedeint")
 103         local input1_deint = (input1_type == "livedeint")
 104         return make_sbs_chain(input0_deint, input1_deint, hq)
 105 end)
 106
 107 function make_fade_input(chain, signal, live, deint, scale)
 108         local input, wb_effect, resample_effect, last
 109         if live then
 110                 input = chain:add_live_input(false, deint)
 111                 wb_effect = chain:add_effect(WhiteBalanceEffect.new())
 112                 input:connect_signal(signal)
 113                 last = wb_effect
 114         else
 115                 input = chain:add_effect(ImageInput.new("bg.jpeg"))
 116                 last = input
 117         end
 118
 119         -- If we cared about this for the non-main inputs, we would have
 120         -- checked hq here and invoked ResizeEffect instead.
 121         if scale then
 122                 resample_effect = chain:add_effect(ResampleEffect.new())
 123                 last = resample_effect
 124         end
 125
 126         return {
 127                 input = input,
 128                 wb_effect = wb_effect,
 129                 resample_effect = resample_effect,
 130                 last = last
 131         }
 132 end
 133
 134 -- A chain to fade between two inputs, of which either can be a picture
 135 -- or a live input. In practice only used live, but we still support the
 136 -- hq parameter.
 137 function make_fade_chain(input0_live, input0_deint, input0_scale, input1_live, input1_deint, input1_scale, hq)
 138         local chain = EffectChain.new(16, 9)
 139
 140         local input0 = make_fade_input(chain, INPUT0_SIGNAL_NUM, input0_live, input0_deint, input0_scale)
 141         local input1 = make_fade_input(chain, INPUT1_SIGNAL_NUM, input1_live, input1_deint, input1_scale)
 142
 143         local mix_effect = chain:add_effect(MixEffect.new(), input0.last, input1.last)
 144         chain:finalize(hq)
 145
 146         return {
 147                 chain = chain,
 148                 input0 = input0,
 149                 input1 = input1,
 150                 mix_effect = mix_effect
 151         }
 152 end
 153
 154 -- Chains to fade between two inputs, in various configurations.
 155 local fade_chains = make_cartesian_product({
 156         {"static", "live", "livedeint"},  -- input0_type
 157         {true, false},                    -- input0_scale
 158         {"static", "live", "livedeint"},  -- input1_type
 159         {true, false},                    -- input1_scale
 160         {true}                            -- hq
 161 }, function(input0_type, input0_scale, input1_type, input1_scale, hq)
 162         local input0_live = (input0_type ~= "static")
 163         local input1_live = (input1_type ~= "static")
 164         local input0_deint = (input0_type == "livedeint")
 165         local input1_deint = (input1_type == "livedeint")
 166         return make_fade_chain(input0_live, input0_deint, input0_scale, input1_live, input1_deint, input1_scale, hq)
 167 end)
 168
 169 -- A chain to show a single input on screen.
 170 function make_simple_chain(input_deint, input_scale, hq)
 171         local chain = EffectChain.new(16, 9)
 172
 173         local input = chain:add_live_input(false, input_deint)
 174         input:connect_signal(0)  -- First input card. Can be changed whenever you want.
 175         local wb_effect = chain:add_effect(WhiteBalanceEffect.new())
 176         chain:finalize(hq)
 177
 178         local resample_effect, resize_effect
 179         if scale then
 180                 if hq then
 181                         resample_effect = chain:add_effect(ResampleEffect.new())
 182                 else
 183                         resize_effect = chain:add_effect(ResizeEffect.new())
 184                 end
 185         end
 186
 187         return {
 188                 chain = chain,
 189                 input = input,
 190                 wb_effect = wb_effect,
 191                 resample_effect = resample_effect,
 192                 resize_effect = resize_effect
 193         }
 194 end
 195
 196 -- Make all possible combinations of single-input chains.
 197 local simple_chains = make_cartesian_product({
 198         {"live", "livedeint"},  -- input_type
 199         {true, false},          -- input_scale
 200         {true, false}           -- hq
 201 }, function(input_type, input_scale, hq)
 202         local input_deint = (input_type == "livedeint")
 203         return make_simple_chain(input_deint, input_scale, hq)
 204 end)
 205
 206 -- A chain to show a single static picture on screen (HQ version).
 207 local static_chain_hq = EffectChain.new(16, 9)
 208 local static_chain_hq_input = static_chain_hq:add_effect(ImageInput.new("bg.jpeg"))
 209 static_chain_hq:finalize(true)
 210
 211 -- A chain to show a single static picture on screen (LQ version).
 212 local static_chain_lq = EffectChain.new(16, 9)
 213 local static_chain_lq_input = static_chain_lq:add_effect(ImageInput.new("bg.jpeg"))
 214 static_chain_lq:finalize(false)
 215
 216 -- Used for indexing into the tables of chains.
 217 function get_input_type(signals, signal_num)
 218         if signal_num == STATIC_SIGNAL_NUM then
 219                 return "static"
 220         elseif signals:get_interlaced(signal_num) then
 221                 return "livedeint"
 222         else
 223                 return "live"
 224         end
 225 end
 226
 227 function needs_scale(signals, signal_num, width, height)
 228         return (signals:get_width(signal_num) ~= width or signals:get_height(signal_num) ~= height)
 229 end
 230
 231 function set_scale_parameters_if_needed(chain_or_input, width, height)
 232         if chain_or_input.resample_effect then
 233                 chain_or_input.resample_effect:set_int("width", width)
 234                 chain_or_input.resample_effect:set_int("height", height)
 235         elseif chain_or_input.resize_effect then
 236                 chain_or_input.resize_effect:set_int("width", width)
 237                 chain_or_input.resize_effect:set_int("height", height)
 238         end
 239 end
 240
 241 -- Returns the number of outputs in addition to the live (0) and preview (1).
 242 -- Called only once, at the start of the program.
 243 function num_channels()
 244         return 4
 245 end
 246
 247 -- Returns the name for each additional channel (starting from 2).
 248 -- Called only once for each channel, at the start of the program.
 249 function channel_name(channel)
 250         if channel == 2 then
 251                 return "Input 1"
 252         elseif channel == 3 then
 253                 return "Input 2"
 254         elseif channel == 4 then
 255                 return "Side-by-side"
 256         elseif channel == 5 then
 257                 return "Static picture"
 258         end
 259 end
 260
 261 -- Returns if a given channel supports setting white balance (starting from 2).
 262 -- Called only once for each channel, at the start of the program.
 263 function supports_set_wb(channel)
 264         return channel == 2 or channel == 3
 265 end
 266
 267 -- Gets called with a new gray point when the white balance is changing.
 268 -- The color is in linear light (not sRGB gamma).
 269 function set_wb(channel, red, green, blue)
 270         if channel == 2 then
 271                 input0_neutral_color = { red, green, blue }
 272         elseif channel == 3 then
 273                 input1_neutral_color = { red, green, blue }
 274         end
 275 end
 276
 277 function finish_transitions(t)
 278         -- If live is SBS but de-facto single, make it so.
 279         if live_signal_num == SBS_SIGNAL_NUM and t >= transition_end and zoom_dst == 1.0 then
 280                 live_signal_num = zoom_poi
 281         end
 282
 283         -- If live is fade but de-facto single, make it so.
 284         if live_signal_num == FADE_SIGNAL_NUM and t >= transition_end then
 285                 live_signal_num = fade_dst_signal
 286         end
 287 end
 288
 289 -- Called every frame.
 290 function get_transitions(t)
 291         finish_transitions(t)
 292
 293         if live_signal_num == preview_signal_num then
 294                 return {}
 295         end
 296
 297         if live_signal_num == SBS_SIGNAL_NUM and t >= transition_start and t <= transition_end then
 298                 -- Zoom in progress.
 299                 return {"Cut"}
 300         end
 301
 302         if (live_signal_num == INPUT0_SIGNAL_NUM or
 303             live_signal_num == INPUT1_SIGNAL_NUM or
 304             live_signal_num == STATIC_SIGNAL_NUM) and
 305            (preview_signal_num == INPUT0_SIGNAL_NUM or
 306             preview_signal_num == INPUT1_SIGNAL_NUM or
 307             preview_signal_num == STATIC_SIGNAL_NUM) then
 308                 return {"Cut", "", "Fade"}
 309         end
 310
 311         -- Various zooms.
 312         if live_signal_num == SBS_SIGNAL_NUM and
 313            (preview_signal_num == INPUT0_SIGNAL_NUM or preview_signal_num == INPUT1_SIGNAL_NUM) then
 314                 return {"Cut", "Zoom in"}
 315         elseif (live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM) and
 316                preview_signal_num == SBS_SIGNAL_NUM then
 317                 return {"Cut", "Zoom out"}
 318         end
 319
 320         return {"Cut"}
 321 end
 322
 323 function transition_clicked(num, t)
 324         if num == 0 then
 325                 -- Cut.
 326                 if live_signal_num == FADE_SIGNAL_NUM then
 327                         -- Ongoing fade; finish it immediately.
 328                         finish_transitions(transition_end)
 329                 end
 330
 331                 local temp = live_signal_num
 332                 live_signal_num = preview_signal_num
 333                 preview_signal_num = temp
 334
 335                 if live_signal_num == SBS_SIGNAL_NUM then
 336                         -- Just cut to SBS, we need to reset any zooms.
 337                         zoom_src = 1.0
 338                         zoom_dst = 0.0
 339                         transition_start = -2.0
 340                         transition_end = -1.0
 341                 end
 342         elseif num == 1 then
 343                 -- Zoom.
 344
 345                 finish_transitions(t)
 346
 347                 if live_signal_num == preview_signal_num then
 348                         -- Nothing to do.
 349                         return
 350                 end
 351
 352                 if (live_signal_num == INPUT0_SIGNAL_NUM and preview_signal_num == INPUT1_SIGNAL_NUM) or
 353                    (live_signal_num == INPUT1_SIGNAL_NUM and preview_signal_num == INPUT0_SIGNAL_NUM) then
 354                         -- We can't zoom between these. Just make a cut.
 355                         io.write("Cutting from " .. live_signal_num .. " to " .. live_signal_num .. "\n")
 356                         local temp = live_signal_num
 357                         live_signal_num = preview_signal_num
 358                         preview_signal_num = temp
 359                         return
 360                 end
 361
 362                 if live_signal_num == SBS_SIGNAL_NUM and
 363                    (preview_signal_num == INPUT0_SIGNAL_NUM or preview_signal_num == INPUT1_SIGNAL_NUM) then
 364                         -- Zoom in from SBS to single.
 365                         transition_start = t
 366                         transition_end = t + 1.0
 367                         zoom_src = 0.0
 368                         zoom_dst = 1.0
 369                         zoom_poi = preview_signal_num
 370                         preview_signal_num = SBS_SIGNAL_NUM
 371                 elseif (live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM) and
 372                        preview_signal_num == SBS_SIGNAL_NUM then
 373                         -- Zoom out from single to SBS.
 374                         transition_start = t
 375                         transition_end = t + 1.0
 376                         zoom_src = 1.0
 377                         zoom_dst = 0.0
 378                         preview_signal_num = live_signal_num
 379                         zoom_poi = live_signal_num
 380                         live_signal_num = SBS_SIGNAL_NUM
 381                 end
 382         elseif num == 2 then
 383                 finish_transitions(t)
 384
 385                 -- Fade.
 386                 if (live_signal_num ~= preview_signal_num) and
 387                    (live_signal_num == INPUT0_SIGNAL_NUM or
 388                     live_signal_num == INPUT1_SIGNAL_NUM or
 389                     live_signal_num == STATIC_SIGNAL_NUM) and
 390                    (preview_signal_num == INPUT0_SIGNAL_NUM or
 391                     preview_signal_num == INPUT1_SIGNAL_NUM or
 392                     preview_signal_num == STATIC_SIGNAL_NUM) then
 393                         transition_start = t
 394                         transition_end = t + 1.0
 395                         fade_src_signal = live_signal_num
 396                         fade_dst_signal = preview_signal_num
 397                         preview_signal_num = live_signal_num
 398                         live_signal_num = FADE_SIGNAL_NUM
 399                 else
 400                         -- Fades involving SBS are ignored (we have no chain for it).
 401                 end
 402         end
 403 end
 404
 405 function channel_clicked(num)
 406         preview_signal_num = num
 407 end
 408
 409 -- Called every frame. Get the chain for displaying at input <num>,
 410 -- where 0 is live, 1 is preview, 2 is the first channel to display
 411 -- in the bottom bar, and so on up to num_channels()+1. t is the
 412 -- current time in seconds. width and height are the dimensions of
 413 -- the output, although you can ignore them if you don't need them
 414 -- (they're useful if you want to e.g. know what to resample by).
 415 --
 416 -- <signals> is basically an exposed InputState, which you can use to
 417 -- query for information about the signals at the point of the current
 418 -- frame. In particular, you can call get_width() and get_height()
 419 -- for any signal number, and use that to e.g. assist in chain selection.
 420 --
 421 -- You should return two objects; the chain itself, and then a
 422 -- function (taking no parameters) that is run just before rendering.
 423 -- The function needs to call connect_signal on any inputs, so that
 424 -- it gets updated video data for the given frame. (You are allowed
 425 -- to switch which input your input is getting from between frames,
 426 -- but not calling connect_signal results in undefined behavior.)
 427 -- If you want to change any parameters in the chain, this is also
 428 -- the right place.
 429 --
 430 -- NOTE: The chain returned must be finalized with the Y'CbCr flag
 431 -- if and only if num==0.
 432 function get_chain(num, t, width, height, signals)
 433         if num == 0 then  -- Live.
 434                 if live_signal_num == INPUT0_SIGNAL_NUM or live_signal_num == INPUT1_SIGNAL_NUM then  -- Plain input.
 435                         local input_type = get_input_type(signals, live_signal_num)
 436                         local input_scale = needs_scale(signals, live_signal_num, width, height)
 437                         local chain = simple_chains[input_type][input_scale][true]
 438                         prepare = function()
 439                                 chain.input:connect_signal(live_signal_num)
 440                                 set_scale_parameters_if_needed(chain, width, height)
 441                                 set_neutral_color_from_signal(chain.wb_effect, live_signal_num)
 442                         end
 443                         return chain.chain, prepare
 444                 elseif live_signal_num == STATIC_SIGNAL_NUM then  -- Static picture.
 445                         prepare = function()
 446                         end
 447                         return static_chain_hq, prepare
 448                 elseif live_signal_num == FADE_SIGNAL_NUM then  -- Fade.
 449                         local input0_type = get_input_type(signals, fade_src_signal)
 450                         local input0_scale = needs_scale(signals, fade_src_signal, width, height)
 451                         local input1_type = get_input_type(signals, fade_dst_signal)
 452                         local input1_scale = needs_scale(signals, fade_dst_signal, width, height)
 453                         local chain = fade_chains[input0_type][input0_scale][input1_type][input1_scale][true]
 454                         prepare = function()
 455                                 if input0_type == "live" then
 456                                         chain.input0.input:connect_signal(fade_src_signal)
 457                                         set_neutral_color_from_signal(chain.input0.wb_effect, fade_src_signal)
 458                                 end
 459                                 set_scale_parameters_if_needed(chain.input0, width, height)
 460                                 if input1_type == "live" then
 461                                         chain.input1.input:connect_signal(fade_dst_signal)
 462                                         set_neutral_color_from_signal(chain.input1.wb_effect, fade_dst_signal)
 463                                 end
 464                                 set_scale_parameters_if_needed(chain.input1, width, height)
 465                                 local tt = calc_fade_progress(t, transition_start, transition_end)
 466
 467                                 chain.mix_effect:set_float("strength_first", 1.0 - tt)
 468                                 chain.mix_effect:set_float("strength_second", tt)
 469                         end
 470                         return chain.chain, prepare
 471                 end
 472
 473                 -- SBS code (live_signal_num == SBS_SIGNAL_NUM).
 474                 local input0_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
 475                 local input1_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
 476                 if t > transition_end and zoom_dst == 1.0 then
 477                         -- Special case: Show only the single image on screen.
 478                         local input0_scale = needs_scale(signals, fade_src_signal, width, height)
 479                         local chain = simple_chains[input0_type][input0_scale][true]
 480                         prepare = function()
 481                                 chain.input:connect_signal(INPUT0_SIGNAL_NUM)
 482                                 set_scale_parameters_if_needed(chain, width, height)
 483                                 set_neutral_color(chain.wb_effect, input0_neutral_color)
 484                         end
 485                         return chain.chain, prepare
 486                 end
 487                 local chain = sbs_chains[input0_type][input1_type][true]
 488                 prepare = function()
 489                         if t < transition_start then
 490                                 prepare_sbs_chain(chain, zoom_src, width, height)
 491                         elseif t > transition_end then
 492                                 prepare_sbs_chain(chain, zoom_dst, width, height)
 493                         else
 494                                 local tt = (t - transition_start) / (transition_end - transition_start)
 495                                 -- Smooth it a bit.
 496                                 tt = math.sin(tt * 3.14159265358 * 0.5)
 497                                 prepare_sbs_chain(chain, zoom_src + (zoom_dst - zoom_src) * tt, width, height)
 498                         end
 499                 end
 500                 return chain.chain, prepare
 501         end
 502         if num == 1 then  -- Preview.
 503                 num = preview_signal_num + 2
 504         end
 505
 506         -- Individual preview inputs.
 507         if num == INPUT0_SIGNAL_NUM + 2 then
 508                 local input_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
 509                 local input_scale = needs_scale(signals, INPUT0_SIGNAL_NUM, width, height)
 510                 local chain = simple_chains[input_type][input_scale][false]
 511                 prepare = function()
 512                         chain.input:connect_signal(INPUT0_SIGNAL_NUM)
 513                         set_scale_parameters_if_needed(chain, width, height)
 514                         set_neutral_color(chain.wb_effect, input0_neutral_color)
 515                 end
 516                 return chain.chain, prepare
 517         end
 518         if num == INPUT1_SIGNAL_NUM + 2 then
 519                 local input_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
 520                 local input_scale = needs_scale(signals, INPUT1_SIGNAL_NUM, width, height)
 521                 local chain = simple_chains[input_type][input_scale][false]
 522                 prepare = function()
 523                         chain.input:connect_signal(INPUT1_SIGNAL_NUM)
 524                         set_scale_parameters_if_needed(chain, width, height)
 525                         set_neutral_color(chain.wb_effect, input1_neutral_color)
 526                 end
 527                 return chain.chain, prepare
 528         end
 529         if num == SBS_SIGNAL_NUM + 2 then
 530                 local input0_type = get_input_type(signals, INPUT0_SIGNAL_NUM)
 531                 local input1_type = get_input_type(signals, INPUT1_SIGNAL_NUM)
 532                 local chain = sbs_chains[input0_type][input1_type][false]
 533                 prepare = function()
 534                         prepare_sbs_chain(chain, 0.0, width, height)
 535                 end
 536                 return chain.chain, prepare
 537         end
 538         if num == STATIC_SIGNAL_NUM + 2 then
 539                 prepare = function()
 540                 end
 541                 return static_chain_lq, prepare
 542         end
 543 end
 544
 545 function place_rectangle(resample_effect, resize_effect, padding_effect, x0, y0, x1, y1, screen_width, screen_height, input_width, input_height)
 546         local srcx0 = 0.0
 547         local srcx1 = 1.0
 548         local srcy0 = 0.0
 549         local srcy1 = 1.0
 550
 551         -- Cull.
 552         if x0 > screen_width or x1 < 0.0 or y0 > screen_height or y1 < 0.0 then
 553                 resample_effect:set_int("width", 1)
 554                 resample_effect:set_int("height", 1)
 555                 resample_effect:set_float("zoom_x", screen_width)
 556                 resample_effect:set_float("zoom_y", screen_height)
 557                 padding_effect:set_int("left", screen_width + 100)
 558                 padding_effect:set_int("top", screen_height + 100)
 559                 return
 560         end
 561
 562         -- Clip.
 563         if x0 < 0 then
 564                 srcx0 = -x0 / (x1 - x0)
 565                 x0 = 0
 566         end
 567         if y0 < 0 then
 568                 srcy0 = -y0 / (y1 - y0)
 569                 y0 = 0
 570         end
 571         if x1 > screen_width then
 572                 srcx1 = (screen_width - x0) / (x1 - x0)
 573                 x1 = screen_width
 574         end
 575         if y1 > screen_height then
 576                 srcy1 = (screen_height - y0) / (y1 - y0)
 577                 y1 = screen_height
 578         end
 579
 580         if resample_effect ~= nil then
 581                 -- High-quality resampling.
 582                 local x_subpixel_offset = x0 - math.floor(x0)
 583                 local y_subpixel_offset = y0 - math.floor(y0)
 584
 585                 -- Resampling must be to an integral number of pixels. Round up,
 586                 -- and then add an extra pixel so we have some leeway for the border.
 587                 local width = math.ceil(x1 - x0) + 1
 588                 local height = math.ceil(y1 - y0) + 1
 589                 resample_effect:set_int("width", width)
 590                 resample_effect:set_int("height", height)
 591
 592                 -- Correct the discrepancy with zoom. (This will leave a small
 593                 -- excess edge of pixels and subpixels, which we'll correct for soon.)
 594                 local zoom_x = (x1 - x0) / (width * (srcx1 - srcx0))
 595                 local zoom_y = (y1 - y0) / (height * (srcy1 - srcy0))
 596                 resample_effect:set_float("zoom_x", zoom_x)
 597                 resample_effect:set_float("zoom_y", zoom_y)
 598                 resample_effect:set_float("zoom_center_x", 0.0)
 599                 resample_effect:set_float("zoom_center_y", 0.0)
 600
 601                 -- Padding must also be to a whole-pixel offset.
 602                 padding_effect:set_int("left", math.floor(x0))
 603                 padding_effect:set_int("top", math.floor(y0))
 604
 605                 -- Correct _that_ discrepancy by subpixel offset in the resampling.
 606                 resample_effect:set_float("left", srcx0 * input_width - x_subpixel_offset / zoom_x)
 607                 resample_effect:set_float("top", srcy0 * input_height - y_subpixel_offset / zoom_y)
 608
 609                 -- Finally, adjust the border so it is exactly where we want it.
 610                 padding_effect:set_float("border_offset_left", x_subpixel_offset)
 611                 padding_effect:set_float("border_offset_right", x1 - (math.floor(x0) + width))
 612                 padding_effect:set_float("border_offset_top", y_subpixel_offset)
 613                 padding_effect:set_float("border_offset_bottom", y1 - (math.floor(y0) + height))
 614         else
 615                 -- Lower-quality simple resizing.
 616                 local width = round(x1 - x0)
 617                 local height = round(y1 - y0)
 618                 resize_effect:set_int("width", width)
 619                 resize_effect:set_int("height", height)
 620
 621                 -- Padding must also be to a whole-pixel offset.
 622                 padding_effect:set_int("left", math.floor(x0))
 623                 padding_effect:set_int("top", math.floor(y0))
 624         end
 625 end
 626
 627 -- This is broken, of course (even for positive numbers), but Lua doesn't give us access to real rounding.
 628 function round(x)
 629         return math.floor(x + 0.5)
 630 end
 631
 632 function lerp(a, b, t)
 633         return a + (b - a) * t
 634 end
 635
 636 function prepare_sbs_chain(chain, t, screen_width, screen_height)
 637         chain.input0.input:connect_signal(0)
 638         chain.input1.input:connect_signal(1)
 639         set_neutral_color(chain.input0.wb_effect, input0_neutral_color)
 640         set_neutral_color(chain.input1.wb_effect, input1_neutral_color)
 641
 642         -- First input is positioned (16,48) from top-left.
 643         local width0 = round(848 * screen_width/1280.0)
 644         local height0 = round(width0 * 9.0 / 16.0)
 645
 646         local top0 = 48 * screen_height/720.0
 647         local left0 = 16 * screen_width/1280.0
 648         local bottom0 = top0 + height0
 649         local right0 = left0 + width0
 650
 651         -- Second input is positioned (16,48) from the bottom-right.
 652         local width1 = round(384 * screen_width/1280.0)
 653         local height1 = round(216 * screen_height/720.0)
 654
 655         local bottom1 = screen_height - 48 * screen_height/720.0
 656         local right1 = screen_width - 16 * screen_width/1280.0
 657         local top1 = bottom1 - height1
 658         local left1 = right1 - width1
 659
 660         -- Interpolate between the fullscreen and side-by-side views.
 661         local scale0, tx0, tx0
 662         if zoom_poi == INPUT0_SIGNAL_NUM then
 663                 local new_left0 = lerp(left0, 0, t)
 664                 local new_right0 = lerp(right0, screen_width, t)
 665                 local new_top0 = lerp(top0, 0, t)
 666                 local new_bottom0 = lerp(bottom0, screen_height, t)
 667
 668                 scale0 = (new_right0 - new_left0) / width0  -- Same vertically and horizonally.
 669                 tx0 = new_left0 - left0 * scale0
 670                 ty0 = new_top0 - top0 * scale0
 671         else
 672                 local new_left1 = lerp(left1, 0, t)
 673                 local new_right1 = lerp(right1, screen_width, t)
 674                 local new_top1 = lerp(top1, 0, t)
 675                 local new_bottom1 = lerp(bottom1, screen_height, t)
 676
 677                 scale0 = (new_right1 - new_left1) / width1  -- Same vertically and horizonally.
 678                 tx0 = new_left1 - left1 * scale0
 679                 ty0 = new_top1 - top1 * scale0
 680         end
 681
 682         top0 = top0 * scale0 + ty0
 683         bottom0 = bottom0 * scale0 + ty0
 684         left0 = left0 * scale0 + tx0
 685         right0 = right0 * scale0 + tx0
 686
 687         top1 = top1 * scale0 + ty0
 688         bottom1 = bottom1 * scale0 + ty0
 689         left1 = left1 * scale0 + tx0
 690         right1 = right1 * scale0 + tx0
 691         place_rectangle(chain.input0.resample_effect, chain.input0.resize_effect, chain.input0.padding_effect, left0, top0, right0, bottom0, screen_width, screen_height, 1280, 720)
 692         place_rectangle(chain.input1.resample_effect, chain.input1.resize_effect, chain.input1.padding_effect, left1, top1, right1, bottom1, screen_width, screen_height, 1280, 720)
 693 end
 694
 695 function set_neutral_color(effect, color)
 696         effect:set_vec3("neutral_color", color[1], color[2], color[3])
 697 end
 698
 699 function set_neutral_color_from_signal(effect, signal)
 700         if signal == INPUT0_SIGNAL_NUM then
 701                 set_neutral_color(effect, input0_neutral_color)
 702         else
 703                 set_neutral_color(effect, input1_neutral_color)
 704         end
 705 end
 706
 707 function calc_fade_progress(t, transition_start, transition_end)
 708         local tt = (t - transition_start) / (transition_end - transition_start)
 709         if tt < 0.0 then
 710                 tt = 0.0
 711         elseif tt > 1.0 then
 712                 tt = 1.0
 713         end
 714
 715         -- Make the fade look maybe a tad more natural, by pumping it
 716         -- through a sigmoid function.
 717         tt = 10.0 * tt - 5.0
 718         tt = 1.0 / (1.0 + math.exp(-tt))
 719
 720         return tt
 721 end