+ if resample_effect ~= nil then
+ -- High-quality resampling.
+ local x_subpixel_offset = x0 - math.floor(x0)
+ local y_subpixel_offset = y0 - math.floor(y0)
+
+ -- Resampling must be to an integral number of pixels. Round up,
+ -- and then add an extra pixel so we have some leeway for the border.
+ local width = math.ceil(x1 - x0) + 1
+ local height = math.ceil(y1 - y0) + 1
+ resample_effect:set_int("width", width)
+ resample_effect:set_int("height", height)
+
+ -- Correct the discrepancy with zoom. (This will leave a small
+ -- excess edge of pixels and subpixels, which we'll correct for soon.)
+ local zoom_x = (x1 - x0) / (width * (srcx1 - srcx0))
+ local zoom_y = (y1 - y0) / (height * (srcy1 - srcy0))
+ resample_effect:set_float("zoom_x", zoom_x)
+ resample_effect:set_float("zoom_y", zoom_y)
+ resample_effect:set_float("zoom_center_x", 0.0)
+ resample_effect:set_float("zoom_center_y", 0.0)
+
+ -- Padding must also be to a whole-pixel offset.
+ padding_effect:set_int("left", math.floor(x0))
+ padding_effect:set_int("top", math.floor(y0))
+
+ -- Correct _that_ discrepancy by subpixel offset in the resampling.
+ resample_effect:set_float("left", srcx0 * input_width - x_subpixel_offset / zoom_x)
+ resample_effect:set_float("top", srcy0 * input_height - y_subpixel_offset / zoom_y)
+
+ -- Finally, adjust the border so it is exactly where we want it.
+ padding_effect:set_float("border_offset_left", x_subpixel_offset)
+ padding_effect:set_float("border_offset_right", x1 - (math.floor(x0) + width))
+ padding_effect:set_float("border_offset_top", y_subpixel_offset)
+ padding_effect:set_float("border_offset_bottom", y1 - (math.floor(y0) + height))
+ else
+ -- Lower-quality simple resizing.
+ local width = round(x1 - x0)
+ local height = round(y1 - y0)
+ resize_effect:set_int("width", width)
+ resize_effect:set_int("height", height)
+
+ -- Padding must also be to a whole-pixel offset.
+ padding_effect:set_int("left", math.floor(x0))
+ padding_effect:set_int("top", math.floor(y0))
+ end
+end
+
+-- This is broken, of course (even for positive numbers), but Lua doesn't give us access to real rounding.
+function round(x)
+ return math.floor(x + 0.5)
+end
+
+function lerp(a, b, t)
+ return a + (b - a) * t
+end
+
+function lerp_pos(a, b, t)
+ return {
+ x0 = lerp(a.x0, b.x0, t),
+ y0 = lerp(a.y0, b.y0, t),
+ x1 = lerp(a.x1, b.x1, t),
+ y1 = lerp(a.y1, b.y1, t)
+ }
+end
+
+function pos_from_top_left(x, y, width, height, screen_width, screen_height)
+ local xs = screen_width / 1280.0
+ local ys = screen_height / 720.0
+ return {
+ x0 = round(xs * x),
+ y0 = round(ys * y),
+ x1 = round(xs * (x + width)),
+ y1 = round(ys * (y + height))
+ }
+end
+
+function prepare_sbs_chain(state, chain, t, transition_type, src_signal, dst_signal, screen_width, screen_height, input_resolution)
+ chain.input0.input:connect_signal(0)
+ chain.input1.input:connect_signal(1)
+ set_neutral_color(chain.input0.wb_effect, state.neutral_colors[1])
+ set_neutral_color(chain.input1.wb_effect, state.neutral_colors[2])
+
+ -- First input is positioned (16,48) from top-left.
+ -- Second input is positioned (16,48) from the bottom-right.
+ local pos0 = pos_from_top_left(16, 48, 848, 477, screen_width, screen_height)
+ local pos1 = pos_from_top_left(1280 - 384 - 16, 720 - 216 - 48, 384, 216, screen_width, screen_height)
+
+ local pos_fs = { x0 = 0, y0 = 0, x1 = screen_width, y1 = screen_height }
+ local affine_param
+ if transition_type == NO_TRANSITION then
+ -- Static SBS view.
+ affine_param = { sx = 1.0, sy = 1.0, tx = 0.0, ty = 0.0 } -- Identity.
+ else
+ -- Zooming to/from SBS view into or out of a single view.
+ assert(transition_type == ZOOM_TRANSITION)
+ local signal, real_t
+ if src_signal == SBS_SIGNAL_NUM then
+ signal = dst_signal
+ real_t = t
+ else
+ assert(dst_signal == SBS_SIGNAL_NUM)
+ signal = src_signal
+ real_t = 1.0 - t
+ end