- local new_left1 = lerp(left1, 0, t)
- local new_right1 = lerp(right1, screen_width, t)
- local new_top1 = lerp(top1, 0, t)
- local new_bottom1 = lerp(bottom1, screen_height, t)
-
- scale0 = (new_right1 - new_left1) / width1 -- Same vertically and horizonally.
- tx0 = new_left1 - left1 * scale0
- ty0 = new_top1 - top1 * scale0
- end
-
- top0 = top0 * scale0 + ty0
- bottom0 = bottom0 * scale0 + ty0
- left0 = left0 * scale0 + tx0
- right0 = right0 * scale0 + tx0
-
- top1 = top1 * scale0 + ty0
- bottom1 = bottom1 * scale0 + ty0
- left1 = left1 * scale0 + tx0
- right1 = right1 * scale0 + tx0
- 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)
- 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)
+ affine_param = find_affine_param(pos1, lerp_pos(pos1, pos_fs, t))
+ end
+
+ -- NOTE: input_resolution is not 1-indexed, unlike usual Lua arrays.
+ place_rectangle_with_affine(chain.input0.resample_effect, chain.input0.resize_effect, chain.input0.padding_effect, pos0, affine_param, screen_width, screen_height, input_resolution[0].width, input_resolution[0].height)
+ place_rectangle_with_affine(chain.input1.resample_effect, chain.input1.resize_effect, chain.input1.padding_effect, pos1, affine_param, screen_width, screen_height, input_resolution[1].width, input_resolution[1].height)
+end
+
+-- Find the transformation that changes the first rectangle to the second one.
+function find_affine_param(a, b)
+ local sx = (b.x1 - b.x0) / (a.x1 - a.x0)
+ local sy = (b.y1 - b.y0) / (a.y1 - a.y0)
+ return {
+ sx = sx,
+ sy = sy,
+ tx = b.x0 - a.x0 * sx,
+ ty = b.y0 - a.y0 * sy
+ }
+end
+
+function place_rectangle_with_affine(resample_effect, resize_effect, padding_effect, pos, aff, screen_width, screen_height, input_width, input_height)
+ local x0 = pos.x0 * aff.sx + aff.tx
+ local x1 = pos.x1 * aff.sx + aff.tx
+ local y0 = pos.y0 * aff.sy + aff.ty
+ local y1 = pos.y1 * aff.sy + aff.ty
+
+ place_rectangle(resample_effect, resize_effect, padding_effect, x0, y0, x1, y1, screen_width, screen_height, input_width, input_height)