openRNDR slit scan example. each pixel can come from a different frame in the image sequence.

PixelOffset.kt

import org.openrndr.WindowMultisample
import org.openrndr.application
import org.openrndr.draw.ImageFileFormat
import org.openrndr.draw.arrayTexture
import org.openrndr.draw.loadImage
import org.openrndr.draw.shadeStyle
import org.openrndr.extra.compositor.compose
import org.openrndr.extra.compositor.draw
import org.openrndr.extra.compositor.layer
import org.openrndr.extra.compositor.post
import org.openrndr.extra.fx.blur.FrameBlur
import org.openrndr.ffmpeg.MP4Profile
import org.openrndr.ffmpeg.ScreenRecorder

fun main() = application {

    configure {
        width = 1080
        height = 1080
    }

    program {

        val totalFrames = 150
        val inputDir = "frames/"
        val outputDir = "frames-out/"
        val arrayTexture = arrayTexture(width, height, totalFrames)


        fun loadFrames() {
            println("loading frames...")
            for (frame in 1 .. totalFrames) {
                val file = "${inputDir}frame_%04d.png".format(frame)
                val colorBuffer = loadImage(file, formatHint = ImageFileFormat.PNG)
                colorBuffer.copyTo(arrayTexture, frame - 1)
                colorBuffer.destroy()
            }
            println("done loading frames")
        }

        loadFrames()

        val composite = compose {
            layer {
                draw {
                    val frame = (frameCount - 1) % totalFrames
                    val t = frame / totalFrames.toDouble()

                    drawer.shadeStyle = shadeStyle {
                        fragmentPreamble = """
                            float rand(vec2 co){
                                return fract(sin(dot(co, vec2(12.9898, 78.233))) * 43758.5453);
                            }
                        """.trimIndent()

                        fragmentTransform = """
                            vec2 pos = c_boundsPosition.xy;
                            float dist = distance(pos, vec2(0.5, 0.5));
                            dist += 0.010 * rand(pos) - 0.005;
                            float timeOffset = fract(p_time - dist + 2.0);
                            float framePct = p_totalFrames * timeOffset;
                            int frame1 = (p_frame + int(framePct)) % p_totalFrames;
                            int frame2 = (frame1 + 1) % p_totalFrames;
                            x_fill = mix(
                                texture(p_arrayTexture, vec3(pos, frame1)),
                                texture(p_arrayTexture, vec3(pos, frame2)),
                                fract(framePct)
                            );
                        """.trimIndent()

                        parameter("arrayTexture", arrayTexture)
                        parameter("frame", frame)
                        parameter("totalFrames", totalFrames)
                        parameter("time", t)
                    }
                    drawer.rectangle(drawer.bounds)
                }
                post(FrameBlur()) {
                    blend = 0.5
                }
            }
        }

        extend(ScreenRecorder()) {
            outputFile = outputDir + "cross-swap.mp4"
            profile = MP4Profile().apply { mode(MP4Profile.WriterMode.Lossless) }
            frameRate = 30
            frameSkip = 10
            maximumFrames = totalFrames.toLong()
            quitAfterMaximum = true
        }

        extend {
            composite.draw(drawer)
        }
    }
}