Raster Effect
Graphics effect that manipulates screen coordinates on a per-scanline basis while the display is actively being drawn, creating the illusion of warping and distortion.
A monitor scans from top to bottom, line by line. By synchronizing CPU code to interrupt exactly when each line draws, you can shift coordinates for that specific scanline before it appears. Amiga demos became famous for bending landscapes, warping water, and creating impossible geometries—all in real time, all by manipulating a handful of registers and millisecond-precise timing. Raster effects represent the marriage of hardware expertise and creative problem-solving that define the demoscene.