Normalizing UV coordinates to clip space (−1 to 1, aspect-ratio-corrected) makes shaders independent of canvas resolution

Raw fragCoord values range from 0 to canvas width/height in pixels, making shader behavior dependent on render resolution. The standard fix is to normalize: divide fragCoord by iResolution.xy to get 0–1 range, subtract 0.5 to center, then multiply by 2 to reach −1 to 1. A further correction multiplies the x component by the aspect ratio (iResolution.x / iResolution.y) to prevent horizontal stretching on non-square canvases. All in one line: vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y. This is the canonical opening move of virtually every shader art piece and must become automatic.

Examples

vec2 uv = (fragCoord * 2.0 - iResolution.xy) / iResolution.y;
// uv.x ranges from -aspect to +aspect
// uv.y ranges from -1 to +1
// origin (0,0) is center of canvas

Assessment

Without running code, predict what uv.xy contains for a pixel at the top-right corner of a 1600x900 canvas after applying the normalization above. Then implement the normalization and display uv.x in the red channel and uv.y in the green channel.