1 files changed, 18 insertions(+), 0 deletions(-)

M public/script.js

@@ 273,7 273,25 @@ function render() {
     ctx.clearRect(0, 0, can.width, can.height);
     const det = getDet();
     if (Math.abs(det) > LOW_DET_THRESH) {
+        // full rank, render a grid
         renderGrid(renderOpts, ctx);
+    } else {
+        const distFromOrigin = [state.ihat, state.jhat].map(vec => Math.abs(vec.reduce((a, b) => a + b))).reduce((a, b) => a + b);
+        if (distFromOrigin > 0.1) {
+            // rank 1, render a line
+            // if det is 0 then ihat's tip, jhat's tip, and the origin will all be on a line
+            // but when it's almost 0, do some trickery to get the line to look right
+
+            // TODO: properly extend to screen edges
+            const points = [
+                transformPoint(state.ihat).map(x => x * 100),
+                [0, 0],
+                transformPoint(state.jhat).map(x => x * 100),
+            ];
+
+            renderLine(renderOpts, "black", false, points[0], points[2], ctx, x => x);
+        }
+        // draw nothing repersenting the transformation for rank 0
     }
 
     // unit vectors