Address review feedback

src/shaders/sprite.frag

@@ -234,7 +234,8 @@ void main()
 
 	// Avoid division by zero
 	float baDot = dot(ba, ba);
-	baDot = (abs(baDot) < epsilon) ? epsilon : baDot;
+	// the dot product of a vector and itself is always positive
+	baDot = max(baDot, epsilon);
 
 	// Magnitude of vector projection of this fragment onto the line (both relative to the line's start point).
 	// This results in a "linear gradient" which goes from 0.0 at the start point to 1.0 at the end point.

src/shaders/sprite.vert

@@ -42,7 +42,10 @@ void main() {
 	// Rotate quad to line angle
 	vec2 pointDiff = u_penPoints.zw - u_penPoints.xy;
 	// Ensure line has a nonzero length so it's rendered properly
+	// As long as either component is nonzero, the line length will be nonzero
 	pointDiff.x = abs(pointDiff.x) < epsilon ? epsilon : pointDiff.x;
+	// The `normalized` vector holds rotational values equivalent to sine/cosine
+	// We're applying the standard rotation matrix formula to the position to rotate the quad to the line angle
 	vec2 normalized = pointDiff / max(lineLength, epsilon);
 	position = mat2(normalized.x, normalized.y, -normalized.y, normalized.x) * position;
 	// Translate quad