Scaling a shape

Same idea for size. To make a shape bigger, make every pixel look at a position that is closer to the middle: divide by the scale.

Check: with p / 2.0 the pixel at x = 0.4 looks at 0.2, so a shape that ends at 0.2 now reaches all the way out to 0.4: twice as big. You can scale each direction separately: p / float2(2.0, 1.0) stretches only horizontally.

This lesson also introduces a ready-made helper, sdBox(p, halfSize). It gives the distance from p to a box: negative inside, 0 on the edge, positive outside. You don't have to understand its insides yet. Use the Toolbox button to add it.

To turn a distance into a picture: m = 1.0 - smoothstep(0.0, 0.01, d); is 1 inside, 0 outside, with a thin soft edge.

float2 p = (uv - 0.5) * float2(aspect, 1.0);
p = p / float2(2.0, 1.0);       // twice as wide, same height