shader_type canvas_item;

void fragment() {
	float dist_from_edge_x = .5 - abs(UV.x - .5);
	float dist_from_edge_y = .5 - abs(UV.y - .5);
	
	// dist_from_edge in pixels
	float dfe_xpx = dist_from_edge_x * 100.;
	float dfe_ypx = dist_from_edge_y * 40.;
	float dfe_px = min(dfe_xpx, dfe_ypx);
	
	COLOR.a *= dfe_px < 7.5 ? 1. : 0.;
}