size(400, 400, P3D);
noStroke();
background(0);
lightFalloff(1.0, 0.001, 0.0);
pointLight(150, 250, 150, 200, 200, 200);
beginShape();
vertex(0, 0, 0);
vertex(400, 0, -400);
vertex(400, 400, -400);
vertex(0, 400, 0);
endShape(CLOSE);