Fix line width calculation

It was only correct at the screen center

src/bin/wireframe/ray.wgsl

@@ -48,7 +48,8 @@ fn vs_main(seg: SegmentInput, off: OffsetInput) -> VertexOutput {
 	default: {}
 	}
 	let pt_cs = camera.mvp * vec4(pt, 1.);
-	let dir_cs = camera.mvp * vec4(dir, 0.);
+	let dir_cs0 = camera.mvp * vec4(dir, 0.);
+	let dir_cs = dir_cs0.xyz * pt_cs.w - pt_cs.xyz * dir_cs0.w;
 	let normal_cs = camera.scale * normalize(vec2(-dir_cs.y, dir_cs.x));
 	out.clip_position = pt_cs + vec4(sgn * width * normal_cs, 0., 0.);
 	return out;

src/bin/wireframe/viewport.rs

@@ -29,7 +29,7 @@ impl<'a> Viewport<'a> {
 			format,
 			width: size.x,
 			height: size.y,
-			present_mode: caps.present_modes[0],
+			present_mode: wgpu::PresentMode::Fifo,
 			alpha_mode: caps.alpha_modes[0],
 			view_formats: vec![],
 			desired_maximum_frame_latency: 2,