Ray3d::from_screenspace() implementation from Camera.viewport_to_world()

[rosingrind]

Summary

bevyengine/bevy#8306 introduces consistent coordinates for every entity without .y flipping. The changes are not rolled out yet, but current main of bevy_mod_raycast is not working well with bevy's main. In attempt to fix this, I found a simple but questionable solution:

bevy_mod_raycast/src/primitives.rs

Lines 240 to 262 in bd84951

	pub fn from_screenspace(
	cursor_pos_screen: Vec2,
	camera: &Camera,
	camera_transform: &GlobalTransform,
	) -> Option<Self> {
	let view = camera_transform.compute_matrix();
	let (viewport_min, viewport_max) = camera.logical_viewport_rect()?;
	let screen_size = camera.logical_target_size()?;
	let viewport_size = viewport_max - viewport_min;
	let adj_cursor_pos =
	cursor_pos_screen - Vec2::new(viewport_min.x, screen_size.y - viewport_max.y);
	let projection = camera.projection_matrix();
	let far_ndc = projection.project_point3(Vec3::NEG_Z).z;
	let near_ndc = projection.project_point3(Vec3::Z).z;
	let cursor_ndc = (adj_cursor_pos / viewport_size) * 2.0 - Vec2::ONE;
	let ndc_to_world: Mat4 = view * projection.inverse();
	let near = ndc_to_world.project_point3(cursor_ndc.extend(near_ndc));
	let far = ndc_to_world.project_point3(cursor_ndc.extend(far_ndc));
	let ray_direction = far - near;
	Some(Ray3d::new(near, ray_direction))
	}

is equal to

https://github.com/bevyengine/bevy/blob/585baf0a66b855cef1f0568a4af44b666cfee076/crates/bevy_render/src/camera/camera.rs#L250-L270

Solution

It seems that there's no reason not to utilize Camera::viewport_to_world() as it's available since bevyengine/bevy@37860a0 from v0.9.0. I propose to utilize Camera.viewport_to_world() under the hood of Ray3d::from_screenspace() as their purposes seems identical. Changes doesn't seem to break any examples functionality on my end

[rosingrind]

Closing this in favor of #78 and #83