is there a better way to have 2d ui elements line up perfectly with a normal?

turtleguy955

ive been trying to make some 3d screens in a game im working on. getting the screens to work was the easy part (viewport with ui displaying on a sprite3d), but my problems start when i try to line the screens up to be in the spaces that i made on the 3d model. the screen placment areas are at a weird angles so i cant just eyeball it. before, i was using blender snapping to figure out the rotation values that i would need to give to the screen to have it lay flat, but this method is quite tedious so im looking for a better way of doing this.

xyz

turtleguy955 Are those screens Node3D derived objects?

turtleguy955

xyz yes

xyz

turtleguy955 Then just directly construct that node's global basis with surface normal as one of the basis vectors

turtleguy955

xyz im not exactly sure how i would do that, could you explain it a little?

xyz

turtleguy955 If the facing direction of your display is z you can construct display's global basis vectors like this:
z - surface normal
x - normalized cross product of global up and z
y - normalized cross product of x and z

This is basically a custom look_at.
Alternatively, you can simply use Basis::looking_at() with surface normal as the target argument.

turtleguy955

xyz im struggling to figure out how to get the surface normal, do you think you could tell me how to get that?

xyz

turtleguy955 Depending what the surface is. If you have a collider, do a raycast.

turtleguy955

xyz i got the surface normal numbers but past that im lost. i dont know a lot about vector math so thats probably why i am having such a hard time with this. is it at all possible to project the subviewport onto the face of the mesh itself? or even cut out that face in blender, import it seperatly, and project the viewport onto that?

xyz

turtleguy955 I thought you've got the texture part figured out. Simply make a quad mesh and assign viewport's texture to its material albedo. Later you can do it with a shader for some effects etc. Then call looking_at() on this quad's basis:

screen_quad.global_basis = screen_quad_global_basis.looking_at(normal)

Of course you also need to place it at the raycast hit position, probably slightly offset along the normal.

turtleguy955

xyz i didnt know i could set the texture in a material through albedo. i found a different way of displaying the viewports where i want them. by seperating the faces that the screens should be on in blender, then setting the albedo texture of each material to be the subviewport, i should be able to achieve what i want. this sadly has it own problem that being only 1px of the subviewport is showing up. if you know how to fix that it would be a big help, if not ill open a new post and see if anyone else does and, thank you for your help.

xyz

turtleguy955 Well that sounds fine. Just set proper UV map in Blender on the parts that need to display viewport texture. I assumed the screens are just rectangles. But you can have any complex geometry display the texture. It should be fine if all have the same material and tidy UVs.