Ultima VII Perspective Breakdown (3D)

Hello! This is my first post.
Okay, so, im trying to get a certain perspective to work into Unity.
The idea is to get the perspective of Ultima VII working with a 3D object.
So far, i've reached half the way through by messing the camera rotation and aspect ratio.
But heres the thing, the only step missing to make the perspective look perfect, is for the scene to rotate on its flat axis (x and y) by 45º
Heres what im trying to do, illustrated:

The idea is to get to the last image, but i can't :|
What i did to get to the second image is to adjust the aspect ratio and the camera angles, but rotating the scene in the Z axis messes around with the second image, so its not entirely possible.
I've thought about stacking 2 cameras to get the result, but this doesn't seem to work, so thats why im asking for help...
So, any help would be appreciated, thanks!

 

So, i managed to do this using render texture:

But this is a very weird solution, mostly because its gonna be freaking hard to get the resolution just right.
If anyone got any idea of how to make this simpler, please, feel free to post here

 

...I'm sorry but I actually laughed out loud when seeing this. It seems so ridiculously overcomplicated. As a thanks, here's a way that sort of makes it work the sort of intended way:

Set your camera rotation to (65,-30,-30) or similar. And then it look like this:



It's not exactly the thing as in proper 2.5D, but it's quite close. You'll probably need a custom projection matrix or dedicated art to do the final bit.

Edit: I'm stupid. Took my 7 edits. Final version!

 

Thanks for the effort! But as i said before, the idea is to simulate the perspective from Ultima VII, the top of the cube should create a perfect square, just like in my final picture, or like, this one:

I managed to get to half that result by searching a little bit into google and finding this discussion:
http://opengameart.org/forumtopic/reverse-engineering-ultima-vii-isometrics-wip
If you look into the link, you'll find a person that managed to do it using Blender, and i've managed to follow his instructions up until the part he just says "now flip it all 45º" which comes back to this topic.
So... yeah. But thanks for the effort anyways!

 

Try using a vertex shader to skew the scene rather than rotating the camera.

 

Oh, that might actually work, im guessing setting the camera to a top view, and then skewing all the vertices along the Y axis by a 45 degree angle, that makes sense.
Im a complete noob when it comes to shaders though, im looking into a few tutorials and pages about it and honestly i feel completely lost. I know how to edit the mesh through a c# script though, is there a difference between those two? I know that the c# script will have to loop through all the vertices and change their positions individualy, are the shaders more efficient in this case? And can i apply a single shader to all my meshes on the scene?

 

http://www.alanzucconi.com/2015/06/10/a-gentle-introduction-to-shaders-in-unity3d/

When you get further along the bit of code you'll need is something like this.

float4 worldPos = mul(_Object2World, v.vertex);
worldPos.xy += worldPos.z;
o.vertex = mul(UNITY_MATRIX_MVP, mul(_World2Object, worldPos));

That might make more sense to you once you've gotten through part4 of the above tutorial.

edit: Btw, what you're trying to do is skew or shear the scene, not rotate it.

 

Well, turns out everyone is being silly here.

Check: http://docs.unity3d.com/Manual/ObliqueFrustum.html

So just adding a script like this:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class TestScript : MonoBehaviour {
5.     public float AngleX = -0.03f;
6.     public float AngleY = 0.09f;
7.  
8.     void Update () {
9.         Matrix4x4 matrix = Camera.main.projectionMatrix;
10.         matrix [0, 2] = AngleX;
11.         matrix [1, 2] = AngleY;
12.         Camera.main.projectionMatrix = matrix;
13.     }
14. }
15.  

somewhere already makes it work (Further away from ortho camera = more translated to bottomright).

With the added benefits that the entire lighting system works with it, and frustrum culling as well.

The ratio between the 2 angles depends on the aspect ratio used btw.

 

Except that completely breaks real time shadows, otherwise it's a good solution.

 

Yeah, i managed to do it both ways, the simpler way was to just add the camera script, but they both don't seem to work well with shadows. So i guess the idea is to use the script for the distortion and the shader to create shadows (since shadows are pretty much skewed black textures)
Heres the final result

And uh, heres how it works with the shader btw
But theres also the possibility that im F***ing something up on the shader code too... not really sure

 

For the shader version you'll want to add addshadow to your #pragma surf line, assuming you're using a surface shader.

 

Actually, see this:

http://issuetracker.unity3d.com/iss...asts-it-when-using-a-custom-projection-matrix

Realtime shadows work with the projection matrix variant in 5.3.0? I'd say that makes it a better way of doing this then the vertex moving.

 

Thanks to bgolus i got the shader working perfectly, even with realtime shadows.
If anyones interested, i can post the code here
So i guess this is it! Problem solved.

 

Hey! I would love to see how you managed to get it done. I know this is a very old thread, but I can't find a way to send you a private message about it

 

This is quite an old thread but I'd be very interested in your code!

 

hey got late to the party...I would really appreciate if u can share how u got it

 

I second this...