Setting camera projection matrix breaks shadows and skybox

I am setting a custom projection matrix. The problem is that dynamic shadows and skybox functionality breaks down when doing this. When I looked through the forum and answer section I saw that others have had the same problem:

http://answers.unity3d.com/question...the-camera-projection-matrix.html?sort=oldest
http://forum.unity3d.com/threads/41404-Camera.projectionMatrix-breaks-shadows-and-imagefx
http://answers.unity3d.com/questions/17305/off-centre-projection-matrix-breaks-cascaded-shado.html
http://answers.unity3d.com/questions/54090/changing-cameraprojectionmatrix-doesnt-affect-skyb.html
http://forum.unity3d.com/threads/32538-Custom-frustum-Render-to-texture

Does anyone have a solution to this?

 

Well at least I have tracked down the shadow problem. If I use Forward rendering instead of deferred rendering, shadows work properly.

If anyone else want to experience the problem, try using the following script on your camera and enable deferred rendering:

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. [ExecuteInEditMode]
5.  
6. public class AsymetricProjection : MonoBehaviour {
7.     public bool enable = true;
8.     Matrix4x4 default_matrix;
9.  
10.     void start() {
11.         default_matrix = camera.projectionMatrix;
12.     }
13.  
14.     void LateUpdate() {
15.         Matrix4x4 m = new Matrix4x4();
16.         m[0, 0] = 2.21687f;
17.         m[0, 1] = -0.02983f;
18.         m[0, 2] = -0.00969f;
19.         m[0, 3] = 0.00000f;
20.         m[1, 0] = 0.05348f;
21.         m[1, 1] = 4.01233f;
22.         m[1, 2] = -0.14524f;
23.         m[1, 3] = 0.00000f;
24.         m[2, 0] = -0.00154f;
25.         m[2, 1] = -0.02675f;
26.         m[2, 2] = -0.99984f;
27.         m[2, 3] = -2.00020f;
28.         m[3, 0] = -0.00154f;
29.         m[3, 1] = -0.02675f;
30.         m[3, 2] = -0.99964f;
31.         m[3, 3] = 0.00000f;
32.         if (enable) {
33.             camera.projectionMatrix = m;
34.         }
35.         else {
36.             camera.projectionMatrix = default_matrix;
37.             camera.ResetProjectionMatrix();
38.         }
39.     }
40. }

When script is enabled shadows are jumping around depending on camera position.

 

I have logged the following bug reports for these:

For the broken shadows when using deferred rendering:
https://fogbugz.unity3d.com/default.asp?491430_6vbu7vhngcmsh78r

For the skybox that do not change the field of view:
https://fogbugz.unity3d.com/default.asp?491708_cpmprvvus5pl85qd

 

Well, I think I have solved this. You will need to recalculate the aspect ratio and the field of view for the asymmetric projection matrix.

Lets use the example found here:
http://docs.unity3d.com/Documentation/ScriptReference/Camera-projectionMatrix.html

And extend it with code that calculates and sets the aspect and field of view:

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. [ExecuteInEditMode]
5. public class OffProjection : MonoBehaviour {
6.     public float left = -0.2F;
7.     public float right = 0.2F;
8.     public float top = 0.2F;
9.     public float bottom = -0.2F;
10.    
11.     void LateUpdate() {
12.         Camera cam = camera;
13.         float width = (right - left);
14.         float height = (top - bottom);
15.         cam.aspect = width/height;
16.         float fov = (Mathf.Atan(top/cam.nearClipPlane) - Mathf.Atan(bottom/cam.nearClipPlane)) * 57.2957795f;
17.         cam.fieldOfView = fov;
18.  
19.         Matrix4x4 m = PerspectiveOffCenter(left, right, bottom, top, cam.nearClipPlane, cam.farClipPlane);
20.         cam.projectionMatrix = m;
21.     }
22.    
23.     static Matrix4x4 PerspectiveOffCenter(float left, float right, float bottom, float top, float near, float far) {
24.         float x = 2.0F * near / (right - left);
25.         float y = 2.0F * near / (top - bottom);
26.         float a = (right + left) / (right - left);
27.         float b = (top + bottom) / (top - bottom);
28.         float c = -(far + near) / (far - near);
29.         float d = -(2.0F * far * near) / (far - near);
30.         float e = -1.0F;
31.         Matrix4x4 m = new Matrix4x4();
32.         m[0, 0] = x;
33.         m[0, 1] = 0;
34.         m[0, 2] = a;
35.         m[0, 3] = 0;
36.         m[1, 0] = 0;
37.         m[1, 1] = y;
38.         m[1, 2] = b;
39.         m[1, 3] = 0;
40.         m[2, 0] = 0;
41.         m[2, 1] = 0;
42.         m[2, 2] = c;
43.         m[2, 3] = d;
44.         m[3, 0] = 0;
45.         m[3, 1] = 0;
46.         m[3, 2] = e;
47.         m[3, 3] = 0;
48.         return m;
49.     }
50. }

 

@BjornVTI, is this implementation for forward or deferred rending? I've tried both and my shadows still don't show up for deferred rendering.

 

Hi, just wanted to ping this thread as I also need a solution for custom projection matrix rendering.
The solution above is not working, was maybe done in an earlier version on Unity?

If I understand correctly, there is a pass in which the projection matrix is used in a simpler form (probably to speed up rendering). If someone could give me a hint on how to modify the default shaders, I would like to take a deeper look.

 

@DaveTheVR Check this forum, for an implementation that works:
http://forum.unity3d.com/threads/us...reate-holographic-effect.291123/#post-2114192

Also, Unity has a bug in its lighting/shadowing system right now, which we've marked in the IssueTracker. It'd help if you voted for it here.