Camera.projectionMatrix

Description

Set a custom projection matrix.

If you change this matrix, the camera no longer updates its rendering based on its fieldOfView. Moreover, this leaves the camera's nearClipPlane and farClipPlane unchanged, so you need to update those manually to avoid inconsistencies. This lasts until you call ResetProjectionMatrix.

Use a custom projection only if you really need a non-standard projection. This property is used by Unity's water rendering to setup an oblique projection matrix. Using custom projections requires good knowledge of transformation and projection matrices.

Note that projection matrix passed to shaders can be modified depending on platform and other state. If you need to calculate projection matrix for shader use from camera's projection, use GL.GetGPUProjectionMatrix.

Additional resources: Camera.nonJitteredProjectionMatrix

// Make camera wobble in a funky way!
using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    public Matrix4x4 originalProjection;
    Camera cam;

    void Start()
    {
        cam = GetComponent<Camera>();
        originalProjection = cam.projectionMatrix;
    }

    void Update()
    {
        Matrix4x4 p = originalProjection;
        p.m01 += Mathf.Sin(Time.time * 1.2F) * 0.1F;
        p.m10 += Mathf.Sin(Time.time * 1.5F) * 0.1F;
        cam.projectionMatrix = p;
    }
}

// Set an off-center projection, where perspective's vanishing
// point is not necessarily in the center of the screen.
//
// left/right/top/bottom define near plane size, i.e.
// how offset are corners of camera's near plane.
// Tweak the values and you can see camera's frustum change.

using UnityEngine;
using System.Collections;

[ExecuteInEditMode]
public class ExampleClass : MonoBehaviour
{
    public float left = -0.2F;
    public float right = 0.2F;
    public float top = 0.2F;
    public float bottom = -0.2F;
    void LateUpdate()
    {
        Camera cam = Camera.main;
        Matrix4x4 m = PerspectiveOffCenter(left, right, bottom, top, cam.nearClipPlane, cam.farClipPlane);
        cam.projectionMatrix = m;
    }

    static Matrix4x4 PerspectiveOffCenter(float left, float right, float bottom, float top, float near, float far)
    {
        float x = 2.0F * near / (right - left);
        float y = 2.0F * near / (top - bottom);
        float a = (right + left) / (right - left);
        float b = (top + bottom) / (top - bottom);
        float c = -(far + near) / (far - near);
        float d = -(2.0F * far * near) / (far - near);
        float e = -1.0F;
        Matrix4x4 m = new Matrix4x4();
        m[0, 0] = x;
        m[0, 1] = 0;
        m[0, 2] = a;
        m[0, 3] = 0;
        m[1, 0] = 0;
        m[1, 1] = y;
        m[1, 2] = b;
        m[1, 3] = 0;
        m[2, 0] = 0;
        m[2, 1] = 0;
        m[2, 2] = c;
        m[2, 3] = d;
        m[3, 0] = 0;
        m[3, 1] = 0;
        m[3, 2] = e;
        m[3, 3] = 0;
        return m;
    }
}