# Lecture 18: Lookat Matrix

`glm::lookat(vec3 eye, vec3 center, vec3 up)`

- with only
`eye`

and`center`

, infinite possibilities `up`

tells us which one

How do we construct the matrix?

## Camera Basis Vectors

**U:** “side”, “right”,

**V:**

**W:** “direction”, “forward”,

Actually, the **W** vector is the opposite of the “forward” vector of the camera.
This is because we are working in a *right-handed* coordinate system.

### Camera Matrix

### View Matrix

What we want is the view matrix, inverse of the camera matrix.

Because , , and are orthonormal basis vectors (and other matrix theorems etc.) the inverse of the above matrix is: