Projection With the(1x1x1) cube and Clipping

OpenGL
1

Using the site: http://www.songho.ca/opengl/gl_projectionmatrix.html

i see that the projection matrix is 1x1x1
why is that the way it is?

Could someone please explain this to me?

2

i see that the projection matrix is 1x1x1

Then you’re not looking at the same site you linked to. I see no projection matrix that is “1x1x1”.

Also, I don’t know how a matrix of any kind could only contain 3 numbers to begin with. Are you talking about an identity matrix? Because there isn’t one on that page.

Now, the post-projection space, normalized device coordinates (NDC) has the X, Y, and Z axes on the range [-1, 1]. But that’s not a matrix; that’s a space. Matrices transform from one space to another.

As to why NDC space is this way… it’s because OpenGL says so. OpenGL has to define some space, and it’s a convenient one for internal hardware computations.