Xna / OpenGL中的鱼眼投影矩阵 - 3D

Question

I'm looking for a projection matrix I can use in 3D that will give me the effect of a fisheye. I'm not looking for a pixelshader or anything like that, that will manipulate pixels - but the actual projection matrix used in projecting from 3D space onto 2D.

Thanks.

Answer 1

That's not really possible. In homogeneous coordinates, matrices transform lines to lines. So any solution based solely on matrices will necessarily fail to bend lines like you want to.

Answer 2

Carlos没错，但您可能想尝试使用投影矩阵构建器中的“视野（FOV）”参数。

Answer 3

Carlos is right. There is a way your could fake it, but you will have to re-render your scene multiple times.

Basically, you start by figuring out how to do two point perspective. Which I would do by rendering the scene twice with a projection matrix that has a vanishing point on alternating sides. Then you combine the two parts, I guess using a stencil map.

You could do something like four point perspective combining images with four vanishing points. You repeat that process as many times.

What your doing then is projecting onto a polygon that approximates a sphere.

I could explain more, but my guess is it sounds too complicated.

The simplest way to fake it is to render to a texture and distort the image, and render it as a fullscreen quad.