yuyaolong

I thought the 3DGS still using ray space like in EWA volume paper. Looks I am wrong, it's using [Projection matrix ](https://www.songho.ca/opengl/gl_projectionmatrix.html)here One more question: jsx should be -SX /...

"window to viewport" transform means NDC [-1~1] -> window coordinates [0 ~ WinWidth]? If so, that makes sense to me since the direction vector(vec2 d = gl_FragCoord.xy - frag_p;) is...