fix glsl errors

fix a bunch of glsl compile errors

Plugin-TypeSplatCloud/Shaders/SplatCloud_ShaderGen/dots_psize_vs.glsl

@@ -33,7 +33,7 @@ void main()
   gl_PointSize = max(viewportScaleFov_y * ecPointsize  / gl_Position.w, 1.0);
 
   // use generated SG_OUTPUT variables to do backface culling
-  if (backfaceCulling &&  dot(SG_OUTPUT_POSVS, SG_OUTPUT_NORMALVS)  > 0.0)
+  if (backfaceCulling &&  dot(SG_OUTPUT_POSVS.xyz, SG_OUTPUT_NORMALVS)  > 0.0)
   {
     // discard vertex
     gl_Position.w = 0.0;