Christopher James Huff wrote:
 > ...I
 > suspect tracing the environment map will take as long or longer than
 > just tracing reflected rays.

You're right for stills, but the speedup could be quite significant for 
animations (if the environment map can be re-used). Tracing several rays 
for _blurred_ reflections is quite expensive...

Warp wrote:
 > What you are doing there is projecting the scene onto the surface of
 > the object. That's not a reflection, not even close.

Sure, but you can project it onto a large, invisible (no_image, 
no_reflection) sphere. Here's a short scene that does the trick:
Set renderEnvMap to true and save the image as "envmap.png" (It uses a 
spherical camera).
Then set renderEnvMap to false and useEnvMap to true, be sure to correct 
the path to the previously rendered image, change the filename (to not 
overwrite the image-map) and render it to see the effect. Set useEnvMap 
to false to compare it with true reflections.

You could use focal blur (while rendering the environment map) or 
postprocessing to blur the image map. Alternatively you can use a 
photograpy as enveronment map (I'd use a cube with six pictures instead 
of the sphere then).

As Warp pointed out, this is just a fake, but if there are no other 
objects too close to the reflecting object no one will notice it ;-)

#declare renderEnvMap = true;
#declare useEnvMap = false;

#if (!renderEnvMap)
         camera {
                 location <0,15,-20>
                 look_at <0,3,0>
                 angle 50
         }
#else
         camera {
                 spherical
                 angle 360 180
                 location <0,3,0>
                 look_at <0,3,1>
         }
#end

plane {
         y, 0
         pigment { checker rgb 1 rgb 0}
         finish { ambient 0 diffuse 1 }
         #if (useEnvMap) no_reflection #end
}

cylinder {
         <-7,0,-2>,<-7,6,-2>,2
         pigment { color rgb <1,0,0> }
         finish { ambient 0 diffuse 1 specular 1 roughness 0.05 }
         #if (useEnvMap) no_reflection #end
}

cone {
         <7,0,-2>,2,<7,6,-2>,0
         pigment { color rgb <0,0,1> }
         finish { ambient 0 diffuse 1 specular 1 roughness 0.05 }
         #if (useEnvMap) no_reflection #end
}

light_source { <-100,100,-100> color rgb 0.6 }
light_source { <100,10,-100> color rgb 0.3 }
light_source { <0,100,100> color rgb 0.9 }

#if (!renderEnvMap)
         sphere {
                 <0,3,0>,3
                 finish { specular 5 roughness 0.002 reflection 1 }
         }
#end

#if (useEnvMap)
         sphere {
                 <0,0,0>,1
                 no_image
                 no_shadow
                 pigment { image_map { png "f:/envmap.png" map_type 1 } 
rotate <0,-90,0> }
                 finish { ambient 1 }
                 scale 100
                 translate <0,3,0>
         }
#end

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