>> If you add filter_all to the image, it makes it transparent.
>> Alternatively, you can use a PNG with an alpha channel. You should
>> experiment to fing the best alpha value for your case. Do your tests for
>> a single "typical" frame.
>> Then, you add a normal point_light, possibly as a spot_light, behind the
>> "slide". Be sure to put a frame around your image to block any extra
>> light.
>
> Thanks - Sounds like exactly what I need. I'd prefer to avoid Alpha-PNG
> if possible - it would be better if I could do all the without
> pre-processing the frames I get (currently BMPs - Good job I recently
> got a new HDD)
>
>>
>> If there is anything between the slide and the screen, it's shadow will
>> be visible, and that thing will get illuminated.
>>
> Excellent
>
>> In that setup, there is no actual lense in your projector. Only an
>> absolutely punctual light_source and a slide/film. The image will be in
>> focus everywhere, not just on the screen.
>> If the "room" contains a light scattering media, then, that media will
>> show the projected beam.
> Fade distance is a good point, as is a lens - Is there any reason why I
> can't scale the image down, then use a lens with the appropriate steup
> to "project" the light? Or am I now moving into the realm of photons?
>
>> You may want to have the light's intensity change as a function of the
>> distance from the projector. For that, you need to use fade_power 2 and
>> fade_distance <something> for your light_source. The intensity of your
>> light should be increased to compensate the fading. In some cases, a
>> value of rgb 100 or even more can be required for the light_source.
>>
>> For the smoke, you should use some media. If the media itself is not
>> visible, but only it's effect is, then you should use an absorbing media.
>> If the "smoke" is to be visible, then you need to use scattering madia.
>>
>>
>> Alain
>
> Thanks :)
>

If you want to use a lens, then you absolutely need to use photons and 
make the lens a target and the slide set as pass_through. You'll 
probably also need to apply blured refraction to the slide so that you 
focus the slide instead of the lightsource. In that case, it's the slide 
than need to be made the photons' target.
Photons block needed for the lense or the slide (for blured refraction):
photons{target refraction on collect off}

Also, in that case, you'll need to flip your image just as in a real 
projector.


Alain

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