Mail Archives: djgpp/1998/04/29/02:17:05
In article <D1FB30BBA491D1118E6D006097BCAE392DBB06 AT Probe-nt-2a DOT Probe DOT co DOT uk>,
ShawnH AT Probe DOT co DOT uk was heard to ramble thus:
[snip]
>Lensflare is an additive effect: a black flare value should leave
>the original color unchanged, while lighter flare colors will
>increase the brightness of the screen color. To do this in Allegro,
>you will need to make a custom mapping table (using the
>create_color_table() function). In your blender function callback,
>just add the two rgb values, clamping to white if the result
>overflows.
Additive color.
<smacks forehead>
Thanks =)
(An additive color table would be great for some other funky things...
especially really cool explosions. I'm pretty sure I could get an effect
similar to the Allegro demo's explosions, but generated on the fly. Then
there's lightmaps and other funky lighting effects like fake speculars. Shawn:
you should put an additive-color-map-generating function into Allegro, or an
additive draw mode - just to make coding easier for poor lazy plebs like me =)
>If you can't afford the memory for an extra mapping table, you can
>get fairly decent effects using normal interpolating translucency,
>if you draw the flares using very pale colors and not too solid.
>I have to do them this way on the N64 at work (it doesn't support
>additive color), and it doesn't look too far off as long as you
>use sensible source images.
That might work fairly well, too.
>In terms of making things look nice, the important thing is not to
>overdo it: make the flares quite subtle. Position them at irregular
>intervals along your light vector: tweaking these numbers can make
>a big difference to how smoothly they move as the light source moves
>around the screen. If you can do variable translucency levels (by
>using a truecolor mode, multiple color mapping tables, or different
>versions of the flare graphics), try fading out the alpha as the
>light source moves towards the edges of the screen.
Instead of putting lens flares along a light vector (which would look supremely
cool - hehe) I was actually thinking of blitting a single flare centered over
the light source. Actually, I hadn't heard of the term 'light vector' until
you mentioned it - I'm assuming (from the lens flare filters in my graphics
package) that it's just a vector from the light source that passes through the
center of the screen?
<off_topic severity=mild>
Any other cool graphics tricks floating around this newsgroup's collective
brain?
</off_topic>
--
Demandred, Lord of the 32-bit Registers
mail to: demandrd 'at' compusmart 'dot' ab 'dot' ca
http://www.nnetis.ca/~matt/dogfight.html
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