StuartK
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The small shadows that are part of the creature art and some objects in GeneralTiles.bmp are not calculated correctly when placed ontop of each other in a room. An obvious example being tar babies on tar, as the floor colour is noticeable around the edge of the tar baby, but other objects equally apply (tar on walls etc) when the mid-blue shadow 'colour' is used in their art.

Shadows should be calculated based on the colour of the object underneath, rather than just the floor colour for that square.

[Edited by StuartK on 07-13-2003 at 09:40 AM]

trick
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This could also be fixed by making the shadow tiles PNGs (see "Alpha blending on monster art" in the Feature Requests forum)

- Gerry


[Edited by trick on 07-14-2003 at 10:45 PM GMT: sentence restructuring =)]

Schik
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trick wrote:
This could also be fixed by making the shadow tiles PNGs

I assume libSDL supports PNG files completely? I'm too lazy to check. Would we have to change what blits we're calling to alpha-aware blits? Or do they all use alpha if it's there?


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ErikH2000
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Schik wrote:

trick wrote:
This could also be fixed by making the shadow tiles PNGs

I assume libSDL supports PNG files completely? I'm too lazy to check. Would we have to change what blits we're calling to alpha-aware blits? Or do they all use alpha if it's there?

I would be happy to switch over to PNG. I don't believe SDL supports the format by itself, but there's code out there that will easily do it ("SDL_Image" comes to mind).

I've found that alpha blits can be pretty slow on low-end computers like mine (333mhz, an unspecial video card), so I think there are some tricks that should be used. But that can be looked at later. It would be simpler to just load in a bunch RGBA surfaces and perform SDL blits with the alpha option, but this makes things much slower.

-Erik

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StuartK
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Schik wrote:

trick wrote:
This could also be fixed by making the shadow tiles PNGs

I assume libSDL supports PNG files completely? I'm too lazy to check. Would we have to change what blits we're calling to alpha-aware blits? Or do they all use alpha if it's there?

Just to make clear (hopefully, if it isn't already) this topic was intended for a seperate issue to the wall/object shadows. In this case, certain creatures and objects have a flag colour which is used to indicate that a 'shadow' is there, at that individual pixel position. When a non-floor square is underneath it does not blend correctly with the shadow (e.g. instead of shadowed tar, or shadowed wall, we always get shadowed floor)

trick
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Schik wrote:
I assume libSDL supports PNG files completely? I'm too lazy to check. Would we have to change what blits we're calling to alpha-aware blits? Or do they all use alpha if it's there?

ErikH2000 wrote:
I would be happy to switch over to PNG. I don't believe SDL supports the format by itself, but there's code out there that will easily do it ("SDL_Image" comes to mind).

Right. SDL itself doesn't support loading PNG directly like BMP, so we'll have to use another library for that. SDL_image works fine and is made ready for use with SDL, or we could simply use libpng directly if that's the only format it'll use - SDL_image would be an extra library requirement, and it would require libpng anyway, but it's nice for supporting a larger range of formats. Up to you

I've found that alpha blits can be pretty slow on low-end computers like mine (333mhz, an unspecial video card), so I think there are some tricks that should be used. But that can be looked at later. It would be simpler to just load in a bunch RGBA surfaces and perform SDL blits with the alpha option, but this makes things much slower.

Is this with RLE acceleration enabled ? That can boost things up considerably.

StuartK wrote:
Just to make clear (hopefully, if it isn't already) this topic was intended for a seperate issue to the wall/object shadows. In this case, certain creatures and objects have a flag colour which is used to indicate that a 'shadow' is there, at that individual pixel position. When a non-floor square is underneath it does not blend correctly with the shadow (e.g. instead of shadowed tar, or shadowed wall, we always get shadowed floor)

Sorry, i didn't mean to hijack your topic. But, if the shadow tiles are converted to PNG (or anything else with an alpha channel, really), this problem would magically go away

- Gerry