Old style 8bit gfx with clip colour on Iphone ?

Apprentice
Posts: 6
Joined: 2009.11
Post: #1
Hi folks,

I have a question, sicne I am currently doing R&D for our next project: can I (artist) use good old school Amiga-like 32-256 colour bitmaps and define a clip colour for iPhone game development, or does it all have to be 16/24/32bit ?
I love doing pixel art and would like to use those skills...

Thaks,
Emmanuel
[url]www.emme1973.blogspot.comNinja[/url]
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Sage
Posts: 1,482
Joined: 2002.09
Post: #2
Not quite sure what a clip color is exactly. You mean like using magenta or cyan as a color key for transparency? You can trivially generate an alpha value for each pixel at load time for a color key like that.

As for your other question, I'd just like to point out that you can store a 32 color bitmap in a 32bit per pixel png file. You don't have to use all of the millions of colors, and by using only 32 images will compress very well.

Scott Lembcke - Howling Moon Software
Author of Chipmunk Physics - A fast and simple rigid body physics library in C.
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Moderator
Posts: 3,571
Joined: 2003.06
Post: #3
I think I'd just do my graphics in my editor of choice (p-shop, gimp, etc.) using whatever old-school restrictive palette and simply save them as 32-bit files on output.
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Sage
Posts: 1,232
Joined: 2002.10
Post: #4
Emme73 Wrote:can I (artist) use good old school Amiga-like 32-256 colour bitmaps and define a clip colour for iPhone game development

The iPhone supports OES_compressed_paletted_texture, which lets you upload 4 or 8 bit indexed images, with a 16 or 256 color palette defined as 4444, 5551, 8888, 565, or 888 colors.

Those formats aren't natively texturable though, so they are immediately converted to real 4444, 5551, 8888, or 565 textures. You can also use luminance8, alpha8, or luminance8_alpha8 textures.

This means old-school tricks like palette cycling are generally not feasible. But if you want to generate your art as 16 or 256 color indexed bitmaps, OpenGLES will accept it in that format.
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Member
Posts: 351
Joined: 2002.04
Post: #5
Hey Emmanuel, C64-Amiga era is my favourite era of games, I can't wait to see what you come up with!

Just wanted to mention that the iPhone/iPod touch screen is 160dpi rather than the 72dpi of most monitors. This is important because any awesome pixel artwork you do will appear smaller on the iDevice screen than your monitor, and some details get a bit lost.

I was just tweeting the other day about how awesome it would be to see some Bitmap Brothers' games ported to the iDevices. I'd go nuts for The Chaos Engine or Speedball 2 with online multiplayer!
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Apprentice
Posts: 6
Joined: 2009.11
Post: #6
Hi folks, sorry for the late reply Smile
Thank You very much for the tips and answers, I already feared it wouldnt be that straight.But there seem to be ways.I really wanted to save on memory and use that "old school" technique which I am familiar with.

@monteboyd:
My thoughts exactly (large grin...)
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Sage
Posts: 1,482
Joined: 2002.09
Post: #7
No no. It's really not that hard at all.

It's trivial to convert an image that uses a transparent color to have real transparency at load time. Like seriously 10 lines of code probably. As for using low color paletted images, it's trivial to convert these images to PNGs without losing any information.

As for saving memory, why bother? Even if the game is "wasteful" but still loads in under a second or two why bother spending more effort to use a fraction of the resources. The iPhone is still powerful enough that you can be pretty wasteful and still get perfect framerates and fast load times.

Scott Lembcke - Howling Moon Software
Author of Chipmunk Physics - A fast and simple rigid body physics library in C.
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Apprentice
Posts: 6
Joined: 2009.11
Post: #8
Hi,

ok, we will try then Smile
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