Retro low-res games with Gideros

john26

Retro games are often popular, e.g. Orange Pixel games, and they tend to get good coverage in Touch Arcade and other places. In a recent discussion I noted that the iPad has exactly 4 times the resolution of the ZX Spectrum (1024x768). So I was thinking, could a logical resolution of 256x192 be supported in such a way that the game is written relative to 256x192 then pixel quadrupled onto the iPad screen? This pixel quadrupling needs to preserve the original pixels but convert each pixel to a 4x4 block. Thus the iPad screen looks exactly like a Spectrum screen with clearly visible pixels.

This should work with vector graphics as well: if I draw a 45 degree line on the virtual 256x192 screen the "staircase" appearance of the line should be clearly visible. I.e. the line should not be redrawn at higher resolution when in "stretch" mode. Vector images need to be magnified pixel-by-pixel not simply redrawn on a different coordinate system.

Of course the example I gave iPad/Spectrum is just one pairing that might be considered. But the two resolutions should be exact multiples.

cubuspl42

I think that default Gideros (OpenGL) behavior would be making that bitmaps smooth and destroying the effect you expect.
But don't worry about antialiasing of VG (Shape class) - it won't get into your way, it doesn't support any AA at all.

john26

I don't think AA is the issue. Even without AA, when you use stretch scaling I suspect the original pixellation is lost for vector graphics as the original line is simply redrawn (correct me if I am wrong). I want a low-res virtual coordinate system which is pixel quadrupled (or whatever) onto the iPad screen (for example).

Not sure if Gideros can do that? Or even if openGL can do it?

keszegh

what if you make the game for a small resolution but instead of putting it on stage, you render it to a rendertarget and then put this rendertarget on stage as a bitmap and scaling it up. if you turn off filtering for this rendertarget than perhaps after scaling you get the desired pixely effect.
at least the vector shapes etc have a chance to be upscaled in a manner as you wish as when you draw them to a rendertarget, you completely lose the vector info and they are stored pixelwise.
you may want to test this out using a simple example.

cubuspl42

That's a good idea! I'm not sure how about performance of rendering to texture in every single frame. If it's HW accelerated, it should be ok.

keszegh

i guess it should be ok. give us some feedback about your experiments, when you try it out.

john26

@keszegh: I think this is indeed the way to do it, good thinking!

Unless devs have any other ideas?

FlimFlamboyant

Textures aren't filtered by default, so scaling them up will preserve their blockiness. I'm doing this with a retro-style low-res game myself. If you want filtering, you have to activate it per-texture explicitly in Texture.new() or TexturePack.new().

As for the vector-drawing functions, I think you're stuck with the RenderTarget approach. I would keep this to an absolute minimum if I were you, as it's likely to destroy performance.

SinisterSoft

You could render to a texture then bring that texture in as a sprite. There is a bug in some cases when doing this though, Atilim knows about this and said he would do an update soon.