Precise zooming

[cKomuHKa]

Can I somehow zoom a game screen without blurring it?
Unit sprites are too small for me. I want to increase their size (x2 for example), but I do not want to see blurred pixelart.

[Dugi]

Can I somehow zoom a game screen whithout blurring it?

No, you can't.

You can try a workaround, half your screen resolution and don't zoom.

[iceiceice]

If you are willing to recompile the game from source, you could probably turn off whatever aliasing it is doing, but it doesn't look like you can do that otherwise. Maybe we should add this to 1.14 as an advanced preference or something.

[cKomuHKa]

Maybe we should add this to 1.14 as an advanced preference or something.

That would be great.

[Crow_T]

If you are willing to recompile the game from source, you could probably turn off whatever aliasing it is doing, but it doesn't look like you can do that otherwise. Maybe we should add this to 1.14 as an advanced preference or something.

+1 to user preference, and as a side note how does one turn the anti-aliasing off in the source?

[iceiceice]

Let me emphasize that I use the word "probably" because I don't know for a fact that you can.

Spoiler:

But when I made a different game like 10 years ago using openGL, I remember that part of the setup for openGL was selecting from the anti-aliasing options for how textures are rendered in 3d, there was some library call for it. I think that generally, anti-aliasing stuff is handled at that layer of the graphics system, and I assume that there's similar options when using SDL.

Note that, on master branch we are in some interim state where we are using SDL_gpu for graphics now, and not SDL v 1.2 as we always have, and we may or may not change again to something like SDL 2 on master branch before 1.14 is released. (See lipkab's forum post about this.) So bottom line, I would definitely not attempt this on master branch, instead you should base the tweaks on 1.12 branch if you wanted to do this.

So if you wanted to adjust this kind of stuff in the source, I think what I would do is, go on the web, and search through the SDL api to figure out what statements control anti-aliasing / "smoothing" / whatever they call it, then try to grep through the wesnoth src directory and see if you can find any instances of those. With luck you'll find some, then you can read the api carefully and tweak stuff to your hearts content. Note: this is pretty speculative, not for the faint of heart, and there are no guarantees that you'll get quite what you want.

Edit: Okay, actually I got curious and decided to peek at the code and see if my educated guess was right. Turns it out was *not*, you probably cannot easily do this... so you might want to just forget I ever mentioned it

Spoiler:

We don't actually use any built-in library scaling function in wesnoth 1.12, we appear to have our own custom scaling function which I guess was optimized to make our content look better. I think that is what is happening here: https://github.com/wesnoth/wesnoth/blob ... s.cpp#L409

To be completely honest, I don't really understand why, if you zoom to the level so that a unit is about the same size as its sprite image, that you get significant blur at all, I would think it should be nearly sharp. So either this is an artifact of our scaling algorithm in the ranges that it was not intended for, or it's just that it's really hard to get the zoom level set almost exactly so that there is no scaling occuring. But tbh I couldn't really tell you right now why you are seeing blurs like in your image.

[iceiceice]

Okay, actually I had another idea about this and came back to it, one thing lead to another, I think I can tell you at least one way that seems to work now. No promises that it's really doing the right thing, but it seems to give that chunky, no blur feel.

It requires source code modifications, but they are quite small, just changing 3 lines. You can do it yourself, or I provide a patch file below (but you need to figure out how to use some tool to apply it then, so pick your poison.)

Edit: The patch is now moot, see next post.

patch

All of the below is based on 1.12 branch at git revision 34b383a.

There's two steps:
1. Increase the default zoom value by a multiple.

Spoiler:

In src/display.cpp, change the one line with Default Zoom:

Code: Select all

namespace {
	const int DefaultZoom = game_config::tile_size;
	const int SmallZoom   = DefaultZoom / 2;

	const int MinZoom = 4;
	const int MaxZoom = 200;
	size_t sunset_delay = 0;

	bool benchmark = false;

	bool debug_foreground = false;
}

The one line with DefaultZoom should be changed. It is normally 72. It should be either 144 or 288, for 2x or 4x zoom, I get good results either way.

Should look like:

Code: Select all

namespace {
	const int DefaultZoom = 144; //game_config::tile_size;
	const int SmallZoom   = DefaultZoom / 2;

	const int MinZoom = 4;
	const int MaxZoom = 200;
	size_t sunset_delay = 0;

	bool benchmark = false;

	bool debug_foreground = false;
}

(Note that game_config::tile_size is used in other places, and I find that if you change that instead it doesn't end up zooming. Not sure why but this is definitely a hack.)

2. Disable the bilinear interpolation, by setting the neighborhood size to always be a single pixel.

Spoiler:

In src/sdl_utils.cpp, change two lines, in function scale_surface, at lines 457, 458 in this revision, so that the variables dx and dy are always zero:

This

Code: Select all

				const Uint32* const src_word = src_pixels + ysrcint*src->w + xsrcint;
				Uint32* const dst_word = dst_pixels +    ydst*dst->w + xdst;
				const int dx = (xsrcint + 1 < src->w) ? 1 : 0;
				const int dy = (ysrcint + 1 < src->h) ? src->w : 0;

should become

Code: Select all

				const Uint32* const src_word = src_pixels + ysrcint*src->w + xsrcint;
				Uint32* const dst_word = dst_pixels +    ydst*dst->w + xdst;
				const int dx = 0; //(xsrcint + 1 < src->w) ? 1 : 0;
				const int dy = 0; //(ysrcint + 1 < src->h) ? src->w : 0;

Results:

http://imgur.com/a/A5dc7#0

You can definitely notice the increased chunkiness on the Drake leaders. Also, I think the horseman looks more like what you were saying. Also the skeleton archer bowstring looks especially nice.

If you zoom out with this version, it will definitely look much worse because there will be no blending at all... because the patch changes the default zoom value, if you click in the upper right on the magnifying glass, it will zoom back to whatever your preferred settings (144 or 288) was.

Patch:

As an alternative you can use this patch file instead of modifying the source by hand.

patch

Download the .patch file which I have attached to this thread, and place it at the root of your wesnoth repo. (So, in the folder "wesnoth". If you don't have a repo, follow these instructions: WesnothRepository#Download.)

For best results use it as follows: ($ is your prompt, you type that line, the following lines are git's response)

If you don't have git, you can try to apply it using another program to whatever 1.11.x or 1.12.x source you have, but there are no guarantees that it will apply smoothly at a different revision. I'm going to assume here that you are using git.

$ git checkout 34b383a
[spoiler]Note: checking out '34b383a'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

git checkout -b new_branch_name

HEAD is now at 34b383a... update changelog[/spoiler]
$ git status
[spoiler]HEAD detached at 34b383a
Untracked files:
(use "git add <file>..." to include in what will be committed)

0001-Default-zoom-factor-x2-and-disable-bilinear-interpol.patch[/spoiler]
$ git apply 0001-Default-zoom-factor-x2-and-disable-bilinear-interpol.patch
$ git status
[spoiler]HEAD detached at 34b383a
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)

modified: src/display.cpp
modified: src/sdl_utils.cpp

Untracked files:
(use "git add <file>..." to include in what will be committed)

0001-Default-zoom-factor-x2-and-disable-bilinear-interpol.patch[/spoiler]

Now you can compile and run wesnoth.

[iceiceice]

Update:

It was eventually decided that the blurry behavior when you zoom in is considered a bug. It has now been fixed, the above patch is no longer necessary, you will get results such as that by default instead.

Commit: https://github.com/wesnoth/wesnoth/comm ... a437a2920d