5:4 aspect ratio incorrect in GL renderer

[Doom_user]

The 5:4 aspect ratio in the GL renderer increases the player's vertical viewing area too much. As a result, the player's view of the level gets vertically compressed/scrunched in compared to the 4:3 aspect ratio.

http://img197.imageshack.us/img197/6871/glcomp.png

If it were correct, the 4:3 and 5:4 screenshots would line up exactly, like they do in the software renderer.

http://img143.imageshack.us/img143/4772/softcomp.png

There was an identical bug in PrBoom Plus's GL renderer. The cause was the aspect ratio being entered as 1.2 instead of 1.25.

[Gez]

I'll be honest, I don't understand how aspect ratio works in GZDoom.

There's this table which is apparently used:

Code: Select all

// First column: Base width (unused)
// Second column: Base height (used for wall visibility multiplier)
// Third column: Psprite offset (needed for "tallscreen" modes)
// Fourth column: Width or height multiplier
const int BaseRatioSizes[5][4] =
{
	{  960, 600, 0,                   48 },			//  4:3   320,      200,      multiplied by three
	{ 1280, 450, 0,                   48*3/4 },		// 16:9   426.6667, 150,      multiplied by three
	{ 1152, 500, 0,                   48*5/6 },		// 16:10  386,      166.6667, multiplied by three
	{  960, 600, 0,                   48 },
	{  960, 640, (int)(6.5*FRACUNIT), 48*15/16 }	//  5:4   320,      213.3333, multiplied by three
};

Then there's the problem that I don't get any video modes with a width identical to the single 5:4 mode I have at my disposal. I don't know how to add more modes -- without getting them letterboxed in the screenshots, which makes the comparison impossible. (Though they're curiously not letterboxed in the game window...)

[Graf Zahl]

Please don't ask me how that table is supposed to work. I had to do some alternate calculations because it doesn't make sense so even if there's differences it's very unlikely that it's going to change unless it's something obvious.

[Gez]

Yeah, I don't understand what it does and how it does it.


[spoiler]The only thing I've figured out is that the first column always correspond to the width for a height of 720 in the given resolution (720*4/3 =960, 720*16/9=1280, 720*16/10=1152) except for the 5:4 one where then it would have to be 900. But that column is apparently not used anyway.

Then there's the multiplier.
Base ratio is 4:3.
16:3 => 3/4; 4*4=16; 3*3=9 => 16:9
16:10 => 5/6; 4*6=24; 3*5=15=> 24:15 = 8:5 = 16:10
5:4 => 15/16; 4*16=64; 3*15=45 => 64:45 != 5:4

So if my hunch is correct, it should be 16/15, not 15/16! 4*15=60; 3*16=48 => 60:48 = 5*12:4*12 = 5:4.

16/15 would also make more sense wrt. the second column:
450 = 3/4 * 600
500 = 5/6 * 600
640 = 16/15 * 600

Tell you what, I think I'll upload an experimental build with that change and let Doom_user try it out.[/spoiler]

Doesn't matter, this only affects HUD sprites.


Fixed, it was in gl_scene I ought to have been looking.