[ZH] Adjust field of view based on aspect ratio #518

valeronm · 2025-03-26T20:03:43Z

The game doesn't support wide screens well because it has static horizontal field of view (FOV) and static maximum camera height. This means that for every resolution, the camera shows the same horizontal amount of terrain, but the vertical field of view becomes narrower for wider resolutions. So on wide screens, we get a center crop of what is visible on 4:3 resolutions (screenshots below).
To support wider screens, we need to have constant vertical FOV and calculate horizontal FOV based on the screen aspect ratio.

Changes

Added function W3DView::adjustFovToAspectRatio which is called every time when display resolution changes;
Function adjustFovToAspectRatio changes camera FOV differently based on aspect ratio:
- when screen is wider than 4:3 it sets the fixed vertical FOV based on vFOV used for 4:3 screens (38.55°);
- when screen narrower than 4:3 but still horizontal, it sets fixed hFOV used for 4:3 screens (50°) - this is what the game always uses now;
- for portrait screens it uses varying 50° to 60° vFOV

Screenshots

1600 x 1200 - 4:3 (original)

1600 x 900 - 16:9 (original)

1600 x 900 - 16:9 (new logic)

3200 x 900 - 32:9 (new logic)

900 x 1600 - 9:16 (new logic)

Fixes #78
Depends on #460 to make wide resolutions selectable

ElTioRata · 2025-03-26T22:55:08Z

Can I ask why do you get less horizontal FOV on 9:16 compared to 4:3?

DevGeniusCode · 2025-03-26T23:39:17Z

Is the PR only for Zero Hour? Because I see changes in Generals too.

valeronm · 2025-03-27T02:03:05Z

Can I ask why do you get less horizontal FOV on 9:16 compared to 4:3?

This is done on purpose. The same horizontal FOV will allow seeing almost the entire map in portrait mode. I'm sure this is not an ideal fix for portrait modes, but it should be good enough until a better solution is implemented. One possible solution is to change the angle of the camera towards the terrain for portrait screens.

900 x 1600 with fixed hFOV used for 4:3 screens

Is the PR only for Zero Hour? Because I see changes in Generals too.

This PR depends on #460, so the current branch contains one commit from that PR, which includes changes for both Generals and Zero Hour. After merging #460, this PR will have changes for Zero Hour only.

ElTioRata · 2025-03-27T17:13:34Z

The same horizontal FOV will allow seeing almost the entire map in portrait mode.

Out of curiosity, how does it look on 1:1?

valeronm · 2025-03-27T17:23:37Z

Out of curiosity, how does it look on 1:1?

I've made the spreadsheet with original and FOV values and also made the folder with screenshots for different aspect ratios.

OmniBlade · 2025-03-28T14:05:48Z

Can I ask why do you get less horizontal FOV on 9:16 compared to 4:3?

This is done on purpose. The same horizontal FOV will allow seeing almost the entire map in portrait mode. I'm sure this is not an ideal fix for portrait modes, but it should be good enough until a better solution is implemented. One possible solution is to change the angle of the camera towards the terrain for portrait screens.
900 x 1600 with fixed hFOV used for 4:3 screens

If you are playing on your phone maybe you need this :D

…Hackers#518)

xezon

I have reservations about scaling FOV like this. On the 32:9 sample image we can see the extreme view distortion towards the left and right edges, where the trees no longer stand straight.

I suggest to move some units to these edges and then check how distorted these will look.

My first instinct here is to primarily scale camera height, not just the FOV. Maybe it can be a mix of both. GenTool only scales the camera height. Mods only scale camera height as well (via GameData.ini). There is no precedent to scaling this with FOV.

We need to test this change to see how this looks in action.

xezon · 2025-07-01T08:48:26Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

@@ -226,10 +226,48 @@ void W3DView::setWidth(Int width)
 	m_3DCamera->Get_Viewport(vMin,vMax);
 	vMax.X=(Real)(m_originX+width)/(Real)TheDisplay->getWidth();
 	m_3DCamera->Set_Viewport(vMin,vMax);
+}
+
+// TheSuperHackers @tweak valeronm 25/03/2025 Adjusting FOV to look similar to what we have in in 4:3 (hFOV: 50, vFOV 38.55)


xezon · 2025-07-01T08:48:37Z

GeneralsMD/Code/GameEngineDevice/Include/W3DDevice/GameClient/W3DView.h

@@ -232,7 +232,7 @@ class W3DView : public View, public SubsystemInterface

 	virtual void setGuardBandBias( const Coord2D *gb ) { m_guardBandBias.x = gb->x; m_guardBandBias.y = gb->y; }

-
+	virtual void adjustFovToAspectRatio(const Int width, const Int height);
 private:


add blank line before this

xezon · 2025-07-01T08:49:06Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+void W3DView::adjustFovToAspectRatio(const Int width, const Int height)
+{
+	static const Real fixedHFOV = 50.00f;
+	static const Real fixedVFOV = 38.55f;


Use CONSTEXPR instead of static

xezon · 2025-07-01T08:50:38Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+		// Wider than 4:3 resolutions get fixed vFOV 38.55
+		vFOVRad = DEG_TO_RADF(fixedVFOV);
+		hFOVRad = 2.0f * atan(tan(vFOVRad / 2.0f) * aspectRatio);
+		drawEntireTerrain = true;


This looks suspicious. The GenTool implementation did not need this for up to 16:9. The original game also did not need this for 4:3. It will affect performance.

xezon · 2025-07-01T09:08:35Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+void W3DView::adjustFovToAspectRatio(const Int width, const Int height)
+{
+	static const Real fixedHFOV = 50.00f;
+	static const Real fixedVFOV = 38.55f;


How did the magical 38.55 come to be?

xezon · 2025-07-01T09:16:25Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+	else
+	{
+		// Portrait resolutions get fixed vFOV adjusted to aspect ratio
+		// vFOV increases from 50.0 for 1:1 to 60.0 for 9:21 and then fixed 60.0


What is the reason for this fine tuning?

xezon · 2025-07-01T10:03:16Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+	Bool drawEntireTerrain = false;
+	if (aspectRatio >= 4.0f / 3.0f)
+	{
+		// Wider than 4:3 resolutions get fixed vFOV 38.55


This comment repeats the code value that is assigned to fixedVFOV. This means the commented value can go out of sync when someone changes the code value. Prefer not baking values into comments, unless they definitely never change.

xezon · 2025-07-01T10:05:49Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+	const Real aspectRatio = static_cast<Real>(width)/ static_cast<Real>(height);
+	Real vFOVRad, hFOVRad;
+	Bool drawEntireTerrain = false;
+	if (aspectRatio >= 4.0f / 3.0f)


For Multiplayer, I very much prefer we cap this at max 16/9, min 9/16, to not give these ultra screens a massive advantage, preferably configurable in GameData.ini, so that Mods can do their own setups.

For Singleplayer and Replay it is fine to go wide with no limits.

xezon · 2025-07-01T10:28:03Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+	{
+		// Wider than 4:3 resolutions get fixed vFOV 38.55
+		vFOVRad = DEG_TO_RADF(fixedVFOV);
+		hFOVRad = 2.0f * atan(tan(vFOVRad / 2.0f) * aspectRatio);


I would not mind a brief explanation in a comment for the math how the fov is scaled.

xezon · 2025-07-01T10:30:38Z

GeneralsMD/Code/GameEngineDevice/Source/W3DDevice/GameClient/W3DView.cpp

+	{
+		// Narrower than 4:3 but not yet portrait resolutions get fixed hFOV 50.0
+		hFOVRad = DEG_TO_RADF(fixedHFOV);
+		vFOVRad = 2.0f * atan(tan(hFOVRad / 2.0f) / aspectRatio);


Is there no cut in fov'ness between the different conditions? How does this work?

xezon · 2025-07-01T17:26:22Z

Review

I tested this change in 32:9 and it causes way too much distortion at the far edges.

Check how this Overlord distorts near the edge

Suggestion

I suggest to refine this implementation, to not just offer Camera Fov adjustment for Resolution, but also Camera Height adjustment for Resolution.

Then, provide a scalar to scale the Camera Fov & Height adjustments.

So for example, CameraFovWeightForAspectRatioAdjustment = 0.4 would mean 40% adjustment comes from Fov, and 60% adjustment comes from Height. This way we can tweak the desired view distortion level and keep it small.

ElTioRata · 2025-07-01T19:42:10Z

I don't see any screen distortion at 16:9 though. My suggestion would be to get the game to start increasing the camera height value when using wider screen proportions than 16:9.

xezon · 2025-07-02T06:34:52Z

I don't see any screen distortion at 16:9 though. My suggestion would be to get the game to start increasing the camera height value when using wider screen proportions than 16:9.

Distortion in 16:9 will be much smaller, but it is still there. It is not great to make the logic ever more complicated with more aspect ratio conditions.

The 4:3 is our reference condition. The only fixed requirement is that the camera height and fov at 4:3 is unchanged. From there, make it as simple as possible.

Mauller · 2025-07-02T07:39:13Z

From what i remember seeing, the camera height is currently calculated off the horizontal screen resolution.

This likely wants scaling related to 800x600 and changing to be based off the min of the horizontal or vertical resolution, this should then correct the zoomed in look on wider resolutions while keeping the same FoV. This can then act as a starting basis for any other kind of increases in camera height in future.

valeronm changed the title ~~Adjust field of view based on aspect ratio~~ [ZH] Adjust field of view based on aspect ratio Mar 26, 2025

DevGeniusCode added Bug Something is not working right, typically is user facing Critical Severity: Minor < Major < Critical < Blocker ZH Relates to Zero Hour labels Mar 26, 2025

valeronm force-pushed the adjust_field_of_view_to_aspect_ratio branch from 7651a21 to cb3225e Compare March 27, 2025 01:09

valeronm added a commit to valeronm/GeneralsGameCode that referenced this pull request Mar 30, 2025

[ZH] Adjust field of view for differnt from 4:3 resolutions (TheSuper…

c52e1e8

…Hackers#518)

valeronm force-pushed the adjust_field_of_view_to_aspect_ratio branch from cb3225e to c52e1e8 Compare March 30, 2025 00:03

valeronm added a commit to valeronm/GeneralsGameCode that referenced this pull request Apr 17, 2025

[ZH] Adjust field of view for differnt from 4:3 resolutions (TheSuper…

74e96ed

…Hackers#518)

valeronm force-pushed the adjust_field_of_view_to_aspect_ratio branch from c52e1e8 to 74e96ed Compare April 17, 2025 08:12

xezon mentioned this pull request May 13, 2025

Replicate relevant GenTool fixes and improvements #850

Open

32 tasks

[ZH] Adjust field of view for differnt from 4:3 resolutions (TheSuper…

07c1097

…Hackers#518)

valeronm force-pushed the adjust_field_of_view_to_aspect_ratio branch from 74e96ed to 07c1097 Compare June 30, 2025 22:03

xezon added Design Is a matter of game design Enhancement Is new feature or request Gen Relates to Generals and removed Bug Something is not working right, typically is user facing labels Jul 1, 2025

xezon added this to the Important features milestone Jul 1, 2025

xezon reviewed Jul 1, 2025

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[ZH] Adjust field of view based on aspect ratio #518

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[ZH] Adjust field of view based on aspect ratio #518

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valeronm commented Mar 26, 2025

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