spring dampened camera #1589

loveridge · 2024-07-09T16:15:24Z

Adds a new option for spring dampened camera transitions.

https://discord.com/channels/549281623154229250/724924957074915358/1260277856370561145

About a microsecond faster than the old transition mode:

rts/Game/CameraHandler.cpp

rts/System/SpringDampers.cpp

sprunk · 2024-07-10T17:40:25Z

rts/System/SpringDampers.cpp

+
+float spring_damper_damping(float halflife)
+{
+	return halflife_to_damping(halflife) / 2.0f;


Suggested change

return halflife_to_damping(halflife) / 2.0f;

static constepxr float why_halve? = 0.5f;

return halflife_to_damping(halflife) * well_named_constant;

These constants are all related to the derivation of stiffness and damping inputs to a single halflife value. The math is a bit too complicated for me so you'll have to read the guy's blogpost if you want more info. But my take away from it is that we can have a single input value that gives it a more or less "springiness".

sprunk · 2024-07-10T17:42:40Z

rts/Game/CameraHandler.cpp

+
+	timed_spring_damper_exact_vector(currentPos, camTransState.posVelocity, camTransState.startPos,
+		targetPos, camTransState.timeEnd, camTransState.halflife, damping, eydt, dt, 2.0f);


Suggested change

timed_spring_damper_exact_vector(currentPos, camTransState.posVelocity, camTransState.startPos,

targetPos, camTransState.timeEnd, camTransState.halflife, damping, eydt, dt, 2.0f);

static constexpr float APPREHENSION = 2.0f; // value chosen on the basis of XYZ

timed_spring_damper_exact_vector(currentPos, camTransState.posVelocity, camTransState.startPos,

targetPos, camTransState.timeEnd, camTransState.halflife, damping, eydt, dt, APPREHENSION);

Here is what the guy writes about apprehension:

apprehension parameter controls how far into the future we try to track the linear interpolation. A value of 2 means two-times the half life, or that we expect the blend-out to be 75% done by the goal time.

rts/Game/CameraHandler.cpp

sprunk · 2024-07-10T17:54:51Z

The spring damping demo linked as a source shows that it overshoots (0:05s and onwards). Large discrete movements happen often for cameras (move by clicking minimap, selecting important units like ctrl+c that focus the unit, etc.) so this specific behaviour of the spring-damping mode sounds quite undesirable

loveridge · 2024-07-10T18:46:10Z

The spring damping demo linked as a source shows that it overshoots (0:05s and onwards). Large discrete movements happen often for cameras (move by clicking minimap, selecting important units like ctrl+c that focus the unit, etc.) so this specific behaviour of the spring-damping mode sounds quite undesirable

These are specifically the spring functions for a critically dampened spring that should approach the goal without additional oscillations: https://theorangeduck.com/page/spring-roll-call#critical

…hout restart

sprunk · 2024-07-12T00:39:05Z

rts/Game/Camera/FPSController.cpp

@@ -20,7 +20,7 @@ CONFIG(float, FPSFOV).defaultValue(45.0f);
 CONFIG(bool, FPSClampPos).defaultValue(true);


-CFPSController::CFPSController(): oldHeight(300.0f)
+CFPSController::CFPSController(): oldHeight(300.0f), rot(2.677f, 0.0f, 0.0f)


what's 2.677?

Same default as spring camera.

sprunk · 2024-07-12T00:39:22Z

rts/Game/Camera/FPSController.cpp

+	rot.y += mouseScale * move.x;
+	rot.x = std::clamp(rot.x + mouseScale * move.y * move.z, 0.01f, math::PI * 0.99f);


so what's the difference between rot and dir?

rot is the rotation vector, encoding pitch, yaw and roll. dir is the 3d direction vector.

sprunk · 2024-07-13T23:54:31Z

rts/Game/Camera/RotOverheadController.h

@@ -19,16 +19,19 @@ class CRotOverheadController : public CCameraController
 	void MouseWheelMove(float move, const float3& newDir) { MouseWheelMove(move); }

 	void SetPos(const float3& newPos);
+	void SetRot(const float3& newRot) { rot = newRot; };


Does this (and the same for the Spring camera below) mean that passing rot with a non-zero z component nets you a rolled (potentially upside-down etc) camera? Since previously GetRotFromDir always ensured zero z:

spring/rts/Game/Camera.cpp

Line 516 in c183d49

r.z = 0.0f;

Yes, this allows rotatable overhead camera to roll if the newRot has a z component. Unfortunately there is no mechanism to set this in practice, should I add a config value to enable a modifier to roll the camera? Perhaps MOVE_STATE_TLT. And/or set it with SetCameraState.

As for switching to other cameras, the more constrained cameras manage their constraints to prevent rolls. Spring camera does it with float3 GetRot() const { return (float3(rot.x, GetAzimuth(), 0.0f)); }, so the current rot.z has no effect. The rest of the cameras don't override the CameraController SetRot, so they just set the dir and therefore cannot roll. Except for overview camera, which throws out the x and z components.

But in general, if a camera is expected to operate under certain constraints, then it should manage those constraints internally. For example, as overview camera does by throwing out or otherwise constraining the values. And we do see this all over, such as spring camera clamping the rot.x to the 90 degree range of .5pi to pi.

Unfortunately camera rolling breaks a number of other things, so I won't be adding any way for the rotatable overhead camera to be rolled from gameside.

sprunk · 2024-07-13T23:56:53Z

rts/Game/CameraHandler.cpp

@@ -379,6 +569,7 @@ void CCameraHandler::SetCameraMode(unsigned int newMode)
 	CCameraController* newCamCtrl = camControllers[currCamCtrlNum = newMode];

 	newCamCtrl->SetPos(oldCamCtrl->SwitchFrom());
+	newCamCtrl->SetRot(oldCamCtrl->GetRot());


See previous comment, is this a vector to pass a previously-impossible rotation by switching from a less constrained camera to a more constained one?

sprunk · 2024-07-14T15:27:19Z

The PR is now big and scary so I've extracted an uncontroversial part #1598

sprunk · 2024-07-18T13:02:07Z

If the rot refactor involves no logic change on its own then it could also be split off to a separate PR for easier review/merge.

lhog · 2024-10-06T10:57:08Z

Does this look merge-able @sprunk @loveridge ?

sprunk · 2024-10-06T12:46:48Z

It looks fine and I didn't find any obvious code problems, I was just too scared to give a full "Approved" mark.

loveridge · 2024-10-06T17:04:37Z

Does this look merge-able @sprunk @loveridge ?

I'd be happy to get it in

loveridge added 9 commits July 9, 2024 09:03

spring dampened camera

6c9dc1e

skip some calculations

852ae12

space indentation to tabs

80a8aed

Move dampers into their own file

9461d5d

add ClampRads

715ac0d

add timed damper to rotations

7891e8b

smooth old transition code as well

267c835

had a flipped sign

27f6a5d

revert my changes to the original transition mode

aa0ccbc

sprunk reviewed Jul 10, 2024

View reviewed changes

add lerp smoothed transitions

2b2b65a

loveridge added 6 commits July 10, 2024 12:22

PR comments

c5f4887

vastly improved rotation handling

7a2cc83

modify rotoverhead to use an incrementing rot value

407f954

needs a default

eebb0e3

keep rot state for fps camera

54033ce

move edge move config into the camera handler. now can be changed wit…

c2cf464

…hout restart

sprunk reviewed Jul 12, 2024

View reviewed changes

loveridge added 2 commits July 13, 2024 00:35

clean up camera switches

63ddc34

allow negative transition times to do nothing

fc19428

sprunk reviewed Jul 13, 2024

View reviewed changes

loveridge added 3 commits July 14, 2024 10:52

Merge remote-tracking branch 'origin/BAR105' into spring-dampened-camera

710d9a2

update include paths

e71c682

add timeFactor for timed spring dampened camera

4b5fce1

add assert

1ccba77

loveridge mentioned this pull request Oct 6, 2024

Dolly camera #1649

Merged

loveridge closed this Nov 2, 2024

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spring dampened camera #1589

spring dampened camera #1589

loveridge commented Jul 9, 2024 •

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sprunk Jul 10, 2024

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sprunk Jul 13, 2024 •

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loveridge Jul 14, 2024

loveridge Jul 14, 2024

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sprunk commented Jul 14, 2024

sprunk commented Jul 18, 2024

lhog commented Oct 6, 2024

sprunk commented Oct 6, 2024

loveridge commented Oct 6, 2024

	return halflife_to_damping(halflife) / 2.0f;
	static constepxr float why_halve? = 0.5f;
	return halflife_to_damping(halflife) * well_named_constant;


		timed_spring_damper_exact_vector(currentPos, camTransState.posVelocity, camTransState.startPos,
		targetPos, camTransState.timeEnd, camTransState.halflife, damping, eydt, dt, 2.0f);

		rot.y += mouseScale * move.x;
		rot.x = std::clamp(rot.x + mouseScale * move.y * move.z, 0.01f, math::PI * 0.99f);

spring dampened camera #1589

spring dampened camera #1589

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sprunk commented Jul 14, 2024

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lhog commented Oct 6, 2024

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loveridge commented Oct 6, 2024

loveridge commented Jul 9, 2024 •

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sprunk commented Jul 10, 2024 •

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