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First-Person Camera Controller

Summary#

The FirstPersonCameraController controls a camera as if from a person walking around on a ground plane. The camera is moved via Position and oriented via Yaw and Pitch. Movement is parallel to the plane orthogonal to the given WorldUp direction.

  • Adjusting Position moves the camera through space.
  • Adjusting Yaw rotates the camera left or right around the WorldUp axis;
  • Adjusting Pitch tilts the camera up or down.

Pitch is automatically clamped to ±90° each frame so the camera never flips upside-down.

Example Usage#

// One time setup:
var controller = camera.CreateController<FirstPersonCameraController>(); // (1)!
controller.WorldUp = Direction.Up; // (2)!

// Per-frame:
controller.AdjustAllViaDefaultControls(input.KeyboardAndMouse, deltaTime); // (3)!
controller.AdjustAllViaDefaultControls(input.GameControllersCombined, deltaTime); // (4)!
controller.Progress(deltaTime); // (5)!
  1. This creates the controller, attached to the given camera.

  2. This sets the up direction of the camera. When Pitch is increased, the camera will tilt towards this direction. Movement will be constrained to be parallel to the plane that is orthogonal to this direction.

  3. This manipulates the camera according to the default keyboard and mouse scheme. The position/yaw/pitch properties will change according to any registered user inputs for this frame.

    You can replace this with more specific control code if desired (see below); or remove it entirely if you do not wish to allow user keyboard/mouse input control.

  4. This manipulates the camera according to the default game controller scheme for all game controllers combined. The position/yaw/pitch properties will change according to any registered user inputs for this frame.

    You can replace this with more specific control code if desired (see below); or remove it entirely if you do not wish to allow user gamepad input control.

  5. Calling Progress() once per frame is required on all camera controllers in order for them to actually alter their target Camera's parameters.

Properties#

Per-Frame Targets#

Position

Sets the location of the camera in the world.

Defaults to Location.Origin.

Yaw

Sets the left/right turn amount of the camera.

Increasing this value turns the camera to the left; decreasing to the right.

Defaults to 0°.

Pitch

Sets the up/down turn amount of the camera.

A value of 0° means the camera is looking horizontally; positive values tilt upward, negative values tilt downward.

Pitch is automatically clamped to ±90° during Progress() so that the camera never flips upside-down.

Defaults to 0°.

Configuration#

WorldUp

The "up" direction for this camera.

Changing Yaw rotates the camera around this direction.

Increasing Pitch tilts the camera towards this direction, decreasing it tilts the camera in the opposite direction.

Movement adjustments are projected onto a plane with this direction as its normal.

Defaults to Direction.Up.

Reacting to Input#

As camera controllers are often meant to be affected by user input, there are some convenience methods supplied for controlling the primary per-frame target properties:

Adjusting Pitch#

Keyboard / Mouse#

AdjustPitchViaMouseCursor(...)

Adjusts Pitch according to the captured mouse cursor movement for this frame.

The axis sets which cursor movement direction will be used (defaults to Y, e.g. up/down).

The adjustmentPerPixel value is the angle to add to Pitch for each pixel moved according to the given axis. If null, DefaultPitchSensitivityMouseCursor will be used.

If invertMouseControl is true, the calculated adjustment will be reversed.

AdjustPitchViaMouseWheel(...)

Adjusts Pitch according to the captured mouse wheel movement for this frame.

The adjustmentPerWheelIncrement value is the angle to add to Pitch for each scroll increment on the mouse wheel. If null, DefaultPitchSensitivityMouseWheel will be used.

If invertMouseControl is true, the calculated adjustment will be reversed.

AdjustPitchViaKeyPress(...)

Adjusts Pitch according to whether a certain key is depressed for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The keyToTestFor is the key that, when pressed, will adjust this property.

If reverse is true, the calculated adjustment will be reversed. Defaults to false. This parameter lets you specify two keys in a pair that mirror each other by invoking this method twice (once with reverse as false and once with reverse as true).

The adjustmentPerSec value is the angle to add to Pitch for each second this key is depressed. If null, DefaultPitchSensitivityKeyOrButtonPress will be used.

Gamepad#

AdjustPitchViaControllerStick(...)

Adjusts Pitch according to the captured controller stick position for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The axis sets which stick movement direction will be used (defaults to Y, e.g. up/down).

The maxAdjustmentPerSec value is the angle to add to Pitch when the stick is fully displaced along the given axis. If null, DefaultPitchSensitivityControllerStick will be used.

If useLeftStick is true, the left controller stick will be measured; otherwise the right stick will be measured. Defaults to false.

If invertStickControl is true, the calculated adjustment will be reversed.

AdjustPitchViaControllerTriggers(...)

Adjusts Pitch according to the captured controller trigger positions for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The maxAdjustmentPerSec value is the angle to add to Pitch when the trigger is fully displaced. If null, DefaultPitchSensitivityControllerTrigger will be used.

If rightTriggerPitchesUp is true, the right trigger will pitch up and the left trigger pitch down; otherwise these directions will be reversed. Defaults to true.

AdjustPitchViaButtonPress(...)

Adjusts Pitch according to whether a certain button is depressed for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The buttonToTestFor is the button that, when pressed, will adjust this property.

If reverse is true, the calculated adjustment will be reversed. Defaults to false. This parameter lets you specify two buttons in a pair that mirror each other by invoking this method twice (once with reverse as false and once with reverse as true).

The adjustmentPerSec value is the angle to add to Pitch for each second this button is depressed. If null, DefaultPitchSensitivityKeyOrButtonPress will be used.

Other#

AdjustPitch(...)

Adjusts Pitch according to the given turn rate (adjustmentPerSec) and time step (deltaTime).

This method does not inspect any user input data but is provided as a convenience for building custom per-frame control code.

Adjusting Yaw#

Keyboard / Mouse#

AdjustYawViaMouseCursor(...)

Adjusts Yaw according to the captured mouse cursor movement for this frame.

The axis sets which cursor movement direction will be used (defaults to X, e.g. left/right).

The adjustmentPerPixel value is the angle to add to Yaw for each pixel moved according to the given axis. If null, DefaultYawSensitivityMouseCursor will be used.

If invertMouseControl is true, the calculated adjustment will be reversed.

AdjustYawViaMouseWheel(...)

Adjusts Yaw according to the captured mouse wheel movement for this frame.

The adjustmentPerWheelIncrement value is the angle to add to Yaw for each scroll increment on the mouse wheel. If null, DefaultYawSensitivityMouseWheel will be used.

If invertMouseControl is true, the calculated adjustment will be reversed.

AdjustYawViaKeyPress(...)

Adjusts Yaw according to whether a certain key is depressed for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The keyToTestFor is the key that, when pressed, will adjust this property.

If reverse is true, the calculated adjustment will be reversed. Defaults to false. This parameter lets you specify two keys in a pair that mirror each other by invoking this method twice (once with reverse as false and once with reverse as true).

The adjustmentPerSec value is the angle to add to Yaw for each second this key is depressed. If null, DefaultYawSensitivityKeyOrButtonPress will be used.

Gamepad#

AdjustYawViaControllerStick(...)

Adjusts Yaw according to the captured controller stick position for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The axis sets which stick movement direction will be used (defaults to X, e.g. left/right).

The maxAdjustmentPerSec value is the angle to add to Yaw when the stick is fully displaced along the given axis. If null, DefaultYawSensitivityControllerStick will be used.

If useLeftStick is true, the left controller stick will be measured; otherwise the right stick will be measured. Defaults to false.

If invertStickControl is true, the calculated adjustment will be reversed.

AdjustYawViaControllerTriggers(...)

Adjusts Yaw according to the captured controller trigger positions for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The maxAdjustmentPerSec value is the angle to add to Yaw when the trigger is fully displaced. If null, DefaultYawSensitivityControllerTrigger will be used.

If leftTriggerYawsLeft is true, the left trigger will yaw left and the right trigger yaw right; otherwise these directions will be reversed. Defaults to true.

AdjustYawViaButtonPress(...)

Adjusts Yaw according to whether a certain button is depressed for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The buttonToTestFor is the button that, when pressed, will adjust this property.

If reverse is true, the calculated adjustment will be reversed. Defaults to false. This parameter lets you specify two buttons in a pair that mirror each other by invoking this method twice (once with reverse as false and once with reverse as true).

The adjustmentPerSec value is the angle to add to Yaw for each second this button is depressed. If null, DefaultYawSensitivityKeyOrButtonPress will be used.

Other#

AdjustYaw(...)

Adjusts Yaw according to the given turn rate (adjustmentPerSec) and time step (deltaTime).

This method does not inspect any user input data but is provided as a convenience for building custom per-frame control code.

Adjusting Position#

Position adjustments are constrained to be orthogonal to WorldUp and are specified using either an Orientation2D (e.g. Up/Down/Left/Right etc.) or a polar Angle.

If specifying an orientation, it is interpreted relative to the camera's current view direction (e.g. Up always points camera-forward (orthogonalized against WorldUp), Left always points camera-left (orthogonalized against WorldUp), etc).

If specifying an angle, it is interpreted as a polar angle (e.g. 0° points camera-right (orthogonalized against WorldUp), 90° points camera-forward (orthogonalized against WorldUp), etc).

Keyboard / Mouse#

AdjustPositionViaMouseCursor(...)

Adjusts Position according to the captured mouse cursor movement for this frame.

The axis sets which cursor movement direction will be used (defaults to X, e.g. left/right). When axis is X, motion is along the camera's right; when Y, motion is along the camera's forward.

The distancePerPixel value is the distance (in world units) to move for each pixel of cursor movement. If null, DefaultPositionSensitivityMouseCursor will be used.

If invertMouseControl is true, the calculated adjustment will be reversed.

AdjustPositionViaMouseWheel(...)

Adjusts Position according to the captured mouse wheel movement for this frame.

The positiveOrientation parameter sets which direction the camera moves when the wheel is scrolled forward (defaults to Orientation2D.Up, i.e. the camera's forward direction).

The distancePerWheelIncrement value is the distance (in world units) to move per scroll increment. If null, DefaultPositionSensitivityMouseWheel will be used.

If invertMouseControl is true, the calculated adjustment will be reversed.

AdjustPositionViaKeyPress(...)

Adjusts Position according to whether a certain key is depressed for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The keyToTestFor is the key that, when pressed, will move the camera.

The orientation (an Orientation2D) is the direction in which the camera will move when the key is depressed.

The speed value is the distance per second to move while the key is depressed. If null, DefaultPositionSensitivityKeyOrButtonPress will be used.

Gamepad#

AdjustPositionViaControllerStick(...)

Adjusts Position according to the captured controller stick position for this frame.

The stick's polar angle is used to determine which direction (in Orientation2D space) to move; the stick's displacement scales the speed.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The maxSpeed value is the maximum distance per second when the stick is fully displaced. If null, DefaultPositionSensitivityControllerStick will be used.

If useLeftStick is true, the left controller stick will be measured; otherwise the right stick will be measured. Defaults to true.

AdjustPositionViaControllerTriggers(...)

Adjusts Position according to the captured controller trigger positions for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The positiveOrientation parameter sets which direction the camera moves when the "positive" trigger is held (defaults to Orientation2D.Up).

The maxSpeed value is the maximum distance per second when the trigger is fully displaced. If null, DefaultPositionSensitivityControllerTrigger will be used.

If leftTriggerMovesPositive is true, the left trigger will move in positiveOrientation and the right trigger in the opposite direction; otherwise these directions will be reversed. Defaults to true.

AdjustPositionViaButtonPress(...)

Adjusts Position according to whether a certain button is depressed for this frame.

The deltaTime value is expected to be the time in seconds of this frame iteration.

The buttonToTestFor is the button that, when pressed, will move the camera.

The orientation (an Orientation2D) is the direction in which the camera will move when the button is depressed.

The speed value is the distance per second to move while the button is depressed. If null, DefaultPositionSensitivityKeyOrButtonPress will be used.

Other#

AdjustPosition(...)

Several overloads are provided to directly adjust Position without inspecting any user input data, for building custom per-frame control code:

  • AdjustPosition(Angle polarOrientation, float distance) — moves a fixed distance along the given polar angle (relative to the camera's forward on the ground plane).
  • AdjustPosition(Angle polarOrientation, float moveSpeed, float deltaTime) — speed/time-based version of the above.
  • AdjustPosition(Orientation2D orientation, float distance) — moves a fixed distance in the given orientation.
  • AdjustPosition(Orientation2D orientation, float moveSpeed, float deltaTime) — speed/time-based version of the above.

Default Controls#

The following snippets show the implementation of AdjustAllViaDefaultControls(...) for keyboard/mouse and gamepad respectively:

// AdjustAllViaDefaultControls(input.KeyboardAndMouse, deltaTime):

AdjustPitchViaMouseCursor(input, pitchAdjustmentPerPixel, invertMouseControl: invertPitchControl);
AdjustYawViaMouseCursor(input, yawAdjustmentPerPixel, invertMouseControl: invertYawControl);

AdjustPositionViaKeyPress(input, deltaTime, KeyboardOrMouseKey.ArrowLeft, Orientation2D.Left, moveSpeed);
AdjustPositionViaKeyPress(input, deltaTime, KeyboardOrMouseKey.ArrowRight, Orientation2D.Right, moveSpeed);
AdjustPositionViaKeyPress(input, deltaTime, KeyboardOrMouseKey.ArrowUp, Orientation2D.Up, moveSpeed);
AdjustPositionViaKeyPress(input, deltaTime, KeyboardOrMouseKey.ArrowDown, Orientation2D.Down, moveSpeed);

// AdjustAllViaDefaultControls(input.GameControllersCombined, deltaTime):

AdjustPitchViaControllerStick(input, deltaTime, maxPitchAdjustmentPerSec, invertStickControl: invertPitchControl);
AdjustYawViaControllerStick(input, deltaTime, maxYawAdjustmentPerSec, invertStickControl: invertYawControl);

AdjustPositionViaControllerStick(input, deltaTime, maxMoveSpeed);

Smoothing#

Smoothing changes how quickly the controller adjusts the camera to match the current target properties.

The Position, Yaw, and Pitch target properties can have smoothing applied. Note that Yaw and Pitch share a single RotationSmoothingStrength setting — they cannot be smoothed independently of one another.

// Set properties' smoothing individually:
controller.PositionSmoothingStrength = Strength.VeryMild;
controller.RotationSmoothingStrength = Strength.VeryMild; // Applies to both Yaw and Pitch

// Set all properties' smoothing simutaneously:
controller.SetGlobalSmoothing(Strength.VeryMild);

The default smoothing for all properties is VeryMild. You can choose from VeryMild, Mild, Moderate, Strong, VeryStrong, or None.

  • Smoothing makes the camera feel more 'real' or physical.
  • Higher strengths increase this feeling but also increase the latency between setting a target value and the camera actually meeting that target.
  • Setting the smoothing to None disables smoothing entirely. This means the camera will always be updated to meet exactly the target value of each property on each frame; reducing latency to 0 but making the camera feel less physical.
Custom Smoothing Values

If the enum-based approach is not specific enough for your needs, every property can instead have a custom smoothing strength applied via a method named like "SetCustom[...]SmoothingStrength".

This method takes a single float parameter that indicates the half-life of decay between the current value of a property and its target value.

For example, if the current value of X is 50 and the target value of X is 100, a half-life of 1f would move X to 75 after one second, and then 87.5 after the next second, and so-on.

Advanced: Smoothing is implemented via critically-damped spring. The smoothingHalfLife parameter is translated to become the Ω of the spring equation via the formula Ω = 1.6783469f / smoothingHalfLife.

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