rswiki-book/317-Camera-shake.mediawiki

[[Category Packet]]
[[Category Packet 317]]
{{packet|name=Camera oscillate|description=Begin camera oscillation|opcode=35|type=Fixed|length=4|revision=317}}
== Camera oscillate ==

=== Description ===
Begins camera oscillation, which is implemented using a configurable sinusoidal oscillator to offset a specific degree of freedom.

=== Packet Structure ===

{| border=2
! Data type
! Description
|-
| [[Data Types#Standard data types|Byte]]
| Parameter (camera X, Z, Y, yaw, pitch)
|-
| [[Data Types#Standard data types|Byte]]
| Jitter - for randomization
|-
| [[Data Types#Standard data types|Byte]]
| Amplitude
|-
| [[Data Types#Standard data types|Byte]]
| Frequency (scaled by 100)
|-
|}

=== Other Information ===
The oscillate event enables the client to oscillate one of 5 of it's position parameters, i.e. corresponding to the camera's degrees of freedom; parameters 0, 1, and 2 refer to the location of the camera, while 3 and 4 deal with the camera's orientation. Together, these enable complex effects involving manipulation of the camera position to give rise to simulated earth-quakes and camera shock.
{| border=2
! Parameter
! Description
|-
| 0
| Camera location along world X axis (a horizontal axis, aligned with map grid X)
|-
| 1
| Camera location along world Z axis (vertical axis)
|-
| 2
| Camera location along world Y axis (a horizontal axis, aligned with map grid Y)
|-
| 3
| Camera orientation in world X plane w.r.t. world Z axis, i.e. yaw
|-
| 4
| Camera orientation in world Z plane w.r.t. world X axis, i.e. pitch
|-
|}
Note there is no built-in way to manipulate camera roll, as this is not one of the camera's degrees of freedom.

=== What it's doing ===
Every time the world is rendered, each camera parameter that is enabled for oscillation is offset by a value computed as follows:
{| border=2
! Calculation
! Formula
|-
| Delta
| (int) ((Math.random() * (double) (jitter * 2 + 1) - (double) jitter) + Math.sin((double) phase * ((double) frequency / 100D)) * (double) amplitude);
|-
|}
Each parameter's phase accumulator (phase) is incremented by 1 each logic update.

=== Parameter ===
The offset itself is detailed as follows for each parameter:
{| border=2
! Parameter
! Action
|-
| 0
| camera_x += delta
|-
| 1
| camera_z += delta
|-
| 2
| camera_y += delta
|-
| 3
| camera_yaw = camera_yaw + delta & 0x7ff;
|-
| 4
| camera_pitch += delta
|-
|}
Note that the camera's yaw is corrected modulo 0x7ff, or 2048, which is equivalent to 2{{{pi}}} radians in Jagex's binary angle system.
This is not done to the camera pitch, which is instead clamped (see below).

=== Note ===
For oscillating the camera pitch, clamping is done to ensure the angle not out of bounds:
{| border=2
|-
|if (camera_pitch < 128) then camera_pitch = 128
|-
|if (camera_pitch > 383) then camera_pitch = 383
|-
|}
This is do to Jagex restricting the possible range of orientations the camera may take.