QAngle
QAngle ("Quake Angle") is a C++ class in Source that represents a three-dimensional extrinsic Tait-Bryan rotations following the right-hand rule, offset from the cardinal Z axis.
Each QAngle contains three vec t rotation values:
X
Roll +/- slant
Y
Pitch +down/-up
Z
Yaw +right/-left
id Tech 2, and by extension 
GoldSrc, 
Source, and 
Source 2, use YZX = Pitch, Yaw, Roll, therefore
(-45, 10, 0) means 45° up, 10° left and 0° roll.
Tip:The axes are sometimes called rX, rY and rZ to distinguish them from vector axes.
Note:Roll is clamped to +/-50 for player viewangles.Declaration
C++
QAngle angMyAngle = QAngle(-45,10,0);
- You could also assign to the X, Y and Z member variables separately.
- The prefix
ang(or sometimes justa) identifies the variable as an angle.
type QAngle = { pitch: number, yaw: number, roll: number };
Orientation
To get a feeling for how a QAngle(Qx, Qy, Qz) works, imagine a first-person perspective:
- Qx: Looking down or up corresponds to positive or negative [Y]
- Qy: Looking left or right corresponds to positive or negative [Z]
- Qz: Tilting your head so your right or left ear faces the ground corresponds to positive or negative [X]
To relate this back to vectors and coordinates: The values of [X], [Y], and [Z] correspond to a clockwise rotation (in degrees) around the absolute axes[confirm]
Positive angles are in "Clockwise rotation" around an axis, assuming the viewer is located at the origin looking out in the direction of said axis.
Naming Conventions
Different fields use different naming conventions to describe these angles. To clear up any conflicting terms, short explanations are included below. Source Engine seems to draw its lingo from Aerospace Engineering.
Aerospace Engineering
| When imagining a plane, pitch moves the nose up and down, yaw moves the nose left and right, and roll causes one wing to move up and the other wing to move down.
In Aerospace Engineering, this system is also referred to as Euler angles if — unlike QAngles — the axes rotate along. See "Mathematics" for clarification. |
Mathematics
Strictly speaking, QAngles would be defined as extrinsic Tait-Bryan rotations following the right-hand rule. The terms "Tait-Bryan angles" and "Euler angles" are sometimes used interchangeably however. Breaking down this name into digestible chunks:
Tip:Since many conflicting definitions are used in rotation, being explicit when it comes to naming can help avoid confusion |
Cameras
When talking about cameras the terms Tilt (up/down), Pan (left/right) and Roll (slant left/right) is used for camera (Gimbal) rotations. This is likely the reason why QAngle uses YZX coordinates.
Converting from Vector
As there is no specific datadesc keyfield for angles, one chosen in Hammer will arrive as a vector. Its ordinates will represent degrees of rotation and not coordinates so it must be fixed up before use:
QAngle angMyAngle = QAngle(vecFromHammer.x, vecFromHammer.y, vecFromHammer.z);
// Conversion back to a vector, if required
AngleVectors(angMyAngle, &vecFromHammer);
Note: AngleVectors() outputs normalized vectors (clamped to 1 unit)