QAngle

QAngle 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

QAngle angMyAngle = QAngle(-45,10,0);

• You could also assign to the X, Y and Z member variables separately.
• The prefix ang (or sometimes just a) identifies the variable as an angle.

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: The difference between intrinsic and extrinsic rotations, is that with the former, each rotation shifts the axes along with it The difference between proper Euler angles and Tait-Bryan angles, is that the former rotates twice around one axis and once around another (alternatingly), while the latter rotates once around all three axes The right-hand rule states that if the thumb of one's right hand is pointing along the positive direction of an axis, their other fingers will curl in the positive direction of rotation 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 you might see the terms Tilt (up/down), Pan (left/right) and Roll (slant left/right) when talking about 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)

Presence

• SP 2013 (blob master)
• MP 2013 (blob master)

See also

• Wikipedia:Yaw, pitch, and roll
• getpos
• Vector and Coordinates
• AngleVectors() / VectorAngles()