Camera Position / Camera Angle / Camera Target Position

OpenGL OpenGL: Basic Coding
1

Ok I have to admit that my math class was like ages ago… but…

How can I calculate the camera target position:

I have XYZ: camera position

I have XYZ: angles in degree

how can I calculate the XYZ of the camera target position assuming that the distance is 1.0f?

Cheers,

2

First, compute side, up, forward vectors from Euler angles, then translate forward vector with your camera position;
targetPosition = cameraPosition + forward

Here is a code snippet to compute from angles to axis vectors(side, up, forward). Notice that I use yaw, pitch and roll rotation order (RyRxRz). But, a different order of rotations produces different axis vectors, so try out yourself to multiply rotation matrice in different orders. And “Vector3” is simply a struct type of 3D vector.

///////////////////////////////////////////////////////////////////////////////
// convert Euler angles(x,y,z) to axis(side, up, forward)
// The order of rotation is Yaw->Pitch->Roll (Ry*Rx*Rz)
// Rx: rotation about X-axis, pitch
// Ry: rotation about Y-axis, yaw(heading)
// Rz: rotation about Z-axis, roll
//      Ry         Rx          Rz
// |Cy  0 -Sy| |1   0  0| | Cz Sz 0|   |CyCz-SySxSz  CySz+SySxCz  -SyCx|  <- side
// | 0  1   0|*|0  Cx Sx|*|-Sz Cz 0| = |-CxSz        CxCz         Sx   |  <- up
// |Sy  0  Cy| |0 -Sx Cx| |  0  0 1|   |SyCz+CySxSz  SySz-CySxCz  CyCx |  <- forward
///////////////////////////////////////////////////////////////////////////////
void anglesToAxis(const Vector3& angles, Vector3& side, Vector3& up, Vector3& forward)
{
    const float DEG2RAD = 3.141593f / 180;
    float sx, sy, sz, cx, cy, cz, theta;

    // rotation angle about X-axis (pitch)
    theta = angles[0] * DEG2RAD;
    sx = sinf(theta);
    cx = cosf(theta);

    // rotation angle about Y-axis (yaw)
    theta = angles[1] * DEG2RAD;
    sy = sinf(theta);
    cy = cosf(theta);

    // rotation angle about Z-axis (roll)
    theta = angles[2] * DEG2RAD;
    sz = sinf(theta);
    cz = cosf(theta);

    // determine side vector
    side[0] = cy*cz - sy*sx*sz;
    side[1] = cy*sz + sy*sx*cz;
    side[2] = -sy*cx;

    // determine up vector
    up[0] = -cx*sz;
    up[1] = cx*cz;
    up[2] = sx;

    // determine forward vector
    forward[0] = sy*cz + cy*sx*sz;
    forward[1] = sy*sz - cy*sx*cz;
    forward[2] = cy*cx;
}