Hello Coders, I'm trying to create a space flight combat game with the Source SDK. Currently, I am trying to achieve rotation around the player's local axes for airplane-like pitch, yaw and roll. Below is the code I'm using to try to implement full 3D rotation. I'm running into a problem where the player's view twists and hitches unsmoothly when the player looks straight up or straight down. I think this may be because of the inherent problem of aliasing/Gimbal-lock when using Euler angles. Any advise?
//######################################### //Take the Euler angles for the player's orientation (viewangles) and convert them to vectors. Vector vec_for, vec_rt, vec_up, vec_for_out, vec_rt_out, vec_up_out; AngleVectors(viewangles, &vec_for, &vec_rt, &vec_up); //Take the resulting vectors and the desired rotation amounts and convert them to Quaternions. Quaternion turn_q, look_q, roll_q; // NOTE: Assumes axis is a unit vector, non-unit vectors will bias the resulting rotation angle (but not the axis) VectorNormalize(vec_up); AxisAngleQuaternion(vec_up, turn_angle, turn_q); VectorNormalize(vec_rt); AxisAngleQuaternion(vec_rt, look_angle, look_q); VectorNormalize(vec_for); AxisAngleQuaternion(vec_for, roll_angle, roll_q); //Convert the quaternions to matrices. matrix3x4_t xform0, xform1, xform2; QuaternionMatrix(turn_q, xform0); QuaternionMatrix(look_q, xform1); QuaternionMatrix(roll_q, xform2); //Combine matrices. matrix3x4_t xformA, xformB; MatrixMultiply(xform0, xform1, xformA); MatrixMultiply(xformA, xform2, xformB); //Rotate the vectors with our combined rotation matrix. VectorRotate(vec_for, xformB, vec_for_out); VectorRotate(vec_rt, xformB, vec_rt_out); VectorRotate(vec_up, xformB, vec_up_out); //Determine the new viewangles based on our rotated vectors. VectorAngles(vec_for_out, vec_up_out, viewangles); //######################################### I put this code into in_joystick.cpp in the JoyStickMove( float frametime, CUserCmd *cmd ) function. Thanks!
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