MD5 swizzle
Author
I just got a Doom 3 MD5 model to render correctly, but i want to have it in XYZ coordinates rather than XZY coordinates. I tried flipping just the vertex positions, but then (of course) the skeleton won't be flipped. Then i tried flipping the quaternion values directly when i read the joints, and i got some really strange result (the model "marine" looks like some scary hellish alien. It could actually have been a real model [grin]).
Is there a simple way to do this, like flipping some values, or do i have to re-calculate all quaternions in some "proper" way?
Author
I managed to figure it out by myself. The secret is to rotate both the quaternion part and the pos part by a 90 degree axis quaternion. Here's the source if anyone should need it:
/** Quternion functions from http://tfc.duke.free.fr/coding/md5-specs-en.html*/float posVec[3] = { pos_x, pos_y, pos_z };float orientQuat[4] = { orient_x, orient_y, orient_z, 0.0f };Quat_computeW(orientQuat);// create 90 degree rotation quatfloat angle = (-90.0f / 180.0f) * 3.1415f;float axis[3] = { 1.0f, 0.0f, 0.0f };float rotQuat[4] = { axis[0] * sin(angle/2), axis[1] * sin(angle/2), axis[2] * sin(angle/2), cos(angle/2) };// rotate model from z-up to y-upQuat_rotatePoint(rotQuat, posVec, m->skeleton[jointCounter].pos);Quat_multQuat(rotQuat, orientQuat, m->skeleton[jointCounter].quat_orient);void Quat_computeW( quat4_t q ){ float t = 1.0f - (q[0] * q[0]) - (q[1] * q[1]) - (q[2] * q[2]); if( t < 0.0f ) { q[3] = 0.0f; } else { q[3] = -sqrt( t ); }}void Quat_multQuat( const quat4_t qa, const quat4_t qb, quat4_t out ){ out[3] = (qa[3] * qb[3]) - (qa[0] * qb[0]) - (qa[1] * qb[1]) - (qa[2] * qb[2]); out[0] = (qa[3] * qb[0]) + (qa[0] * qb[3]) + (qa[1] * qb[2]) - (qa[2] * qb[1]); out[1] = (qa[3] * qb[1]) + (qa[1] * qb[3]) + (qa[2] * qb[0]) - (qa[0] * qb[2]); out[2] = (qa[3] * qb[2]) + (qa[2] * qb[3]) + (qa[0] * qb[1]) - (qa[1] * qb[0]);}void Quat_rotatePoint( const quat4_t q, const vec3_t in, vec3_t out ){ quat4_t tmp, inv, final; inv[0] = -q[0]; inv[1] = -q[1]; inv[2] = -q[2]; inv[3] = q[3]; Quat_normalize( inv ); Quat_multVec( q, in, tmp ); Quat_multQuat( tmp, inv, final ); out[0] = final[0]; out[1] = final[1]; out[2] = final[2];}This topic is closed to new replies.
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