b3dTFormVectorY

Transforms vector and returns Y component (convenience wrapper for b3dTFormVector + b3dTFormedY). Takes x/y/z (vector direction in src space), sourceEntity (source coordinate system, 0=world space), destEntity (destination coordinate system, 0=world space). Returns transformed Y component (Double). Calls b3dTFormVector(x, y, z, sourceEntity, destEntity) then returns g_lastTFormedResult.y. Convenience function combining transform and retrieval.

This function combines transform and Y retrieval. Equivalent code: b3dTFormVector(x, y, z, src, dest), result=b3dTFormedY(), combined into single call for convenience. Vector transformation: applies rotation only (no scale/translation), uses XMVector3TransformNormal, preserves vector length (no normalization). Y-axis convention: returned value in user space (+Y up), already negated from internal DirectX space (-Y up) by b3dTFormVector. Use cases: (1) Get entity up Y (b3dTFormVectorY(0,1,0, entity, 0) for world up Y), (2) Get entity forward Y (b3dTFormVectorY(0,0,1, entity, 0) for world forward Y, useful for pitch), (3) Height component extraction (get Y of transformed direction), (4) Velocity transforms (get transformed velocity Y component), (5) Simplified code (single call instead of two). Common patterns: upY=b3dTFormVectorY(0,1,0, entity, 0) for entity up Y, forwardY=b3dTFormVectorY(0,0,1, entity, 0) for entity forward Y (pitch direction). Typical usage: extract single component of transformed vector without needing separate retrieval call, cleaner code for common operations. Coordinate systems: sourceEntity=0 for world space, destEntity=0 for world space, else uses entity rotation. Performance: O(1) transform + read (same cost as b3dTFormVector, just combined with retrieval). Side effect: updates g_lastTFormedResult (can retrieve X/Z with b3dTFormedX/Z if needed). Related: b3dTFormVectorX/Z return X and Z components, b3dTFormVector performs transform without returning component, b3dTFormedY retrieves Y without transform.