Hello, i'm coding an export script from a 3D modeler (Blender) to my own engine written in OpenGL. Every object in the modeler has its own position, rotation, scale. I've a little trouble converting those values because where OpenGL uses the Z axis for depth (more depth -> negative values, less depth -> positive values) Blender instead uses the Y one instead (more depth -> POSITIVE values, less depth -> NEGATIVE values). I've converted x,y,z positions passing them as x, z, -y to my engine. Scaling instead is passed as x, z, y My trouble is converting rotation values. In the engine i use quaternions for handling in an easier way the calculations. I use this math library http://trenki.gippsbiz.com/math3d/ I'd like to pass the Euler angles of the rotation instead of the 4 components of the quarternion that Blender can calculate itself because people can better understand the rotation reading the xml file "by eye". Having the 3 angles Blender rotate first the object on its X angle, after the Y and finally the Z. I've tried to pass the angles in the x, z, y order to my engine. The quaterion class can be set with yaw, pitch, rool angles. So first i've multipled my "zero" quaternion with a quaternion setted with only x (pitch) value. But when in Blender the object rotate in a sense, in OpenGL in the other one. If i add also the other values the result in unpredictable. I'd like to know if i've to recalculate the angles in some ways because the depth axis is reversed and different or what. Thanks :)