Note that the tongue of the raptor is drawn between the two jaw attachments. The mesh is scaled down and tinted to be slightly darker than the front of the jaw.

To give the jaw a 3D look, the jaw bone contains another bone called jaw-inside which contains a copy of the raptor-jaw mesh. This ensures that the jaw does not look disconnected from the rest of the head when it is rotated. Like the thighs of the raptor, the vertices around the pivot of the jaw have been weighted to the head bone. The jaw is represented by the raptor-jaw mesh attachment.

As a general rule, if a mesh needs to be bent in either direction then the mesh image should be straight when the bones are bound. The raptor-body image has the tail in a straight line to improve its deformation when bending it in either direction. Its vertices are weighted to the bones making up parts of the upper body, like the torso and the tail. The upper body of the raptor is composed of a single mesh attachment raptor-body. The vertices of the raptor-front-leg mesh attachment are weighted to the the leg bones, deforming smoothly when the bones are transformed. The front-leg1 bone is the only bone in this leg bone hierarchy that has a slot containing an attachment. We disabled Inherit Rotation for front-foot2 to ensure the foot doesn’t go through the ground when rotating its parent bone. This allows us to easily bend the leg or bend the heel.Īt the tip of the leg, we have the front-foot1 bone and its child bone front-foot2. Moving the target bones will cause the IK constrained bones to follow. These two IK constraints target bones outside the raptor body bone hierarchy: front-foot-goal and front-leg-goal. The order in which constraints are applied is defined by their order in the Constraint node of the tree view. We first apply the front-leg-ik constraint and then the front-foot-ik constraint. Note that the order in which those two IK constraints are applied to the bones is important. The two-bone IK constraint front-leg-ik controls the front-leg1 and front-leg2 bones, while the two-bone IK constraint front-foot-ik drives the front-leg3 and front-foot1 bones. The leg is driven by two IK constraints: front-leg-ik and front-foot-ik. For brevity, we will only discuss the front leg in detail. The raptor's front and back legs are setup in the same way. This helps to keep the vertices at the edge of the meshes in the correct place when the hip bone is rotated. The vertices of the thigh mesh attachments are weighted to the the hip bone, in addition to the bones making up the raptor's legs. The hip bone serves as a control bone with which we can adjust the entire raptor body. The hip bone is the root of the raptor's body bone hierarchy to which the legs, tail, and torso are attached. It also employs techniques to give the skeleton a more 3D look.

The Raptor project demonstrates the use of weighted meshes and IK.

Esoteric software spine hips examples