Animation tools often rely on deformation techniques to manipulate the shape of characters or objects. These techniques allow animators to create complex movements and transformations for more realistic or exaggerated motion.
In this blog post, we will explore some commonly used deformation techniques in C++ that can be implemented in animation tools. We will discuss two popular techniques: skeletal animation and morph target animation.
Table of Contents
Skeletal Animation
Skeletal animation, also known as rigging, is a technique that involves attaching a hierarchical set of bones to a 3D model. Each bone represents a rigid transform, such as rotation and translation, which can be manipulated to deform the model.
Key components of skeletal animation:
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Bones: Bones define the structure of an articulated character. They are connected together in a hierarchical manner, forming a skeleton-like structure. Each bone has a local transform that represents its relative position and orientation with respect to its parent bone.
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Skinning: Skinning is the process of binding the vertices of a mesh to the bones of a skeleton. Each vertex is associated with one or more bones, and the deformation of these bones influences the final position of the vertices. There are various skinning algorithms available, including linear blend skinning (LBS) and dual quaternion skinning (DQS).
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Inverse Kinematics: Inverse kinematics is used to calculate the position and orientation of bones in a hierarchy based on the desired position and orientation of a specific end effector, such as a hand or a foot. This allows animators to easily manipulate the character’s limbs by moving its end effectors directly.
Implementing skeletal animation in C++ involves data structures to represent bones, skinning algorithms to deform the mesh, and algorithms to solve inverse kinematics problems.
Morph Target Animation
Morph target animation, also known as blend shape animation, is a technique that involves creating a set of predefined target shapes, called morph targets or blend shapes, and smoothly interpolating between them to achieve desired deformations.
Key components of morph target animation:
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Morph Targets: Morph targets are different shapes or poses of a 3D model. Each morph target represents a specific deformation, such as a smile or a frown. These targets are created as additional meshes with the same vertex count as the base mesh.
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Weighted Blending: Weighted blending, also known as vertex interpolation, is the process of smoothly transitioning between different morph targets based on their corresponding weights. The weights determine the influence of each morph target on the final shape of the mesh. Interpolation can be performed using techniques such as linear interpolation or spherical linear interpolation (SLERP).
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Control Parameters: Control parameters, such as sliders or keyframes, are used to change the weights of the morph targets. These parameters provide animators with the ability to control the intensity and timing of deformations.
Implementing morph target animation in C++ involves storing and managing the morph targets, calculating the blending weights based on control parameters, and updating the mesh vertices accordingly.
Conclusion
Deformation techniques play a crucial role in creating realistic and expressive animations. Skeletal animation and morph target animation are two popular techniques used in animation tools. By implementing these techniques in C++ using appropriate data structures, algorithms, and libraries, developers can empower animators with powerful tools to bring characters and objects to life in their animations.
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