kaustubh-nair / Hierarchical-Animation-Framework-in-OpenGL

Animation framework in OpenGL, which uses a Tree-based datastructure for storing Scene Nodes.

Hierarchical Animation Framework

This project provides an abstract layer to make animations simpler in OpenGL.

It currently supports:

• Parent/child relationships between nodes.
• Timer and event based updates for animation.
• Movable camera, lights and mesh nodes.
• Collision detection.
• Target constrained relationships between nodes.
• Configurable textures.

Dependencies

Make sure you include stb_image.h in /include. If you choose to include it somewhere else, modify the Makefile appropriately.

Overview

Here's a brief overview of the various classes and methods available for animating a scene. For a more complete example, look at source/main.cpp in the example branch.

Scene Nodes

CameraNode, LightNode, and MeshNode are the three available classes for creating Scene nodes. Custom overrides can be made to these classes by inheriting them. Specifically, the MeshNode class must be inherited and the update() method should be implemented for making the objects move. Currently, only .ply files can be loaded as meshes.

Node Relationships

Since the nodes are stored in a tree, any transformations applied to a parent node will be applied to all of its child nodes. Parent/child dependencies can be defined in the MeshNode constructors using their the object ids. Target relationships can be defined between nodes when an object's state/action depends on another object, but the nodes do not have a parent/child relationship. These can be defined by creating a TargetNode object and storing the respective target id in the MeshNode object.

Defining movement

There are three transformation matrices for defining movement in MeshNode - translationMat, rotationMat, scalingMat. All these matrices are passed to the nodes' children. If a transformation is supposed to by applied only to the current node and not it's children, then new matrices need to be used and composed during MeshNode.render(). As an example, look at selfScalingMat. All these matrices are defined in the constructors and modified the inherited MeshNode's update() method for actions/movement.

There is a global timer, and on every tick the transformation matrices are updated and scene is rendered. Events can be defined in include/definitions.h and used in the update() methods.

Collision detection

Collision detection can be implemented with the help of the bounding sphere and minimum seperation defined in MeshNode.

Misc.

• Group nodes exist for performing group operations on a specific node type.
• Multiple windows can be created for multiple views.
• Input callbacks are defined in View.listenToCallbacks() and passed to Controller.reactToCallback()