A framework for dynamic deformation of uniform elastic two-layer 2D and 3D objects in OpenGL

Abstract

This paper describes the design and implementation of a C++-based framework for two-layer uniform facet elastic object for real-time simulation based on physics modeling methods. The two-layered elastic object consists of inner and outer elastic mass-spring surfaces and compressible internal pressure. The density of the inner layer can be set differently from the density of the outer layer; the motion of the inner layer can be opposite to the motion of the outer layer. These special features, which cannot be achieved by a single layered object, result in improved imitation of a soft body, such as tissue's liquid non-uniform deformation. The inertial behavior of the elastic object is well illustrated in environments with gravity and collisions with walls, ceiling, and floor. The collision detection is defined by elastic collision penalty method and the motion of the object is guided by the Ordinary Differential Equation computation. Users can interact with the modeled objects, deform them, and observe the response to their action in real-time and we provide an extensible framework and its implementation for comparative studies of different physical-based modeling and integration algorithm implementations.

Designing an interactive OpenGL slide-based presentation of the softbody simulation system for teaching and learning of computer graphics techniques

“…Moreover, the object also contains 36 radius springs, 36 shear left springs, and 36 shear right springs between the inner and outer layers. Just like in two dimensions, the twolayer structure gives the 3D sphere more stability [12]. …”

“…This also closely correlates to the OpenGL state machine, that we use as a core library for our implementation. In our current simulation system, the application has been split into these three separated components [12].…”

“…If a 2D object with only one layer, or the object has no pressure force within, the spring's stiffness has to be a larger value than without, then the object will not collapse. However, as shown in Figure 2(b), if the spring stiffness is small enough, the object does not collapse, neither overlap with the layers because of the stability of the two-layer structure [12].…”

“…One can drag the object mass with a mouse to change its position. Effects of different simulation parameters are discussed [12].…”

Real-time modeling and physical-based animation of a jellyfish from softbody in OpenGL

“…We produce a similar type of animation but in real-time based on physics with the aim at a real-time tangible interaction or manipulation of the jellyfish in a game or an interactive installation with haptics and motion tracking. The design-and implementation-related work centers around deformable softbody objects simulation via physical based methods [2] applied to a certain type of softbody objects using the corresponding simulation framework [10] centered around OpenGL [9]. The CUGL [7] library that we use provides a set of convenient extensions to OpenGL.…”