Implementation Of Virtual Fish Model And Main Motion

The motion of any physical entity is governed at the lowest level by the laws of physics. The physics-based models for graphics not only ensure physical realism of the resulting motion but also allow subtle visually important motions to be animated automatically. Physics-based models consider the attribute of objects such as quality, moment of inertia and friction in the real world to cause the motion of objects automatically according to dynamics principle. It is critical to graphics study, and is also a difficult subject in the area of virtual reality how to realize the physical models for the locomotory entities effectively. This dissertation addresses on this field.(1)A physics-based and polygon models method is presented. This method emphasizes the motion synthesis approach simulate the appearance,locomotion and behavior of fish based on the main ideas about deformable virtual objects' physical-based modeling in virtual reality .It emphasizes the generality of computer animation,rather than its specific application in this thesis to fishes .The main components of our approach-modeling form and appearance,biomechanics, locomotion,perception,and behavior-carry over to the realistic modeling of other motion of objects, guarantee the motion of objects conform the laws of physics.(2)A deformable dynamic fish model is developed. Desigh a mass-spring-damper model consisting of 23 nodal point masses and many spring-damper units based on the bodies of most fishes are highly deformable structures.The units serve as uniaxial deformable elements whose arrangement maintains the structural stability of the body while allowing it to flex. Accoording to the weight and the muscle strength of fish body specify the mechanics of the mass-spring-damper model.The generalized Newtonian equations of motion governing the dynamic fish model take the form of a set of coupled second-order ordinary differential equations.To simulate the dynamics of the fish model,the differential equations of motion must be integrated over time.The system can become unstable in a variety of situations that may occur in the simulated dynamic world.Therefore,the stability of the numerical solution is an important consideration.(3) The swing mode of fin and pectoral fin is disscussed and the corresponding dynamic equation is constructed. The motor system of the virtual fish depend on the BCF (Body and/or Caudal Fin) propulsion model and pectoral fin locomotion to achieve,the equations of the virtual fish caudal fin and pectoral fin locomotion are set up by analyzing the correlative parameters and the mechanis. In order to realize the different motor skills of the virtual fish, an algorithm about motor skills is introduced. An object-oriented collision detection method is presented for the collision detection of the virtual fish, which reduces time complexity dramatically for collision detection.(4)An alrorithm of mesh simplification based on normals is made. The geometric display model of virtual fish is achieved by polygon model, this dissertationin presents a mesh simplification algorithm suitable for surfaces with lower curvature variation,which using edge collapse to delete edges in coplanar region and merge colliner edges according to the nomals ofthe end vertices ofedges.lt uses fewer polygons to represent the model of the virtual fish without Significant loss in the visual characteristics of the virtual fish,thus reducing greatly the complexity of the model and achieving higher rendering speed.(5)The animation system of virtual fish is achievedThe geometric display model is coupled to the dynamic model to complete the swimming,the motion skills ,avoiding and schooling of the virtual fish.