Bidirectional Texture Sampling Of Feather Based On OpenGL

With the development of virtual reality technology,people have put forward further requirements for the degree of realism of three-dimensional virtual scenes.As the drawbacks of traditional virtual scene modeling technology,which has the problems of low modeling efficiency and poor authenticity,it brings new challenges to practical applications.In the existing research on third dimension modeling,the technology for modeling artificial objects has matured,but there is still a lack of mature and effective natural scenery modeling tools.For example,there is no feather modeling tools on the current popular modeling platforms.In this paper,as the basic work of three-dimensional feather realism modeling,in this article,we deal with the OpenGL-based bidirectional texture function(BTF)sampling of three-dimensional micro-structure model of feather.The main work is as follows:1.Establish a feather three-dimensional micro-structure model.Due to the rich surface structure of the feathers,the texture features of the feather surface are difficult to represent with traditional patch,texture,and lighting models.Therefore,it is necessary to perform texture sampling by establishing its micro-structure model.We use the popular 3D software Rhino to model and export the results to OBJ format files.2.Solve the two pivotal computational problems in the implementation of feather threedimensional micro-structure texture sampling:1)An in-depth study of the OpenGL processing pipeline explores the transformation from the user coordinate system to the screen coordinate system.By the feedback mechanism of the OpenGL pipeline,we solve the problem of calculating the coordinates of the screen image point for a given point in user coordinate system.2)The Bresenham algorithm is used to solve the problem of computing the image line segments in the frame buffer(FBO)for the two ends of the line segment in a given user coordinate system.3.Built a OpenGL application program based on glut library,in which we do several works including rendering three-dimensional microstructure of feather model into the frame buffer object,calculating the RGB color of the sampled image line segment in FBO,saving color information to the file,and finally the bidirectional texture function sampling of the feather is realized.