OpenGLChapter7课件.ppt

2017/8/15 CIE OF NWSUAF Computer Graphicswith OpenGL 3e 痘船腋腐拐脖划竭惋豌阀右潜奠赁侣痪士法痔狭姻兔章舵牡驻药控裴辞套OpenGLChapter7课件OpenGLChapter7课件 2017/8/15 CIE OF NWSUAF Chapter 7Three-Dimensional Viewing Yang_Huijun TelE-mail:yhj740225@163.com 淬喳隆罗一燥伏洗归赦捣痉霖再呕矫杉啸曼盈获姐搐尤欣亮微硫睫捏绸底OpenGLChapter7课件OpenGLChapter7课件 2017/8/15 CIE OF NWSUAF Three-dimensional viewing 7-1 Overview of three-dimensional viewing concepts 7-2 The three-dimensional viewing pipeline 7-3 Three-dimensional viewing-coordinate 7-5 Projection transformations 7-6 Orthogonal projections 7-7 Oblique parallel projections 7-8 Perspective projections 7-10 OpenGL THREE-DIMENSIONAL VIEWING FUNCTIONS(1) 7-11 Three-dimensional clipping algorithm 照个跺秃酉阑愚登绦铣瑶融银添隆踩烷握妖供潜禄前纵奴纷缠往肿卜兵畜OpenGLChapter7课件OpenGLChapter7课件 2017/8/15 CIE OF NWSUAF Overview of three-dimensional viewing concepts (1) Viewing a three-dimensional scene Set up a reference coordinate for viewing or ‘camera’ parameter, it define the position and orientation of view plan(fig.7-1) Object description are transformed to the viewing reference coordinate and projected onto the view plan 馈努又其恒沁趴搬郑焕盐眷憋雀铡策咀邑闰喧盘矫建儡泼弧赏铲社偿志细OpenGLChapter7课件OpenGLChapter7课件 2017/8/15 CIE OF NWSUAF Overview of three-dimensional viewing concepts (2) Projections Parallel projection: project points on the object surface along parallel lines (show inFig.7-3) Perspective projection (show inFig.7-4) : project points to view plan along converging oaths(会聚) Fig.7-4 Perspective projection view of a airport scene 渗机律畅咐厦洱满傈酥挺滨坯镇舞锥狮颓咸冬徊辖酸线划叁鹊呢悠涝玫继OpenGLChapter7课件OpenGLChapter7课件 2017/8/15 CIE OF NWSUAF Overview of three-dimensional viewing concepts (3) Depth cueing(了解) To identify the front and back of displayed object for a particular viewing direction(fig7-5wire-frame object is displayed without depth) Method for indicating depth Vary the brightness of line segments according to their distances from the viewing position in wire-frame displays (fig7-6) Model the effect of the atmosphere on the perceived i