科学计算科学计算 (46).pdf

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1、Line ObjectSurface ObjectLightingReflectance Characteristics of Graphics Objects8.2 Line 8.2 Line and and SurfaceSurface(1)Create line objectSyntaxhandle=line(x,y,z,property1,value1,property2,value2,)Arguments x,y and z are vectors or matrices of the same type,which store the data of points.1.Line O

2、bject1.Line Object1.Line Object1.Line Object(2)Line PropertiesLineStyle:Specify line style.The default value is-Color:Specify line color.The default value of 0 0 0 corresponds to black.LineWidth:Specify line width.The default value is 0.5 points.Marker:Specify marker symbol,can take the same value a

3、s that of the plotfunction.MarkerSize:Specify marker size,default value is 6 points.XData,YData,Zdata:Set x,y,z values,which are vectors.t=-0.1:0.1:2*pi;x=cos(t);y=sin(t);line(x,y,Color,b)line(x+1.2,y-1,Color,y)line(x+2.4,y,Color,k)line(x+3.6,y-1,Color,g)line(x+4.8,y,Color,r)ha=gca;for n=1:size(ha.C

4、hildren)ha.Children(n).LineWidth=5;endha.XLim=-2,7;ha.YLim=-3,2;axis equalExample 1:Plot five circular lines using line objects.(1)Create surface objectUse the surface function to create a surface object.Syntax handle=surface(x,y,z,c,property1,value1,property2,value2,)Argument x,y,z are matrices of

5、the same size.Argument c specifies surface color according to the different heights.The surf function refresh the axes,delete the original plots before plotting.The surface function adds new plot to the current graph without deleting original plots.The surface function view the graph above the surfa

6、ce by default.Namely,the azimuth is 0 and elevation is 90.2.Surface 2.Surface ObjectObject(2)Surface Properties FaceColor:Define face color,which can be specified as:flat:Each face is filled with a single color.Its default.interp:Each face is filled with gradients.none:Do not draw the faces.texturem

7、ap:Each face is conformed with color specifyd in Cdata property.An RGB triplets or a color nameEdgeColor:Specify edge line color.2.Surface 2.Surface ObjectObjectr=linspace(0,2*pi,60);u,v=meshgrid(r);x=(8+3*cos(v).*cos(u);y=(8+3*cos(v).*sin(u);z=3*sin(v);axes(view,-37.5,30)hs=surface(x,y,z);axis equa

8、l;=8+3 cos=8+3 sin=3，u0,2，v0,2Example 2:Plot 3-D torus using surface objects.The equation of torus is:hs.EdgeColor=none;hs.FaceColor=interp;(1)Create Light ObjectSyntaxhandle=light(property1,value1,property2,value2,.)Light properties control the appearance and behavior of Light objects.(2)Light Prop

9、ertiesColor:Color of light.Style:Type of light source,specified as one of values:infinite(default)or local,which respectively means the light is placed infinitely far away or local.Position:Direction(for infinite light sources)or the location(for local light sources).3.Lighting3.Lighting(3)Lighting

10、MethodSpecify lighting algorithm.Syntaxlighting methodMethod can be specified as one of these values:flat(default):produces uniform lighting across each of the faces of the object.gouraud:calculates the vertex normals and interpolates linearly across the faces.Phong:interpolates at vertex normals an

11、d then calculates the reflection of each pixel.none:turns off lighting.3.Lighting3.Lightingr=linspace(0,2*pi,60);u,v=meshgrid(r);x=(8+3*cos(v).*cos(u);y=(8+3*cos(v).*sin(u);z=3*sin(v);axes(Position,0.05,0.675,1.0,0.3,View,-37.5,30);hs1=surface(x,y,z);axis equal;hs1.EdgeColor=none;hs1.FaceColor=inter

12、p;axes(Position,0.05,0.35,1.0,0.3,View,-37.5,30);hs2=surface(x,y,z);axis equal;hs2.EdgeColor=none;hs2.FaceColor=interp;light(Position,0,0,8)lighting flataxes(Position,0.05,0.025,1.0,0.3,View,-37.5,30);hs3=surface(x,y,z);axis equal;hs3.EdgeColor=none;hs3.FaceColor=interp;light(Position,0,0,8)Lighting

13、 phongExample 3:Plot torus under specified lighting.Observe the effects of different lightobjects on surface.SpecularStrength:Control the amount of specular reflection from the surface of anobject.Its value ranges from 0 to 1,default value is 0.9.DiffuseStrength:Control the amount of diffuse reflect

14、ion.Its value ranges from 0 to 1,default value is 0.6.AmbientStrength:Determine the intensity of the ambient light.Its value ranges from 0to 1,default value is 0.3.SpecularExponent:Specify the size of the specular highlight spot,which is greater thanor equal to 1.Most materials have exponents in the

15、 range 5 20,default value is 10.BackFaceLighting:Discriminate between the internal and external surfaces of an object.Its Values can be unlit,lit,and reverselit.4 4.Reflectance Characteristics of Graphics Objects.Reflectance Characteristics of Graphics Objects r=linspace(0,2*pi,60);u,v=meshgrid(r);x

16、=(8+3*cos(v).*cos(u);y=(8+3*cos(v).*sin(u);z=3*sin(v);axes(Position,0.05,0.675,1.0,0.3,View,-37.5,30);hs1=surface(x,y,z);axis equal;hs1.EdgeColor=none;hs1.FaceColor=interp;light(Position,0,0,8);lighting phonghs1.SpecularStrength=0.1;axes(Position,0.05,0.35,1.0,0.3,View,-37.5,30);hs2=surface(x,y,z);a

17、xis equal;hs2.EdgeColor=none;hs2.FaceColor=interp;light(Position,0,0,8);lighting phonghs2.SpecularStrength=0.5;axes(Position,0.05,0.025,1.0,0.3,View,-37.5,30);hs3=surface(x,y,z);axis equal;hs3.EdgeColor=none;hs3.FaceColor=interp;light(Position,0,0,8);lighting phong;hs3.SpecularStrength=1.0;Example 4:Plot torus with different strengths of specular reflection.Observe howreflectance characteristics affect the way graphics look.