第五章_OpenGL光照与材质(二)

1、第五章 光照与材质5.8 全局环境光每个光源可以有自己的环境光，但也可以有不来自于任何光源的环境光，指定环境光的方法是：利用参数GL_LIGHT_MODEL_AMBIENT来调用函数glLightModel*()。如：float model_ambient = 0.2 , 0.2 , 0.2 , 1.0 ; glLightModelfv(GL_LIGHT_MODEL_AMBIENT , model_ambient ) ;上述代码为场景中的物体提供了软弱的白色环境光，所以即使场景中没有任何光源，也可以看到场景中的物体。【综合示例EP5-5】场景中绘制一组静物模型，然后加入一个简单的光照，先使用光

2、源自己的环境光，再统一使用全局环境光。代码如下：#include stdafx.hint nAngleY=0;/ 沿Y轴旋转的角度int nAngleX=0;/ 沿X轴旋转的角度int nAngleZ=0;/ 沿Z轴旋转的角度void CALLBACK ClockwiseRotateByX()nAngleX-;void CALLBACK CounterClockwiseRotateByX()nAngleX+;void CALLBACK ClockwiseRotateByZ()nAngleZ-;void CALLBACK CounterClockwiseRotateByZ()nAngleZ+;v

3、oid CALLBACK ClockwiseRotateByY()nAngleY-;void CALLBACK CounterClockwiseRotateByY()nAngleY+;void myinit (void) /* 将背景清为白色 */glClearColor (0.0, 0.0,0.0, 1.0);glShadeModel (GL_SMOOTH); GLfloat ambient = 0.5, 0.0, 0.0, 1.0 ; GLfloat specular = 1.0, 1.0, 0.0, 1.0 ; GLfloat diffuse = 0.5, 0.5, 0.5, 1.0 ;

4、 GLfloat light_position = 1.0, 1.0, 1.0, 0.0 ; GLfloat model_ambient = 0.3, 0.0, 0.3, 1.0 ; GLfloat mat_specular = 1.0, 1.0, 1.0, 1.0 ; GLfloat mat_shininess = 128.0 ; glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess); glLightfv(GL_LIGHT1, GL_POSI

5、TION, light_position); /glLightfv (GL_LIGHT1, GL_AMBIENT, ambient); glLightfv (GL_LIGHT1, GL_SPECULAR, specular); glLightfv (GL_LIGHT1, GL_DIFFUSE, diffuse); / 指定全局环境光 glLightModelfv(GL_LIGHT_MODEL_AMBIENT,model_ambient); glEnable(GL_LIGHTING); glEnable(GL_LIGHT1); glDepthFunc(GL_LEQUAL); glEnable(G

6、L_DEPTH_TEST);glEnable(GL_AUTO_NORMAL); glEnable(GL_NORMALIZE); void CALLBACK reshape(GLsizei w, GLsizei h) if (!h) return; glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); if (w = h) glOrtho (-500.0, 500.0, -500.0*(GLfloat)h/(GLfloat)w, 500.0*(GLfloat)h/(GLfloat)w, -500, 500);

7、 else glOrtho (-500.0*(GLfloat)w/(GLfloat)h, 500.0*(GLfloat)w/(GLfloat)h, -500.0, 500.0, -500, 500); glMatrixMode(GL_MODELVIEW);void CALLBACK display(void)glLoadIdentity(); glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);/清除背景glRotated(nAngleX,1,0,0);glRotated(nAngleY,0,1,0);glRotated(nAngleZ,0,0,

8、1); glLineStipple(1, 0x3F07); / 指定点划格式 glEnable(GL_LINE_STIPPLE); / 进入点划模式glBegin(GL_LINES);/ X轴：红 glColor3f (1.0, 0, 0); glVertex3d(-490,0,0);glVertex3d(490,0,0);/ Y轴：绿 glColor3f (0.0, 1.0, 0); glVertex3d(0,-490,0);glVertex3d(0,490,0);/ Z轴：蓝 glColor3f (0.0, 0.0, 1); glVertex3d(0,0,-490);glVertex3d(

9、0,0,490);glEnd(); glDisable(GL_LINE_STIPPLE);/离开点划模式 glColor3f (1.0, 0.0, 0); glPushMatrix();/ 车体glTranslatef(0,210,0);auxSolidBox(600, 20, 400);glPopMatrix();glPushMatrix();/ 左前腿glTranslatef(-260,100,180);auxSolidBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 左后腿glTranslatef(-260,100,-180);auxSoli

10、dBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 右前腿glTranslatef(260,100,180);auxSolidBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 右后腿glTranslatef(260,100,-180);auxSolidBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 球glTranslatef(-200,260,0);auxSolidSphere(40);glPopMatrix();glPushMatrix();/ 八面体g

11、lTranslatef(-200,260,160);auxSolidOctahedron(40);glPopMatrix();glPushMatrix();/ 圆锥体glTranslatef(-60,220,120);glRotatef(-90,1,0,0);auxSolidCone(60, 100);glPopMatrix(); glPushMatrix();/glTranslatef(60,270,0);glRotatef(40,0,1,0); auxSolidTeapot(70);glPopMatrix();glPushMatrix();/glTranslatef(240,360,0);

12、 auxSolidCylinder(40,140);glPopMatrix();auxSwapBuffers(); int _tmain(int argc, _TCHAR* argv) auxInitDisplayMode (AUX_DOUBLE | AUX_RGBA); auxInitPosition (0, 0, 1000, 700); auxInitWindow (全局环境光); myinit ();auxKeyFunc (AUX_LEFT, ClockwiseRotateByY); auxKeyFunc (AUX_RIGHT, CounterClockwiseRotateByY); a

13、uxKeyFunc (AUX_UP, ClockwiseRotateByX); auxKeyFunc (AUX_DOWN, CounterClockwiseRotateByX); auxKeyFunc (AUX_D, ClockwiseRotateByZ); auxKeyFunc (AUX_d, ClockwiseRotateByZ); auxKeyFunc (AUX_U, CounterClockwiseRotateByZ); auxKeyFunc (AUX_u, CounterClockwiseRotateByZ);auxReshapeFunc(reshape);/回调函数 auxMain

14、Loop(display); return 0;5.9 近视点和无穷远视点在无穷远点的情况下，场景中所有顶点到视点的方向都相同。采用近视点时（local viewpoint），结果的真实感会更强，但需计算每个顶点的方向，因此总体性能将下降。默认情况下，认为视点位于无穷远处，位置将影响镜面反射区计算，也就是说，顶点的镜面反射亮度取决于该顶点的法线、顶点相对于光源的方向和顶点相对于视点的方向。指定方法是：glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER , GL_TRUE) ;上述代码把视点放在坐标系的（ 0 ，0 ，0 ）处，若把视点放到无穷远处，则执行如下代码

15、glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER , GL_FALSE) ;上述代码可在EP5-5中实现。【综合示例EP5-6】场景中绘制一组静物模型，使用透视投影实现。把实验五中的投影方式，由平行投影改为透视投影。转动场景时，物体显示会出现不正常。其中一个关键是要加入面剔除功能，第二个关键是对于茶壶而言，其面的定义是按顺时针的，这与一般物体的定义不同。下面的关键代码已用粗体标出。#include stdafx.hint nAngleY=0;/ 沿Y轴旋转的角度int nAngleX=0;/ 沿X轴旋转的角度int nAngleZ=0;/ 沿Z轴旋转的角度vo

16、id CALLBACK ClockwiseRotateByX()nAngleX-;void CALLBACK CounterClockwiseRotateByX()nAngleX+;void CALLBACK ClockwiseRotateByZ()nAngleZ-;void CALLBACK CounterClockwiseRotateByZ()nAngleZ+;void CALLBACK ClockwiseRotateByY()nAngleY-;void CALLBACK CounterClockwiseRotateByY()nAngleY+;void myinit (void) /* 将

17、背景清为白色 */glClearColor (0.0, 0.0,0.0, 1.0);glClearDepth(1.0f);/ 深度范围在【，】之间glShadeModel (GL_SMOOTH);/ 光源属性值 GLfloat ambient = 0.5, 0.0, 0.0, 1.0 ; GLfloat specular = 1.0, 1.0, 0.0, 1.0 ; GLfloat diffuse = 0.5, 0.5, 0.5, 1.0 ; GLfloat light_position = 1.0, 1.0, 1.0, 0.0 ; / 材质属性值 GLfloat mat_specular =

18、 1.0, 1.0, 1.0, 1.0 ; GLfloat mat_shininess = 128.0 ; / 设置材质 glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT, GL_SHININESS, mat_shininess); / 设置光源 glLightfv(GL_LIGHT1, GL_POSITION, light_position); glLightfv (GL_LIGHT1, GL_AMBIENT, ambient); glLightfv (GL_LIGHT1, GL_SPECULAR

19、, specular); glLightfv (GL_LIGHT1, GL_DIFFUSE, diffuse); glEnable(GL_LIGHTING); glEnable(GL_LIGHT1); / 启动深度测试 glEnable(GL_DEPTH_TEST);glDepthFunc(GL_LEQUAL); / 启动自动法线glEnable(GL_AUTO_NORMAL); glEnable(GL_NORMALIZE); / 启动面剔除功能glEnable(GL_CULL_FACE); / 不渲染一些面的功能启动glFrontFace(GL_CCW);/ 指定正面的方向glCullFac

20、e(GL_BACK); / 不渲染背面 void CALLBACK reshape(GLsizei w, GLsizei h) if (!h) return; glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity();gluPerspective(60.0,w/h,1.0f,2000.0f); glMatrixMode(GL_MODELVIEW); glLoadIdentity();void CALLBACK display(void)glLoadIdentity(); glClear (GL_COLOR_BUF

21、FER_BIT|GL_DEPTH_BUFFER_BIT);/清除背景glTranslatef(0,0,-1200);glRotated(nAngleX,1,0,0);glRotated(nAngleY,0,1,0);glRotated(nAngleZ,0,0,1); glLineStipple(1, 0x3F07); / 指定点划格式 glEnable(GL_LINE_STIPPLE); / 进入点划模式glBegin(GL_LINES);/ X轴：红 glColor3f (1.0, 0, 0); glVertex3d(-490,0,0);glVertex3d(490,0,0);/ Y轴：绿

22、glColor3f (0.0, 1.0, 0); glVertex3d(0,-490,0);glVertex3d(0,490,0);/ Z轴：蓝 glColor3f (0.0, 0.0, 1); glVertex3d(0,0,-490);glVertex3d(0,0,490);glEnd(); glDisable(GL_LINE_STIPPLE);/离开点划模式glFrontFace(GL_CCW); glColor3f (1.0, 0.0, 0); glPushMatrix();/ 车体glTranslatef(0,210,0);auxSolidBox(600, 20, 400);glPop

23、Matrix();glPushMatrix();/ 左前腿glTranslatef(-260,100,180);auxSolidBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 左后腿glTranslatef(-260,100,-180);auxSolidBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 右前腿glTranslatef(260,100,180);auxSolidBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 右后腿glTranslatef(

24、260,100,-180);auxSolidBox(25, 200, 25);glPopMatrix();glPushMatrix();/ 球glTranslatef(-200,360,0);auxSolidSphere(40);glPopMatrix();glPushMatrix();/ 八面体glTranslatef(-200,360,160);auxSolidOctahedron(40);glPopMatrix();glPushMatrix();/ 圆锥体glTranslatef(-60,300,120);glRotatef(-90,1,0,0);auxSolidCone(60, 100

25、);glPopMatrix();glFrontFace(GL_CW);glPushMatrix();/glTranslatef(60,300,0);glRotatef(40,0,1,0); auxSolidTeapot(70);glPopMatrix();glFrontFace(GL_CCW);glPushMatrix();/glTranslatef(240,362,0); auxSolidCylinder(40,140);glPopMatrix();auxSwapBuffers(); int _tmain(int argc, _TCHAR* argv) auxInitDisplayMode

26、(AUX_DOUBLE | AUX_RGBA|AUX_DEPTH); auxInitPosition (0, 0, 1000, 700); auxInitWindow (透视投影下的光照); myinit ();auxKeyFunc (AUX_LEFT, ClockwiseRotateByY); auxKeyFunc (AUX_RIGHT, CounterClockwiseRotateByY); auxKeyFunc (AUX_UP, ClockwiseRotateByX); auxKeyFunc (AUX_DOWN, CounterClockwiseRotateByX); auxKeyFun

27、c (AUX_D, ClockwiseRotateByZ); auxKeyFunc (AUX_d, ClockwiseRotateByZ); auxKeyFunc (AUX_U, CounterClockwiseRotateByZ); auxKeyFunc (AUX_u, CounterClockwiseRotateByZ);auxReshapeFunc(reshape);/回调函数 auxMainLoop(display); return 0;5.10材质OpenGL用材料对光的红、绿、蓝三原色的反射率来近似定义材料的颜色。象光源一样，材料颜色也分成环境、漫反射和镜面反射成分，它们决定了材料

28、对环境光、漫反射光和镜面反射光的反射程度（或者说成反射系数与前面的理论对应）。在进行光照计算时，材料对环境光的反射率与每个进入光源的环境光相乘，对漫反射光的反射率与每个进入光源的漫反射光相乘，对镜面光的反射率与每个进入光源的镜面反射光相乘。对环境光与漫反射光的反射程度决定了材料的颜色，对镜面反射光的反射率通常是白色或灰色。镜面反射高光最亮的地方将变成具有光源镜面光强度的颜色。例如一个光亮的红色塑料球，球的大部分表现为红色，光亮的高光将是白色的。5.10.1 材质RGB值和光源RGB值的关系对于光源，R、G、B值等于R、G、B对其最大强度的百分比。若光源颜色的R、G、B值都是1.0，则是最强的白

29、光；若值变为0.5，颜色仍为白色，但强度为原来的一半，于是表现为灰色；若RG1.0，B0.0，则光源为黄色。对于材质，R、G、B值为材质对光的R、G、B成分的反射率。比如，一种材质的R1.0、G0.5、B0.0，则材质反射全部的红色成分，一半的绿色成分，不反射蓝色成分。也就是说，若OpenGL的光源颜色为（LR、LG、LB），材质颜色为（MR、MG、MB），那么，在忽略所有其他反射效果的情况下，最终到达眼睛的光的颜色为（LR*MR、LG*MG、LB*MB）。 对于两束光，相应的值分别为（R1、G1、B1）和（R2、G2、B2），则OpenGL将各个颜色成分相加，得到（R1+R2、G1+G2、B

30、1+B2），若任一成分的和值大于1（超出了设备所能显示的亮度）则约简到1.0。5.10.2 材质定义材质的定义与光源的定义类似。其函数为：void glMaterialifv(GLenum face,GLenum pname,TYPE param);定义光照计算中用到的当前材质。face可以是GL_FRONT、GL_BACK、GL_FRONT_AND_BACK，它表明当前材质应该应用到物体的哪一个面上；pname说明一个特定的材质；param是材质的具体数值，若函数为向量形式，则param是一组值的指针，反之为参数值本身。非向量形式仅用于设置GL_SHINESS。pname参数值具体内容见表5

31、-2。另外，参数GL_AMBIENT_AND_DIFFUSE表示可以用相同的RGB值设置环境光颜色和漫反射光颜色。GL_SHINESS值介于0,128之间，值越大，光斑越小，越集中。表5-2 材质参数介绍参数名缺省值说明GL_AMBIENT(0.2, 0.2, 0.2, 1.0)材料的环境光颜色GL_DIFFUSE(0.8, 0.8, 0.8, 1.0)材料的漫反射光颜色GL_AMBIENT_AND_DIFFUSE材料的环境光和漫反射光颜色GL_SPECULAR(0.0, 0.0, 0.0, 1.0)材料的镜面反射光颜色GL_SHINESS0.0镜面指数（光亮度）GL_EMISSION(0.0

32、, 0.0, 0.0, 1.0)材料的辐射光颜色GL_COLOR_INDEXES(0, 1, 1)材料的环境光、漫反射光和镜面光颜色【综合示例EP5-7】材质的综合示例。#include stdafx.hint nAngleY=0;/ 沿Y轴旋转的角度int nAngleX=0;/ 沿X轴旋转的角度int nAngleZ=0;/ 沿Z轴旋转的角度void CALLBACK ClockwiseRotateByX()nAngleX-;void CALLBACK CounterClockwiseRotateByX()nAngleX+;void CALLBACK ClockwiseRotateByZ(

33、)nAngleZ-;void CALLBACK CounterClockwiseRotateByZ()nAngleZ+;void CALLBACK ClockwiseRotateByY()nAngleY-;void CALLBACK CounterClockwiseRotateByY()nAngleY+;void myinit (void) /* 将背景清为白色 */glClearColor (0.0, 0.0,0.0, 1.0);glShadeModel (GL_SMOOTH); GLfloat ambient = 0.0, 0.0, 0.0, 1.0 ; GLfloat specular

34、= 1.0, 1.0, 0.0, 1.0 ; GLfloat diffuse = 1.0, 1.0, 1.0, 1.0 ; GLfloat light_position = 1.0, 1.0, 1.0, 0.0 ; GLfloat lmodel_ambient = 0.4, 0.4, 0.4, 1.0 ; GLfloat mat_specular = 1.0, 1.0, 1.0, 1.0 ; GLfloat mat_shininess = 128.0 ; glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRO

35、NT, GL_SHININESS, mat_shininess); glLightfv(GL_LIGHT1, GL_POSITION, light_position); glLightfv (GL_LIGHT1, GL_AMBIENT, ambient); glLightfv (GL_LIGHT1, GL_SPECULAR, specular); glLightfv (GL_LIGHT1, GL_DIFFUSE, diffuse); / 指定全局环境光 glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient); / 指定视点:GL_TRUE:

36、视点位于（，），GL_FALSE：视点在无穷远glLightModeli(GL_LIGHT_MODEL_LOCAL_VIEWER, GL_FALSE); glEnable(GL_LIGHTING); glEnable(GL_LIGHT1); glDepthFunc(GL_LEQUAL); glEnable(GL_DEPTH_TEST);glEnable(GL_AUTO_NORMAL); glEnable(GL_NORMALIZE); void CALLBACK reshape(GLsizei w, GLsizei h) if (!h) return; glViewport(0, 0, w, h

37、); glMatrixMode(GL_PROJECTION); glLoadIdentity(); if (w = h) glOrtho (-500.0, 500.0, -500.0*(GLfloat)h/(GLfloat)w, 500.0*(GLfloat)h/(GLfloat)w, -500, 500); else glOrtho (-500.0*(GLfloat)w/(GLfloat)h, 500.0*(GLfloat)w/(GLfloat)h, -500.0, 500.0, -500, 500); glMatrixMode(GL_MODELVIEW);void CALLBACK dis

38、play(void)GLfloat no_mat = 0.0, 0.0, 0.0, 1.0 ;GLfloat mat_ambient = 0.7, 0.7, 0.7, 1.0 ;GLfloat mat_ambient_color = 0.0, 0.8, 0.0, 1.0 ;GLfloat mat_diffuse = 0.1, 0.5, 0.8, 1.0 ;GLfloat mat_specular = 1.0, 1.0, 1.0, 1.0 ;GLfloat no_shininess = 0.0 ;GLfloat low_shininess = 5.0 ;GLfloat high_shinines

39、s = 100.0 ;GLfloat mat_emission = 0.3, 0.2, 0.2, 0.0;glLoadIdentity(); glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);/清除背景glRotated(nAngleX,1,0,0);glRotated(nAngleY,0,1,0);glRotated(nAngleZ,0,0,1); glLineStipple(1, 0x3F07); / 指定点划格式 glEnable(GL_LINE_STIPPLE); / 进入点划模式glBegin(GL_LINES);/ X轴：红 glC

40、olor3f (1.0, 0, 0); glVertex3d(-490,0,0);glVertex3d(490,0,0);/ Y轴：绿 glColor3f (0.0, 1.0, 0); glVertex3d(0,-490,0);glVertex3d(0,490,0);/ Z轴：蓝 glColor3f (0.0, 0.0, 1); glVertex3d(0,0,-490);glVertex3d(0,0,490);glEnd(); glDisable(GL_LINE_STIPPLE);/离开点划模式/* (1,1) draw sphere in first row, first column *

41、diffuse reflection only; no ambient or specular */ glPushMatrix(); glTranslatef (-375, 300, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse); glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat); glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess); glMaterialfv

42、(GL_FRONT, GL_EMISSION, no_mat); auxSolidSphere(100.0); glPopMatrix();/* (1,2) draw sphere in first row, second column * diffuse and specular reflection; low shininess; no ambient */ glPushMatrix(); glTranslatef (-125, 300.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat); glMaterialfv(GL_FRONT, G

43、L_DIFFUSE, mat_diffuse); glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT, GL_SHININESS, low_shininess); glMaterialfv(GL_FRONT, GL_EMISSION, no_mat); auxSolidSphere(100.0); glPopMatrix();/* (1,3) draw sphere in first row, third column * diffuse and specular reflection; high s

44、hininess; no ambient */ glPushMatrix(); glTranslatef (125, 300.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse); glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess); glMaterialfv(GL_FRONT, GL_EMIS

45、SION, no_mat); auxSolidSphere(100.0); glPopMatrix();/* (1,4) draw sphere in first row, fourth column * diffuse reflection; emission; no ambient or specular reflection */ glPushMatrix(); glTranslatef (375, 300.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, no_mat); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat

46、_diffuse); glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat); glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess); glMaterialfv(GL_FRONT, GL_EMISSION, mat_emission); auxSolidSphere(100.0); glPopMatrix();/* (2,1) draw sphere in second row, first column * ambient and diffuse reflection; no specular */ glPush

47、Matrix(); glTranslatef (-375, 0.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse); glMaterialfv(GL_FRONT, GL_SPECULAR, no_mat); glMaterialfv(GL_FRONT, GL_SHININESS, no_shininess); glMaterialfv(GL_FRONT, GL_EMISSION, no_mat); auxSolidSphere(100.

48、0); glPopMatrix();/* (2,2) draw sphere in second row, second column * ambient, diffuse and specular reflection; low shininess */ glPushMatrix(); glTranslatef (-125, 0.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse); glMaterialfv(GL_FRONT, GL_

49、SPECULAR, mat_specular); glMaterialfv(GL_FRONT, GL_SHININESS, low_shininess); glMaterialfv(GL_FRONT, GL_EMISSION, no_mat); auxSolidSphere(100.0); glPopMatrix();/* (2,3) draw sphere in second row, third column * ambient, diffuse and specular reflection; high shininess */ glPushMatrix(); glTranslatef

50、(125, 0.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient); glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse); glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular); glMaterialfv(GL_FRONT, GL_SHININESS, high_shininess); glMaterialfv(GL_FRONT, GL_EMISSION, no_mat); auxSolidSphere(100.0); glPopMatrix();/* (2,4) draw sphere in second row, fourth column * ambient and diffuse reflection; emission; no specular */ glPushMatrix(); glTranslatef (375, 0.0, 0.0); glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambi