计算机图形图像绘制技术

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1、单击此处编辑母版标题样式,,单击此处编辑母版文本样式,,第二级,,第三级,,第四级,,第五级,,,*,计算机图形图像绘制技术,,第二讲,,,主要内容,,显示三维坐标的程序（1）,,几何对象的变换,,变换矩阵,,平移glTranslatef,,旋转glRotatef,,缩放glScalef,,三维实体,,显示三维坐标的程序（2）,,颜色,,点与线的属性,,面的显示,,隐藏面与深度缓冲,,多边形面的方向,,显示模式,,练习,,,,显示三维坐标的程序（1）,,,,变换矩阵,,在OpenGL中使用矩阵进行渲染三维场景所需要的数据计算,,为简化操作，OpenGL提供一个矩阵栈，每次用栈顶的矩阵对给定的物

2、体或场景进行渲染,,用glPushMatrix和glPopMatrix函数来将矩阵压栈和出栈，还可以用glScalef和glRotatef等函数对栈顶的矩阵进行缩放和旋转等修改,,Push / Pop Matrix,,void,glPushMatrix,(void);,,,Push Matrix,,Push / Pop Matrix,,Pop Matrix,void,glPopMatrix,(void);,,,,Example,,glPushMatrix();,,glTranslatef(...);,,glRotatef(...);,,glScalef(...);,,glutSolidCyli

3、nder(...);,,glPopMatrix();,,,平移glTranslatef,,void glTranslated (GLdouble x, GLdouble y, GLdouble z);,,void glTranslatef (GLfloat x, GLfloat y, GLfloat z);,,,演示,,,旋转glRotatef,,void glRotated (GLdouble angle, GLdouble x, GLdouble y, GLdouble z);,,void glRotatef (GLfloat angle, GLfloat x, GLfloat y, GL

4、float z);,,,演示,,缩放glScalef,,void glScaled (GLdouble x, GLdouble y, GLdouble z);,,void glScalef (GLfloat x, GLfloat y, GLfloat z);,,,演示,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,glRotatef (…)

5、;,,glPopMatrix();,,glPopMatrix();,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTransla

6、tef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,,Example,,glLoadIdentity();,,glPushMatrix();,,,glTranslatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMat

7、rix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,Translate,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,Translate,,,

8、Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPushMatrix();,,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,Translate,,Identity,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPu

9、shMatrix();,,glLoadIdentity();,,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,Translate,,Identity,,Translate,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,,glPopM

10、atrix();,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,Translate,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Ide

11、ntity,,Translate,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,Translate,,Rotate,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTran

12、slatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix();,,glPushMatrix();,,glRotatef (…);,,,glPopMatrix();,,glPopMatrix();,,Identity,,Translate,,,Example,,glLoadIdentity();,,glPushMatrix();,,glTranslatef (…);,,glPushMatrix();,,glLoadIdentity();,,glTranslate (…);,,glPopMatrix

13、();,,glPushMatrix();,,glRotatef (…);,,glPopMatrix();,,glPopMatrix();,,Identity,,,平移与旋转的次序很重要,,glLoadIdentity(),,,,glRotated(45, 0, 0, 1),,,,glTranslated(5, 0, 0),OpenGL commands successively define new “local” coordinate spaces in terms of the “current” or previous local space.,,三维实体对象,,Glaux.lib库,,

14、void auxWireSphere(GLdouble);,,void auxSolidSphere(GLdouble);,,void auxWireCube(GLdouble);,,void auxSolidCube(GLdouble);,,void auxWireBox(GLdouble, GLdouble, GLdouble);,,void auxSolidBox(GLdouble, GLdouble, GLdouble);,,void auxWireTorus(GLdouble, GLdouble);,,void auxSolidTorus(GLdouble, GLdouble);,,

15、void auxWireCylinder(GLdouble, GLdouble);,,void auxSolidCylinder(GLdouble, GLdouble);,,void auxWireIcosahedron(GLdouble);,,void auxSolidIcosahedron(GLdouble);,,void auxWireOctahedron(GLdouble);,,void auxSolidOctahedron(GLdouble);,,void auxWireTetrahedron(GLdouble);,,void auxSolidTetrahedron(GLdouble

16、);,,void auxWireDodecahedron(GLdouble);,,void auxSolidDodecahedron(GLdouble);,,void auxWireCone(GLdouble, GLdouble);,,void auxSolidCone(GLdouble, GLdouble);,,void auxWireTeapot(GLdouble);,,void auxSolidTeapot(GLdouble);,球,,立方体,,长方体,,圆环,,圆柱,,二十面体,,八面体,,四面体,,十二面体,,圆锥,,茶壶,,,Glut库,,void glutWireSphere(G

17、Ldouble radius, GLint slices, GLint stacks);,,void glutSolidSphere(GLdouble radius, GLint slices, GLint stacks);,,void glutWireCone(GLdouble base, GLdouble height, GLint slices, GLint stacks);,,void glutSolidCone(GLdouble base, GLdouble height, GLint slices, GLint stacks);,,void glutWireCube(GLdoubl

18、e size);,,void glutSolidCube(GLdouble size);,,void glutWireTorus(GLdouble innerRadius, GLdouble outerRadius, GLint sides, GLint rings);,,void glutSolidTorus(GLdouble innerRadius, GLdouble outerRadius, GLint sides, GLint rings);,,void glutWireDodecahedron(void);,,void glutSolidDodecahedron(void);,,vo

19、id glutWireTeapot(GLdouble size);,,void glutSolidTeapot(GLdouble size);,,void glutWireOctahedron(void);,,void glutSolidOctahedron(void);,,void glutWireTetrahedron(void);,,void glutSolidTetrahedron(void);,,void glutWireIcosahedron(void);,,void glutSolidIcosahedron(void);,,显示三维坐标的程序(2),,（演示）,,颜色,,glCo

20、lor3fv(face color),,render_face(),,glColor3fv(eye color),,render_eyes(),,glColor3fv(hair color),,render_hair(),,glColor3fv(teeth color),,render_teeth(),,Colors,颜色其有四个分量:,,,,R - 红 Red.,,G - 绿 Green.,,B - 蓝 Blue.,,A - 透明度 Transparent.,关于透明处理…,在后面讲,!,,glShadeModel(GL_FLAT);,,glBegin(GL_QUADS);,,glCo

21、lor3f (1.0,0.0,0.0);,,glVertex3f(0.0,0.0,0.0);,,glColor3f (0.0,1.0,0.0);,,glVertex3f(1.0,0.0,0.0);,,glColor3f (0.0,0.0,1.0);,,glVertex3f(1.0,1.0,0.0);,,glColor3f (1.0,1.0,0.0);,,glVertex3f(0.0,1.0,0.0);,,glEnd();,Shading Models,,,glShadeModel(GL_SMOOTH);,,glBegin(GL_QUADS);,,glColor3f (1.0,0.0,

22、0.0);,,glVertex3f(0.0,0.0,0.0);,,glColor3f (0.0,1.0,0.0);,,glVertex3f(1.0,0.0,0.0);,,glColor3f (0.0,0.0,1.0);,,glVertex3f(1.0,1.0,0.0);,,glColor3f (1.0,1.0,0.0);,,glVertex3f(0.0,1.0,0.0);,,glEnd();,Shading Models,,,演示,,,,点与线的属性,,,void,glPointSize(GLfloat,size);,,void,glLineWidth(GLfloat,width);,,

23、glLineStipple(1, 0x3F07);,glEnable(GL_LINE_STIPPLE);,,void,glLineStipple(GLint,factor,,Glushort,pattern);,,演示,,,,深度缓冲区,,当我们从某处看景物时，接近于视点的物体遮挡了离视点较远的物体。,,深度缓冲区为每个像素保存一个距离或深度值，以便让OpenGL通过简单方法做隐藏面计算。,,只有当新像素的深度值小于旧像素的深度值时，才允许像素的覆盖。,,,,,画家算法与深度排序,,,,画家算法的局限性,,解决办法：分割成两个,,演示,,,,多边形面的方向,,,,,back-face,norm

24、al pointing inside,,法线方向的指定方法一,,v,0,v,1,v,2,v,3,v,0,v,1,v,2,v,3,根据顶点顺序确定,,法线方向的指定方法二,,指定法线,,面的可见性,,void glCullFace (GLenum mode);,,GLenum取值：GL_FRONT、GL_BACK、GL_FRONT_AND_BACK,,多边形显示模式,,glPolygonMode(GLenum face, GLenum mode);,GL_FILL, GL_LINE, GL_POINT,GL_FRONT, GL_BACK, GL_FRONT_AND_BACK,GL_FILL,GL_LINE,GL_POINT,,演示,,,,练习,,1. 简单的城市模型,,,2 三维飞机模型,,,3,,,4 作三维成绩统计饼图或条形图,,第二次课和第三次课练习作为一次大作业;,,可任选题目;,,第一次大作业在第四次课,上课之前交.,,作业发email至:liuzhongtu@,,