OPENGL图形程序设计 OPENGL是一个三维图形和模型库,由于它在三维图形方面的杰出性能,目前许多高级语言都提供了与OPENGL的接口,如:VC、DELPHI、C++Builder等。使用OPENGL可以极大地减少用户开发图形、图像的难度,使用户制作高水准的商业广告、图形CAD、三维动画、图形仿真和影视采集。 一、OPENGL的功能 OPENGL原来是工作站上的一个图形软件库,由于它在商业、军事、医学、航天航空等领域的广泛应用,目前在低档电脑也可以开发出符合用户要求的图形。OPENGL不仅可以绘制基本图像,而且提供了大量处理图形图像的函数与过程。 1、图形变换 是图形显示与制作的基础,动画设计和动画显示都离不开图形的变换,图形变换在数学上是由矩形的乘法来实现的,变换一般包括平移、旋转和缩放。按图形的显示性质来分:视点变换、模型变换、投影变换、剪裁变换和视口变换等。 2、光照效果 不发光的物体的颜色是由物体反射外界光所形成的,这是光照。在三维图形中,如果光照使用不当,三维图形就会失去真实的立体感,OPENGL把光照分为:辐射光、环境光、散射光、反射光等。 3、纹理映射 通过纹理映射可以在三维表面添加显示现实世界中的纹理。如:一个矩形它不能表示真实世界中的物体,如果填上"本质"纹理,就逼真了。 4、图形特效 混合函数、反走样函数和雾函数,可以处理三维图形听之任之物体的透明和半透明、使用线段理加光滑以及提供雾化的效果。 5、图像特效 处理位图的基本函数:图像绘制、图像拷贝和存储、映射和转移、图像的缩放等。位图操作函数可以人绘图原的低层说明中文字符的形成过程。 二、创建OPENGL应用程序 1、一般原则 A 有uses中添加OPENGL支持单元:OpenGL; B 在窗体的OnCreate事件过程中初始化OPENGL; C 在窗口的OnPaing 事件过程中初始化OPENGL; D 在窗口的OnResize事件过程中初始化OPENGL; E 在窗口的OnDestroy 事件过程中初始化 OPENGL; 2、简单实例 A 创建一个工程FILE->New Application B 在OnCreate事件中添加代码: procedure TfrmMain.FormCreate(Sender: TObject); var pfd:TPixelFormatDescriptor; //设置描述表 PixelFormat:Integer; begin ControlStyle:=ControlStyle+[csOpaque]; FillChar(pfd,sizeof(pfd),0); with pfd do begin nSize:=sizeof(TPixelFormatDescriptor); nVersion:=1; dwFlags:=PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER; iPixelType:=PFD_TYPE_RGBA; cColorBits:=24; cDepthBits:=32; iLayerType:=PFD_MAIN_PLANE; end; PixelFormat:=ChoosePixelFormat(Canvas.Handle,@pfd); SetPixelFormat(Canvas.Handle,PixelFormat,@pfd); hrc:=wglCreateContext(Canvas.Handle); w:=ClientWidth; h:=ClientHeight; end; C 在OnDestroy事件中的代码 procedure TfrmMain.FormDestroy(Sender: TObject); begin wglDeleteContext(hrc); end; D 在OnPaint事件中的代码 procedure TfrmMain.FormPaint(Sender: TObject); begin wglMakeCurrent(Canvas.Handle,hrc); glClearColor(1,1,1,1); glColor3f(1,0,0); glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); MyDraw; glFlush; SwapBuffers(Canvas.Handle); end; E 在OnResize事件中的代码 procedure TfrmMain.FormResize(Sender: TObject); begin glMatrixMode(GL_PROJECTION); glLoadIdentity; glFrustum(-1.0,1.0,-1.0,1.0,3.0,7.0); glViewPort(0,0,ClientWidth,ClientHeight); MyDraw; end; F 在MyDraw函数中的代码(用户在窗口类中声明) procedure TfrmMain.MyDraw; begin glPushMatrix; Sphere:=gluNewQuadric; gluQuadricDrawStyle(Sphere,GLU_LINE); gluSphere(Sphere,0.5,25,25); glPopMatrix; SwapBuffers(Canvas.handle); gluDeleteQuadric(Sphere); end; 附本程序原码: unit MainFrm; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, OpenGL; type TfrmMain = class(TForm) procedure FormCreate(Sender: TObject); procedure FormDestroy(Sender: TObject); procedure FormPaint(Sender: TObject); procedure FormResize(Sender: TObject); private { Private declarations } hrc:HGLRC; w,h:glFloat; Sphere:GLUquadricObj; public { Public declarations } procedure MyDraw; end; var frmMain: TfrmMain; implementation {$R *.dfm} procedure TfrmMain.FormCreate(Sender: TObject); var pfd:TPixelFormatDescriptor; PixelFormat:Integer; begin ControlStyle:=ControlStyle+[csOpaque]; FillChar(pfd,sizeof(pfd),0); with pfd do begin nSize:=sizeof(TPixelFormatDescriptor); nVersion:=1; dwFlags:=PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER; iPixelType:=PFD_TYPE_RGBA; cColorBits:=24; cDepthBits:=32; iLayerType:=PFD_MAIN_PLANE; end; PixelFormat:=ChoosePixelFormat(Canvas.Handle,@pfd); SetPixelFormat(Canvas.Handle,PixelFormat,@pfd); hrc:=wglCreateContext(Canvas.Handle); w:=ClientWidth; h:=ClientHeight; end; procedure TfrmMain.FormDestroy(Sender: TObject); begin wglDeleteContext(hrc); end; procedure TfrmMain.FormPaint(Sender: TObject); begin wglMakeCurrent(Canvas.Handle,hrc); glClearColor(1,1,1,1); glColor3f(1,0,0); glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); MyDraw; glFlush; SwapBuffers(Canvas.Handle); end; procedure TfrmMain.MyDraw; begin glPushMatrix; Sphere:=gluNewQuadric; gluQuadricDrawStyle(Sphere,GLU_LINE); gluSphere(Sphere,0.5,25,25); glPopMatrix; SwapBuffers(Canvas.handle); gluDeleteQuadric(Sphere); end; procedure TfrmMain.FormResize(Sender: TObject); begin glMatrixMode(GL_PROJECTION); glLoadIdentity; glFrustum(-1.0,1.0,-1.0,1.0,3.0,7.0); glViewPort(0,0,ClientWidth,ClientHeight); MyDraw; end; end. 三、OPENGL变量和函数的约定 1、OPENGL的库约定 它共三个库:基本库、实用库、辅助库。在DELPHI中,基本库由OpenGL单元实现,在Windows环境中,一般不使用辅助库。 2、OPENGL常数约定 OPENGL常数均使用大写字母,以"GL"开头,词汇之间使用下划线分隔,如:GL_LINES,表示使用基本库绘制直线。 3、OPENGL函数的命名约定 A 第一部分以gl或wgl开头,如glColor3f中的gl。 B 第二部分是用英文表示的函数功能,单词的首字母大写出。 C 第三部分是数字,表示函数的参数。 D 第四部分是小写字母,表示函数的类型。 b 9位整数 s 16位整数 i 32位整数 f 32位浮点数 d 64位浮点数 ub 9位无符号整数 例:glVertex2f(37,40); {两个32位的浮点数作参数} glVertex3d(37,40,5); {三个64位的浮点数作参数} p[1..3]:array of glFloat; glVertes3fv(p); {3f表示三个浮点数,v表示调用一个数组作为顶点坐标输入} 四、OPENGL的初始化 1、PIXELFORMATDESCRIPTOR结构 主要描述像素点的性质,如像素的颜色模式和红、绿、蓝颜色构成方式等。 tagPIXELFORMATDESCRIPTOR = packed record nSize: Word; nVersion: Word; dwFlags: DWORD; iPixelType: Byte; cColorBits: Byte; cRedBits: Byte; cRedShift: Byte; cGreenBits: Byte; cGreenShift: Byte; cBlueBits: Byte; cBlueShift: Byte; cAlphaBits: Byte; cAlphaShift: Byte; cAccumBits: Byte; cAccumRedBits: Byte; cAccumGreenBits: Byte; cAccumBlueBits: Byte; cAccumAlphaBits: Byte; cDepthBits: Byte; cStencilBits: Byte; cAuxBuffers: Byte; iLayerType: Byte; bReserved: Byte; dwLayerMask: DWORD; dwVisibleMask: DWORD; dwDamageMask: DWORD; end; TPixelFormatDescriptor = tagPIXELFORMATDESCRIPTOR; dwFlags代表点格式的属性: PFD_DRAW_TO_WINDOW 图形绘在屏幕或设备表面 PFD_DRAW_TO_BITMAP 在内存中绘制位图 PFD_SUPPORT_GDI 支持GDI绘图 PFD_SUPPORT_OPENGL 支持OPENGL函数 PFD_DOUBLEBUFFER 使用双缓存 PFD_STEREO 立体缓存 PFD_NEED_PALLETTE 使用RGBA调色板 PFD_GENERIC_FORMAT 选择GDI支持的格式绘图 PFD_NEED_SYSTEM_PALETTE 使用OPENGL支持的硬件调色板 iPixelType设置像素颜色模式:PFD_TYPE_RGBA或PFD_TYPE_INDEX.。 cColorBits设置颜色的位,如是9表示有256种颜色表示点的颜色。 cRedBits、cGreenBits、cBlueBits 使用RGBA时,三原色所使用的位数。 cRedShitfs、cGreenShifts、cBlueShifts 使用RGBA时,三原色可以调节的位数。 cAlphaBits、cAlphaShifts 使用RGBA时,Alpha使用的位数与可调节的位数。 cAccumBits设置累积缓存区的位面总数。 cAccumRedBits、cAccumGreenBits、cAccumBlueBits设置累积缓存区的三原色位面总数。 cAccumAlphaBits设置累积缓存区的Alpha位面总数。 cDepthBits设置浓度缓存的深度。 cStencilBits设置Stencil缓存的深度。 cAuxBuffers指辅助缓存的大小。 iLayerType指定层的类型。 bReserved不使用,必须是零。 dwLayerMask指定覆盖层的屏蔽。 dwDamageMask设置在相同的框架缓存下是否共用同一种像素模式。 2、OPENGL的初始化步骤 A 使用Canvas.Handle获得窗口句柄。 B 创建一个TPixelFormatDescriptor变量定义像素格式。 C 使用ChoosePixelFormat函数选择像素格式。 D 使用SetPixelFormat函数使用像素格式生效。 E 使用wglCreateContext函数建立翻译描述表。 F 使用wglMakeCurrent函数把建立的翻译描述表作为当前翻译描述表。 3、资源释放 A 使用wglDeleteContext过程删除像素描述表。 B 使用ReleaseDC过程释放窗口内存。 在窗口的OnDestroy事件中: begin if hrc<>null then wglDeleteCurrent(hrc); if hdc<>null then ReleaseDC(Handle,hdc); end; 五、OPENGL基本图形的绘制 1、图形的颜色 注意底色的设置,颜色设置通常与像素描述变量有关,即与TPixelFormatDescriptor定义中的iPixelType成员有关。 iPixelType:=PFD_TYPE_COLORINDEX; 则只能使用glIndexd,glIndexf,glIndexi,glIndexs,glIndexv,glIndexfv,glIndexiv,glIndexsv过程设置图形颜色。 iPixelType:=PFD_TYPE_RGBA; 则只能使用 glColor3b,glColor3f,glColor4b,glColor4f,glColor4fv设置图形颜色。 A 图形底色:屏幕与窗口的颜色,即颜色缓冲区的颜色。改变图形底色首先应使用glClearColor过程设定底色,然后使用glClear过程以这种底色刷新窗口和屏幕。 procedure glClearColor(red:GLClampf,green:GLClampf,blue:GLClampf,alpha:GLClampf); procedure glClear(mask:GLBitField); red,green,blue,alpha是准备设置的底色,它们的取值是0到1。mask是刷新底色的方式。 例:将绘声绘色图窗口设置为绿色 glClearColor(0,1,0,1); glClear(GL_COLOR_BUFFER_BIT); mask的取值和意义: GL_COLOR_BUFFER_BIT 设置当前的颜色缓冲 GL_DEPTH_BUFFER_BIT 设置当前的深度缓冲 GL_ACCUM_BUFFER_BIT 设置当前的积累缓冲 GL_STENCIL_BUFFER_BIT 设置当前的STENCIL(模板)缓冲 绘图窗口设置为灰色 glClearColor(0.3,0.3,0.3,1); glClear(GL_COLOR_BUFFER_BIT); B 图形颜色 使用glClear3f与glClear4f可以设置图形的绘制颜色。若用三个参数,则分别指设置红、蓝、绿三色光。若用四个参数,则第四个表示RGBA值。 例设置当前的绘图颜色为蓝色: glColor3f(0,0,1); 设置绘图颜色为白色: glColor3f(1,1,1); 2、简单图形的绘制 在glBegin与glEnd过程之间绘制简单图形,如点、线、多边形等。 glBegin(mode:GLenum);{绘制过程}glEnd; mode的取值: GL_POINTS 画多个点 GL_LINES 画多条线,每两点绘制一条直线 GL_LINE_STRIP 绘制折线 GL_LINE_LOOP 绘制首尾相接的封闭多边形 GL_TRIANGLES 绘制三角形 GL_TRIANGLE_STRIP 绘制三边形,每三个点绘制绘制一个三边形 GL_TRIANGLE_FAN 绘制三角形 GL_QUADS 绘制四边形 GL_QUAD_STRIP 绘制四边条,每四点绘制一个四边条 GL_POLYGON 绘制多边形 例绘制三个点: begin glPushMatrix; glBegin(GL_POINT); glVertex2f(0.1,0.1); glVertex2f(0.5,0.5); glVertex2f(0.1,0.3); glEnd; SwapBuffers(Canvas.Handle); end; 如果将GL_POINT改为GL_LINES,则将画一条线.第三个点无效.在glVertex2f之前执行glColor3f(0,0,1)则将线条的颜色改为绿色. 如果将GL_LINES改为GL_LINE_STRIP则可以绘制两条直线. 使用glPointSize过程可以设置点的大小;使用glLineWidth过程可以设置线的宽度. 使用glLineStipple过程设置点划线的样板,使用glEnable(GL_LINE_STIPPLE)过程和对应参数使绘图能够绘制点划线.glDisable(GL_LINE_STIPPLE)过程和对应参数关闭点划线. procedure glLineStipple(factor:GLint,pattern:GLushort); 参数factor表示点划线样板Pattern的重复次数,factor取值1255,Pattern是二进制序列. glLineStipple(1,0,0x11C);{0x11C表示为10001110,0表示不画点,1表示画点} 例: begin glColor3f(1,0,0); glLineWidth(2); glLineStipple(1,$11C); glEnable(GL_LINE_STIPPLE); glBegin(GL_LINES); glVertex2f(-0.9,0.3); glVertex2f(0.9,0.3); glEnd; glDisable(GL_LINE_STIPPLE); glColor3f(1,0,1); glLineStipple(2,$11C); glEnable(GL_LINE_STIPPLE); glBegin(GL_LINES); glVertex2f(-0.9,0.1); glVertex2f(0.9,0.1); glEnd; glDisable(GL_LINE_STIPPLE); SwapBuffers(Canvas.Handle); end; 多边形绘制与点线相似,要改变参数为GL_POLYGON,GL_QUADS,GL_TRANGLES.在绘制时的注意事项: A 多边形的边与边只在顶点相交 B 多边形必须是凸多边形,如果是凹多边形,用户只有折成凸多边形,加快绘制速度. 例: glBegin(GL_POLYGON); glVertex2f(-0.9,0.3); glVertex2f(0.9,0.3); glVertex2f(0.9,-0.6); glVertex2f(0.5,-0.6); glVertex2f(-0.9,-0.2); glEnd; 多边形有正面与反面,与之相关的过程: glPolygonMode 控制多边形正,反面绘图模式 glFrontface 指定多边形的正面 glCullFace 显示多边形是设置消除面 glPolygonStripple 形成多边形填充的样式 3、简单二次曲面 圆柱,圆环和球都属于二次曲面. A 圆柱 gluCylinder(qobj:GLUquadricObj,baseRadius:GLdouble,topRadius:GLdouble,height:GLdouble, slices:GLint,stacks:GLint); qobj指定一个二次曲面,baseRadius为圆柱的底半径;topRadius为所绘制圆柱的上顶面半径;height为圆柱的高;slices为绕Z轴的分割线数;stacks为沿Z轴的分割线数. 如果baseRadius和topRadius不相等,则可以绘制锥台与圆锥. procedure TfrmMain.MyDraw; var qObj:GLUQuadricObj; begin glPushMatrix; glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); glColor3f(1,0,0); qObj:=gluNewQuadric; gluQuadricDrawStyle(qObj,GLU_LINE); gluCylinder(qObj,0.5,0.1,0.2,10,10); end; B 圆环 gluDisk(qobj:GLUquadricObj,innerRadius:GLdouble,outerRadius:GLdouble,slices:GLint, loops:GLint); procedure TfrmMain.MyDraw; var qObj:GLUQuadricObj; begin glPushMatrix; glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); glColor3f(1,0,0); qObj:=gluNewQuadric; gluQuadricDrawStyle(qObj,GLU_LINE); gluDisk(qObj,0.2,0.5,10,5); SwapBuffers(Canvas.Handle); end; C 半圆环 gluPartialDisk(qobj:GLUquadricObj,innerRadius:GLdouble,outerRadius:GLdouble,slices:GLint, loops:GLint,startAngle:GLdouble,sweepAngle:GLdouble); startAngle,sweepAngle是半圆环的起始角与终止角. procedure TfrmMain.MyDraw; var qObj:GLUQuadricObj; begin glPushMatrix; glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); glColor3f(1,0,0); qObj:=gluNewQuadric; gluQuadricDrawStyle(qObj,GLU_LINE); gluPartialDisk(qObj,0.2,0.5,10,5,90,190); SwapBuffers(Canvas.Handle); end; D 球体 function gluSphere(qObj:GLUquadricObj,radius:GLdouble,slices:GLint,stacks:GLint); procedure TfrmMain.MyDraw; var qObj:GLUQuadricObj; begin glPushMatrix; glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); glColor3f(1,0,0); qObj:=gluNewQuadric; gluQuadricDrawStyle(qObj,GLU_LINE); { silhouette[ silu(:)5et ]n.侧面影象, 轮廓} gluSphere(qObj,0.5,20,20); SwapBuffers(Canvas.Handle); end; E 关于二次曲面的过程 gluNewQuadric 创建一个新的二次曲面对象 gluDeleteQuadric 删除一个二次曲面对象 gluQuadricDrawStyle 指定要绘制的二次曲面类型 gluQuadricNormal 设置二次曲面的法矢量 gluQuadricOrientation 设置二次曲面是内旋还是外旋转 gluQuadricTexture 设置二次曲面是否使用纹理 F 绘制二次曲面的一般步骤 首先定义一个GLUquadricObj对象; 其次创建一个曲面对象gluNewQuadric; 再次设置二次曲面的特性(gluQuadricDrawStyle, gluQuadricTexture) 绘制二次曲面(gluCylinder,gluSphere,gluDisk, gluPartialDisk) 六、OPENGL中的变换 变换是动画设计的基础,包括图形的平移,旋转,缩放等操作,在数学上是通过矩阵来实现的。 1 glLoadIdentity过程 能够把当前矩阵变为单位矩阵。 2 glLoadMatrix过程 能够把指定的矩阵设为当前矩阵。 procedure glLoadmatrixd(m:GLdouble); procedure glLoadmatrixf(m:GLfloat); m表示4X4矩阵,下面的代码定义并使之成为当前矩阵 M:array[1..4,1..4] of GLfloat; glLoadMatrix(@M); 3 glMultMatrix过程 能够将当前矩与指定矩阵相乘,并把结果作为当前矩. procedure glMultMatrixd(M:GLdouble); procedure glMultMatrixf(M:GLfloat); 4 glPushMatrix和glPopmatrix glPushMatrix能够把当前矩压入矩阵堆栈, glPopMatrix能够把当前矩弹出矩阵堆栈. glPushMatrix能够记忆矩阵当前位置,glPopmatrix能够返回以前所在的位置. 注:glPushMatrix与glPopMatrix必须放在glBegin与glEnd之外. 5 投影变换 A glOrtho能够创建一个正投影矩阵,把当前矩乘以该正投影矩阵,其结果作为当前矩阵. function glOrtho(left:GLdouble,right:GLdouble,bottom:GLdouble,top:GLdouble, near:GLdouble,far:GLdouble); procedure TfrmMain.FormResize(Sender: TObject); var nRange:GLfloat; begin nRange:=50.0; w:=clientWidth; h:=clientHeight; if h=0 then h:=1; glViewPort(0,0,w,h); if w<=h then glOrtho(-nRange,nRange,-nRange*h/w,nRange*h/w, -nRange,nRange) else glOrtho(-nRange*h/w,nRange*h/w,-nRange,nRange, -nRange,nRange); repaint; end; B glOrtho2D只定义正投影视景体前,后,左,右. procedure glOrtho(left:GLdouble,right:GLdouble,bottom:GLdouble,top:GLdouble); C glMatrixMode过程 能够设置当前操作矩阵的类型 procedure glMatrixMode(mode:GLenum); mode的取值: GL_MODELVIEW 指定以后的矩阵操作为模型矩阵堆栈 GL_PROJECTION 指定以后的矩阵操作为投影矩阵堆栈 GL_TEXTURE 指定以后的矩阵操作为纹理矩阵堆栈 D glFrustum过程 创建一个透视斜投影矩阵,并把当前矩阵乘以该斜投影矩阵,其结果为当前矩阵. procedure glFrustum(left:GLdouble,right:GLdouble,bottom:GLdouble,top:GLdouble, next:GLdouble,far:GLdouble); 这些参数定义了斜投影的左,右,上,下,前,后剪裁面. E gluPerspective过程 能够定义一个以Z轴为中线的四棱台视景体. procedure gluPerspetive(fovy:GLdouble,aspect:GLdouble,zNear:GLdouble,zFar:GLdouble); fovy定义了xoz平面的视角,aspect定义了x和y方向上的比例,zNear和zFar分别定义了视点到剪裁面和后剪裁面的距离. procedure TfrmMain.FormResize(Sender: TObject); var aspect:GLfloat; begin w:=ClientWidth; h:=ClientHeight; if h=0 then h:=1; glViewPort(0,0,clientWidth,Clientheight); glMatrixMode(GL_PROJECTION); glLoadIdentity; aspect:=w/h; gluPerspective(30.0,aspect,1.0,50.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity; end; 6 几何变换矩阵 三维物体的运动姿态变换,是指物体的平移,旋转,缩放. A glTranslate过程能够把坐标原点移到(x,y,z),它的声明语法: procedure glTranslated(x:GLdouble,y:GLdouble,z:GLdouble); procedure glTranslatef(x:GLdouble,y:GLdouble,z:GLdouble); B glRotate能够使物体旋转一定的角度,它的声明语法: procedure glRotated(angle:GLdobule,x:GLdouble,y:GLdouble,z:GLdouble); procedure glRotatef(angle:GLdobule,x:GLdouble,y:GLdouble,z:GLdouble); 其中angle为旋转角,旋转的中心轴是由(0,0,0)与(x,y,z)两点的连线. C glScale能够对坐标系进行缩放,它的声明语法为: procedure glScaled(x:GLdouble,y:GLdoble,z:GLdouble); procedure glScalef(x:GLdouble,y:GLdoble,z:GLdouble); x,y,z的值大于1表示放大,小于1表示缩小. 例子原代码: unit MainFrm; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, OpenGL, ExtCtrls; type TfrmMain = class(TForm) Timer1: TTimer; procedure FormCreate(Sender: TObject); procedure FormDestroy(Sender: TObject); procedure FormPaint(Sender: TObject); procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); procedure FormResize(Sender: TObject); procedure Timer1Timer(Sender: TObject); procedure FormClose(Sender: TObject; var Action: TCloseAction); private { Private declarations } hrc:HGLRC; w,h:Integer; latitude,longitude:GLfloat; radius:GLdouble; public { Public declarations } procedure MyDraw; procedure InitializeGL(var width:GLsizei;height:GLsizei); end; var frmMain: TfrmMain; implementation {$R *.dfm} procedure TfrmMain.FormCreate(Sender: TObject); var pfd:TPixelFormatDescriptor; PixelFormat:Integer; begin ControlStyle:=ControlStyle+[csOpaque]; FillChar(pfd,sizeof(pfd),0); with pfd do begin nSize:=sizeof(TPixelFormatDescriptor); nVersion:=1; dwFlags:=PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER; iPixelType:=PFD_TYPE_RGBA; cColorBits:=24; cDepthBits:=32; iLayerType:=PFD_MAIN_PLANE; end; PixelFormat:=ChoosePixelFormat(Canvas.Handle,@pfd); SetPixelFormat(Canvas.Handle,PixelFormat,@pfd); hrc:=wglCreateContext(Canvas.Handle); w:=ClientRect.Right; h:=ClientRect.Bottom; InitializeGL(w,h); end; procedure TfrmMain.FormDestroy(Sender: TObject); begin wglDeleteContext(hrc); end; procedure TfrmMain.FormPaint(Sender: TObject); begin wglMakeCurrent(Canvas.Handle,hrc); glClearColor(1,1,1,1); glColor3f(1,0,0); glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); MyDraw; glFlush; end; procedure TfrmMain.MyDraw; var qObj:GLUQuadricObj; begin glPushMatrix; glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); glColor3f(1,0,0); glRotated(0.5,0.0,1.0,0.0); glRotated(-latitude,1.0,0.0,0.0); glrotated(longitude,0.0,0.0,1.0); qObj:=gluNewQuadric; gluQuadricDrawStyle(qObj,GLU_LINE); gluSphere(qObj,0.5,20,20); SwapBuffers(Canvas.Handle); end; {procedure TfrmMain.FormResize(Sender: TObject); var nRange:GLfloat; begin nRange:=50.0; w:=clientWidth; h:=clientHeight; if h=0 then h:=1; glViewPort(0,0,w,h); glMatrixMode(GL_PROJECTION); glLoadIdentity; if w<=h then glOrtho(-nRange,nRange,-nRange*h/w,nRange*h/w, -nRange,nRange) else glOrtho(-nRange*h/w,nRange*h/w,-nRange,nRange, -nRange,nRange); glMatrixMode(GL_MODELVIEW); glLoadidentity; repaint; end; } procedure TfrmMain.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); begin if Key=VK_ESCAPE then Close; if Key=VK_UP then glRotatef(-5,1.0,0.0,0.0); if Key=VK_DOWN then glRotatef(5,1.0,0.0,0.0); if Key=VK_LEFT then glRotatef(-5,0.0,1.0,0.0); if Key=VK_RIGHT then glRotatef(5.0,0.0,1.0,0.0); repaint; end; procedure TfrmMain.FormResize(Sender: TObject); begin glMatrixMode(GL_PROJECTION); glLoadIdentity; glFrustum(-1.0,1.0,-1.0,1.0,3.0,7.0); glViewPort(0,0,clientWidth,clientHeight); repaint; invalidate; end; procedure TfrmMain.InitializeGL(var width: GLsizei; height: GLsizei); var maxObjectSize,aspect:GLfloat; near_plane:GLdouble; begin glClearindex(0); glClearDepth(1.0); glEnable(GL_DEPTH_TEST); glMatrixMode(GL_PROJECTION); aspect:=1.0; gluPerspective(45.0,aspect,3.0,7.0); glmatrixMode(GL_MODELVIEW); near_plane:=0.3; maxObjectSize:=0.3; radius:=near_plane+maxObjectSize/2.0; latitude:=0.3; longitude:=0.6; end; procedure TfrmMain.Timer1Timer(Sender: TObject); begin timer1.Enabled:=false; MyDraw; Yield; Timer1.Enabled:=true; end; procedure TfrmMain.FormClose(Sender: TObject; var Action: TCloseAction); begin timer1.Enabled:=false; if hrc<>null then wglDeleteContext(hrc); end; end. 七、OPENGL的光照与纹理 都是增强三维立体效果和色彩效果的手段,光照能够增加图形的亮度和三维效果,纹理能够使用图形更加趋近现实。通过使用光照,可以将物体的外观很强列的表现出来,纹理则可以使物体显示多种多样的外观。 1 光照和光源过程及应用 A glIndex过程能够使颜色索引表中的某一种颜色成为当前颜色。 procedure glIndexd(c:GLdouble); procedure glIndexf(c:GLdouble); procedure glIndexi(c:GLdouble); procedure glIndexs(c:GLdouble); 参数C为索引值,如果使用glIndex过程,则TPiexlFormatDescriptor结构中的iPixelType成员设置为PFD_TYPE_COLORINDEX。 B glShadeModel过程 glShadeModel过程设置填充模式,取值:GL_SMOOTH. procedure glShadeModel(mode:GLenum); 注:以上两个过程只能在glBegin.....glEnd之外使用。 C glLight过程定义光源 procedure glLightf(light:GLenum,pname:GLenum,param:GLfloat); procedure glLighti(light:GLenum,pname:GLenum,param:GLfloat); 参数light定义光源,其值可取:GL_LIGHT0.....GL_LIGHTN,N值小于GL_MAX_LIGHT. 参数pname指定光源参数: GL_AMBIENT 环境光的分量强度 GL_DIFFUSE 散射光的分量强度 GL_SPECULAR 反射光的分量强度 GL_POSITION 光源位置 GL_SPOT_DIRECTION 光源的聚光方向 GL_SPOT_EXPONENT 光源的聚光指数 GL_SPOT_CUTOFF 光源的聚光方向 GL_CONSTANT_ATTENUATION 光常数衰退因子 GL_LINEAR_ATTENUATION 光二次衰减因子 启用和关闭光源使用glEnable()与glDisable()过程 glEnable(GL_LIGHTING); //启用光源 glDisable(GL_LIGHTING); //关闭光源 glEnable(GL_LIGHT0); //启用第0个光源 glDisable(GL_LIGHT0); //关闭第0个光源 设置光源的实例: var sdirection:Array[1..4] of GLfloat:={0.0,1.0,0.0,0.0}; glLightfv(GL_LIGHT0,GL_SPOT_CUTOFF,60); glLightfv(GL_LIGHT0,GL_SPOT_DIRECTION,sdirection); 2 材质和光照模型 A glMaterial过程设置材质参数 procedure glMaterialf(face:GLenum,pname :GLenum,param:GLfloat); procedure glMateriali(face:GLenum,pname :GLenum,param:GLfloat); procedure glMaterialfv(face:GLenum,pname :GLenum,param:GLfloat); procedure glMaterialiv(face:GLenum,pname :GLenum,param:GLfloat); 参数face指定物体表面,它的取值:GL_FRONT,GL_BACK,GL_FRONT_BACK. pname,param本资料没作介绍. B glLightModel过程 procedure glLightModelf(pname:GLenum,param:GLfloat); 参数pname为光源模型参数,可以取值GL_LIGHT_MODEL_AMBIENT, GL_LIGHT_MODEL_LOCAL_VIEWER,GL_LIGHT_MODEL_TWO_SIDE. 实例代码: procedure TfrmMain.SetLighting; var MaterialAmbient:array[1..4] of GLfloat; MaterialDiffuse:Array[1..4] of GLfloat; MaterialSpecular:Array[1..4] of GLfloat; AmbientLightPosition:Array[1..4] of GLfloat; LightAmbient:Array[1..4] of GLfloat; MaterialShininess:GLfloat; begin MaterialAmbient[1]:=0.5; MaterialAmbient[2]:=0.8; MaterialAmbient[1]:=0.2; MaterialAmbient[1]:=1.0; MaterialDiffuse[1]:=0.4; MaterialDiffuse[2]:=0.8; MaterialDiffuse[3]:=0.1; MaterialDiffuse[4]:=1.0; MaterialSpecular[1]:=1.0; MaterialSpecular[2]:=0.5; MaterialSpecular[3]:=0.1; MaterialSpecular[4]:=1.0; materialShininess:=50.0; AmbientLightPosition[1]:=0.5; AmbientLightPosition[2]:=1.0; AmbientLightPosition[3]:=1.0; AmbientLightPosition[4]:=0.0; LightAmbient[1]:=0.5; LightAmbient[2]:=0.2; LightAmbient[3]:=0.8; LightAmbient[4]:=1.0; glMaterialfv(GL_FRONT,GL_AMBIENT,@MaterialAmbient); glMaterialfv(GL_FRONT,GL_DIFFUSE,@MaterialDiffuse); glMaterialfv(GL_FRONT,GL_SPECULAR,@MaterialSpecular); glMaterialfv(GL_FRONT,GL_SHININESS,@MaterialShininess); glLightfv(GL_LIGHT0,GL_POSITION,@AmbientLightPosition); glLightModelfv(GL_LIGHT_MODEL_AMBIENT,@LightAmbient); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); GLShadeModel(GL_SMOOTH); end; 3 纹理的应用 A glTexImage1D定义一维纹理映射. procedure glTexImage1D(target:GLenum,level:GLint,components:GLint,width:GLsizei, border:GLint,format:GLenum,type:GLenum,pixels:GLvoid); 参数targer值为GL_TEXTURE_1D,定义为纹理映射,level为多级分辨率的纹理图像的等级,width为纹理宽,值为2n,n取值为32,64,129等.border为纹理的边界,其值为0或1,Pixel为纹理在内存中的位置.Component指定RGBA的混合和调整: 1 选择B成分 2 选择B,A成分 3 选择R,G,B成分 4 选择R,G,B,A成分 B glTexImage2D定义二维纹理映射 procedure glTexImage2D(target:GLenum,level:GLint,components:GLint,width:GLsizei, border:GLint,format:GLenum,type:GLenum,pixels:GLvoid); 若参数target为GL_TEXTURE_2D,意义为二维纹理映射,height为纹理的高,函数中的其它参数与glTexImage1D相同.component参数取值同上. 实例代码: procedure TfrmMain.SetTextures; var bits:Array[1..64,1..64,1..64] of GLubyte; bmp:TBitmap; i,j:Integer; begin bmp:=TBitmap.Create; bmp.LoadFromFile('d:\dsoft\1119\01\logon.bmp'); for i:=1 to 64 do for j:=1 to 64 do begin bits[i,j,1]:=GLbyte(GetRValue(bmp.Canvas.Pixels[i,j])); bits[i,j,2]:=GLbyte(GetRValue(bmp.Canvas.Pixels[i,j])); bits[i,j,3]:=GLbyte(GetRValue(bmp.Canvas.Pixels[i,j])); bits[i,j,4]:=255; end; {0代表为单色着色水平,GL_RGBA表示混合值 64X64代表纹理的高和宽,0表示无边界, GL_RGBA代表纹理类型,GL_UNSIGNED_TYPE代表数据类型,@代对象地址} glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,64,64,0,GL_RGBA, GL_UNSIGNED_BYTE,@bits); glEnable(GL_TEXTURE_2D); end; C glTexParameter过程设置纹理参数 procedure glTexParameterf(target:GLenum,pname:GLenum,param:GLfloat); procedure glTexParameteri(target:GLenum,pname:GLenum,param:GLfloat); 参数target代表GL_TEXTURE_1D或GL_TEXTURE_2D,param为纹理值. D glTexEnv函数设置纹理的环境参数 function glTexEnvf(target:GLenum,pname:GLenum,param:GLfloat); function glTexEnvi(target:GLenum,pname:GLenum,param:GLfloat); 参数target为GL_TEXTURE_ENV, 参数pname为纹理参数值,取值为GL_TEXTURE_ENV_MODE 参数param为环境值,取值为GL_MODULATE,GL_DECAL和GL_BLEND. 本程序示例代码: unit MainFrm; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, OpenGL, ExtCtrls; type TfrmMain = class(TForm) Timer1: TTimer; procedure FormCreate(Sender: TObject); procedure FormDestroy(Sender: TObject); procedure FormPaint(Sender: TObject); procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); procedure FormResize(Sender: TObject); procedure Timer1Timer(Sender: TObject); procedure FormClose(Sender: TObject; var Action: TCloseAction); private { Private declarations } hrc:HGLRC; w,h:Integer; latitude,longitude:GLfloat; radius:GLdouble; public { Public declarations } procedure SetLighting; procedure SetTextures; procedure MyDraw; procedure InitializeGL(var width:GLsizei;height:GLsizei); end; var frmMain: TfrmMain; implementation {$R *.dfm} procedure TfrmMain.FormCreate(Sender: TObject); var pfd:TPixelFormatDescriptor; PixelFormat:Integer; begin ControlStyle:=ControlStyle+[csOpaque]; FillChar(pfd,sizeof(pfd),0); with pfd do begin nSize:=sizeof(TPixelFormatDescriptor); nVersion:=1; dwFlags:=PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER; iPixelType:=PFD_TYPE_RGBA; cColorBits:=24; cDepthBits:=32; iLayerType:=PFD_MAIN_PLANE; end; PixelFormat:=ChoosePixelFormat(Canvas.Handle,@pfd); SetPixelFormat(Canvas.Handle,PixelFormat,@pfd); hrc:=wglCreateContext(Canvas.Handle); w:=ClientRect.Right; h:=ClientRect.Bottom; InitializeGL(w,h); end; procedure TfrmMain.FormDestroy(Sender: TObject); begin wglDeleteContext(hrc); end; procedure TfrmMain.FormPaint(Sender: TObject); begin wglMakeCurrent(Canvas.Handle,hrc); glClearColor(1,1,1,1); glColor3f(1,0,0); glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); SetTextures; MyDraw; SetLighting; glFlush; end; procedure TfrmMain.MyDraw; var qObj:GLUQuadricObj; begin glPushMatrix; glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT); glColor3f(1,0,0); glRotated(0.5,0.0,1.0,0.0); glRotated(-latitude,1.0,0.0,0.0); glrotated(longitude,0.0,0.0,1.0); qObj:=gluNewQuadric; gluQuadricDrawStyle(qObj,GLU_LINE); gluSphere(qObj,0.5,20,20); SwapBuffers(Canvas.Handle); SetLighting; SetTextures; end; {procedure TfrmMain.FormResize(Sender: TObject); var nRange:GLfloat; begin nRange:=50.0; w:=clientWidth; h:=clientHeight; if h=0 then h:=1; glViewPort(0,0,w,h); glMatrixMode(GL_PROJECTION); glLoadIdentity; if w<=h then glOrtho(-nRange,nRange,-nRange*h/w,nRange*h/w, -nRange,nRange) else glOrtho(-nRange*h/w,nRange*h/w,-nRange,nRange, -nRange,nRange); glMatrixMode(GL_MODELVIEW); glLoadidentity; repaint; end; } procedure TfrmMain.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); begin if Key=VK_ESCAPE then Close; if Key=VK_UP then glRotatef(-5,1.0,0.0,0.0); if Key=VK_DOWN then glRotatef(5,1.0,0.0,0.0); if Key=VK_LEFT then glRotatef(-5,0.0,1.0,0.0); if Key=VK_RIGHT then glRotatef(5.0,0.0,1.0,0.0); repaint; end; procedure TfrmMain.FormResize(Sender: TObject); begin glMatrixMode(GL_PROJECTION); glLoadIdentity; glFrustum(-1.0,1.0,-1.0,1.0,3.0,7.0); glViewPort(0,0,clientWidth,clientHeight); repaint; invalidate; end; procedure TfrmMain.InitializeGL(var width: GLsizei; height: GLsizei); var maxObjectSize,aspect:GLfloat; near_plane:GLdouble; begin glClearindex(0); glClearDepth(1.0); glEnable(GL_DEPTH_TEST); glMatrixMode(GL_PROJECTION); aspect:=1.0; gluPerspective(45.0,aspect,3.0,7.0); glmatrixMode(GL_MODELVIEW); near_plane:=0.3; maxObjectSize:=0.3; radius:=near_plane+maxObjectSize/2.0; latitude:=0.3; longitude:=0.6; end; procedure TfrmMain.Timer1Timer(Sender: TObject); begin timer1.Enabled:=false; MyDraw; Yield; Timer1.Enabled:=true; end; procedure TfrmMain.FormClose(Sender: TObject; var Action: TCloseAction); begin timer1.Enabled:=false; if hrc<>null then wglDeleteContext(hrc); end; procedure TfrmMain.SetLighting; var MaterialAmbient:array[1..4] of GLfloat; MaterialDiffuse:Array[1..4] of GLfloat; MaterialSpecular:Array[1..4] of GLfloat; AmbientLightPosition:Array[1..4] of GLfloat; LightAmbient:Array[1..4] of GLfloat; MaterialShininess:GLfloat; begin MaterialAmbient[1]:=0.5; MaterialAmbient[2]:=0.8; MaterialAmbient[1]:=0.2; MaterialAmbient[1]:=1.0; MaterialDiffuse[1]:=0.4; MaterialDiffuse[2]:=0.8; MaterialDiffuse[3]:=0.1; MaterialDiffuse[4]:=1.0; MaterialSpecular[1]:=1.0; MaterialSpecular[2]:=0.5; MaterialSpecular[3]:=0.1; MaterialSpecular[4]:=1.0; materialShininess:=50.0; AmbientLightPosition[1]:=0.5; AmbientLightPosition[2]:=1.0; AmbientLightPosition[3]:=1.0; AmbientLightPosition[4]:=0.0; LightAmbient[1]:=0.5; LightAmbient[2]:=0.2; LightAmbient[3]:=0.8; LightAmbient[4]:=1.0; glMaterialfv(GL_FRONT,GL_AMBIENT,@MaterialAmbient); glMaterialfv(GL_FRONT,GL_DIFFUSE,@MaterialDiffuse); glMaterialfv(GL_FRONT,GL_SPECULAR,@MaterialSpecular); glMaterialfv(GL_FRONT,GL_SHININESS,@MaterialShininess); glLightfv(GL_LIGHT0,GL_POSITION,@AmbientLightPosition); glLightModelfv(GL_LIGHT_MODEL_AMBIENT,@LightAmbient); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); GLShadeModel(GL_SMOOTH); end; procedure TfrmMain.SetTextures; var bits:Array[1..64,1..64,1..64] of GLubyte; bmp:TBitmap; i,j:Integer; begin bmp:=TBitmap.Create; bmp.LoadFromFile('d:\dsoft\1119\02\logon.bmp'); for i:=1 to 64 do for j:=1 to 64 do begin bits[i,j,1]:=GLbyte(GetRValue(bmp.Canvas.Pixels[i,j])); bits[i,j,2]:=GLbyte(GetRValue(bmp.Canvas.Pixels[i,j])); bits[i,j,3]:=GLbyte(GetRValue(bmp.Canvas.Pixels[i,j])); bits[i,j,4]:=255; end; glPixelStorei(GL_UNPACK_ALIGNMENT,4); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST); {0代表为单色着色水平,GL_RGBA表示混合值 64X64代表纹理的高和宽,0表示无边界, GL_RGBA代表纹理类型,GL_UNSIGNED_TYPE代表数据类型,@代对象地址} glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,64,64,0,GL_RGBA, GL_UNSIGNED_BYTE,@bits); glEnable(GL_TEXTURE_2D); glTexEnvf(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_DECAL); end; end. |