图解opengl曲线和曲面绘制
VC6 下載
http://blog.csdn.net/bcbobo21cn/article/details/44200205
opengl環(huán)境配置
http://blog.csdn.net/bcbobo21cn/article/details/51044614#t4
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以下的demo工程
http://pan.baidu.com/s/1kVGmRAJ
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一?使用二維求值器繪制一個(gè)曲面
#include <windows.h> #include <GL/GLAUX.h> #include <GL/glut.h> #include <math.h> //GLfloat ctrlpoints[5][5][3] = {{{-2,0,0},{-1,1,0},{0,0,0},{1,-1,0},{2,0,0}}, //{{-2,0,-1},{-1,1,-1},{0,0,-1},{1,-1,-1},{2,0,-1}}, //{{-2,0,-2},{-1,1,-2},{0,0,-2},{1,-1,-2},{2,0,-2}}, //{{-2,0,-3},{-1,1,-3},{0,0,-3},{1,-1,-3},{2,0,-3}}, //{{-2,0,-4},{-1,1,-4},{0,0,-4},{1,-1,-4},{2,0,-4}}};GLfloat ctrlpoints[5][5][3] = {{{-3,0,0},{-1,1,0},{0,0,0},{1,-1,0},{3,0,0}}, {{-3,0,-1},{-1,1,-1},{0,0,-1},{1,-1,-1},{3,0,-1}}, {{-3,0,-3},{-1,1,-3},{0,0,-3},{1,-1,-3},{3,0,-3}}, {{-3,0,-3},{-1,1,-3},{0,0,-3},{1,-1,-3},{3,0,-3}}, {{-3,0,-4},{-1,1,-4},{0,0,-4},{1,-1,-4},{3,0,-4}}};GLfloat mat_ambient[] = {0.1,0.1,0.1,1.0}; GLfloat mat_diffuse[] = {1.0,0.6,0.0,1.0}; GLfloat mat_specular[] = {1.0,1.0,1.0,1.0};GLfloat light_ambient[] = {0.1,0.1,0.1,1.0}; //GLfloat light_diffuse[] = {1.0,1.0,1.0,0.0}; GLfloat light_diffuse[] = {0.2,1.0,0.2,0.0}; GLfloat light_specular[] = {1.0,1.0,1.0,0.0}; GLfloat light_position[] = {2.0,23.0,-4.0,1.0};void myInit(void) {glClearColor(0.0,0.0,0.0,0.0);//設(shè)置背景色/*為光照模型指定材質(zhì)參數(shù)*/glMaterialfv(GL_FRONT,GL_AMBIENT,mat_ambient);glMaterialfv(GL_FRONT,GL_DIFFUSE,mat_diffuse);glMaterialfv(GL_FRONT,GL_SPECULAR,mat_specular);glMaterialf(GL_FRONT,GL_SHININESS,60.0);/*設(shè)置光源參數(shù)*/glLightfv(GL_LIGHT0,GL_AMBIENT,light_ambient);glLightfv(GL_LIGHT0,GL_DIFFUSE,light_diffuse);glLightfv(GL_LIGHT0,GL_SPECULAR,light_specular);glLightfv(GL_LIGHT0,GL_POSITION,light_position);glEnable(GL_LIGHTING);glEnable(GL_LIGHT0);/*enable depth comparisons and update the depth buffer*/glEnable(GL_DEPTH_TEST);/*設(shè)置特殊效果*/glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);glHint(GL_LINE_SMOOTH_HINT,GL_DONT_CARE);glEnable(GL_BLEND);glEnable(GL_AUTO_NORMAL);glEnable(GL_NORMALIZE);glFrontFace(GL_CW);glShadeModel(GL_SMOOTH);glEnable(GL_LINE_SMOOTH);}void myDisplay(void) {glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);glColor3f(0.4,0.4,0.4);glTranslatef(0.0,-1.0,0.0);glRotatef(50.0,1.0,0.0,0.0);glPushMatrix();/*繪制曲面*/glEnable(GL_MAP2_VERTEX_3);glMap2f(GL_MAP2_VERTEX_3,0,1,3,5,0,1,15,5,&ctrlpoints[0][0][0]);glMapGrid2f(10.0,0.0,1.0,10.0,0.0,1.0);glEvalMesh2(GL_FILL,0,10.0,0,10.0);glPopMatrix();glutSwapBuffers(); }void myReshape(GLsizei w,GLsizei h) {glViewport(0,0,w,h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluPerspective(60.0,(GLfloat)w/(GLfloat)h,1.0,100.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();glTranslatef(0.0,0.0,-5.0); }int main(int argc,char ** argv) {/*初始化*/glutInit(&argc,argv);glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB|GLUT_DEPTH);glutInitWindowSize(400,400);glutInitWindowPosition(200,200);/*創(chuàng)建窗口*/glutCreateWindow("lighted Bezier surface");/*繪制與顯示*/myInit();glutReshapeFunc(myReshape);glutDisplayFunc(myDisplay);/*進(jìn)入GLUT事件處理循環(huán)*/glutMainLoop();return(0); }?
void glMap2f(GLenum target,GLfloat u1,GLfloat u2,Glint ustride, Glint uorder, GLfloat v1, GLfloat v2, Glint vstride, Glint vorder, const GLfloat *points);
定義2維求值器。
target指定求值器生成的數(shù)值類型。本例中的GL_MAP2_VERTEX_3 指明每一個(gè)控制點(diǎn)為x、y、z表示的三個(gè)浮點(diǎn)值。
u1,u2指定線性映射。
ustride 指定控制點(diǎn)Rij的起始點(diǎn)和控制點(diǎn) R(i+1)j的的起始點(diǎn)之間單精度或雙精度浮點(diǎn)值的個(gè)數(shù)。這里i和j分別是u和v控制點(diǎn)索引,它允許控制點(diǎn)裝入任意的數(shù)據(jù)結(jié)構(gòu)中。唯一的限制是對(duì)于特定控制點(diǎn)的數(shù)值必須存在連續(xù)的內(nèi)存單元。
uorder控制點(diǎn)數(shù)組在u軸方向上的維數(shù)。
v1,v2指定線性映射v
vstride指定控制點(diǎn)Rij的起始點(diǎn)和控制點(diǎn) Ri(j+ 1)的起始點(diǎn)之間單精度或雙精度浮點(diǎn)值的個(gè)數(shù)。這里i和j分別是u和v控制點(diǎn)索引,它允許控制點(diǎn)裝入任意的數(shù)據(jù)結(jié)構(gòu)中。唯一的限制是對(duì)于特定控制點(diǎn)的數(shù)值必須存在連續(xù)的內(nèi)存單元。
vorder控制點(diǎn)數(shù)組在v軸方向上的維數(shù)。
points 一個(gè)指向控制點(diǎn)數(shù)組的指針。
glMapGrid定義一維或二維網(wǎng)格。
void glMapGrid2f(Glint un, GLfloat u1, GLfloat u2,Glint vn, GLfloat v1,GLfloat v2);
un 在網(wǎng)格[u1,u2]中的分段數(shù)目。
u1,u2 指定整數(shù)網(wǎng)格范圍 i= 0;i= un的映射。
vn在網(wǎng)格[v1,v2]中的分段數(shù)目。
v1,v2 指定整數(shù)網(wǎng)格范圍 j = 0;j= vn的映射。
glEvalMesh 計(jì)算一維或二維點(diǎn)或線網(wǎng)格。
void glEvalMesh2(GLenum mode,Glint i1,Glint i2,Glint j1,Glint j2);
mode 指定是否計(jì)算二維點(diǎn)、線或多邊形的網(wǎng)格。
i1,i2 分別為網(wǎng)格定義域變量i的第一個(gè)和最后一個(gè)整數(shù)值。
j1,j2分別為網(wǎng)格定義域變量j的第一個(gè)和最后一個(gè)整數(shù)值。
glMapGrid和glEvalMesh用來生成并求取一系列等間隔的網(wǎng)格點(diǎn),glEvalMesh逐步計(jì)算一維或二維網(wǎng)格,他的定義范圍由glMap指定。mode決定最終計(jì)算的頂點(diǎn)是繪制為點(diǎn)、線還是充實(shí)的多邊形。
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以下分別是兩組不同控制點(diǎn)的效果;控制點(diǎn)坐標(biāo)在代碼中;
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二?opengl繪制Bezier Curve
#include "gl/glut.h" int Line_Count = 80; // 線條數(shù)越大 曲面越平滑 // 線條數(shù)越小 曲面越粗糙 // 可以從 左下 右下 兩條曲線得到對(duì)比 // 左上曲線控制點(diǎn) GLfloat ControlPoints0[4][3] = { { -4.0 , 1.0 , 0.0 } , // 控制點(diǎn)在數(shù)組中的順序決定曲線樣式 { -1.0 , 1.0 , 0.0 } , { -1.0 , 4.0 , 0.0 } , { -4.0 , 4.0 , 0.0 } }; // 右上曲線控制點(diǎn) GLfloat ControlPoints1[4][3] = { { 4.0 , 1.0 , 0.0 } , { 1.0 , 4.0 , 0.0 } , { 1.0 , 1.0 , 0.0 } , { 4.0 , 4.0 , 0.0 } }; // 右下曲線控制點(diǎn) GLfloat ControlPoints2[4][3] = { { 1.0 , -4.0 , 0.0 } , { 4.0 , -4.0 , 0.0 } , { 1.0 , -1.0 , 0.0 } , { 4.0 , -1.0 , 0.0 } }; // 左下曲線控制點(diǎn) GLfloat ControlPoints3[4][3] = { { -4.0 , -4.0 , 0.0 } , { -1.0 , -4.0 , 0.0 } , { -4.0 , -1.0 , 0.0 } , { -1.0 , -1.0 , 0.0 } }; void Display( void ) { int i; glClear( GL_COLOR_BUFFER_BIT ); glLoadIdentity(); // 先繪制控制點(diǎn) 再繪制曲線 // 左上曲線 glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ControlPoints0[0][0]); glColor3f( 0 , 0 , 1.0 ); glBegin( GL_POINTS ); for( i = 0 ; i < 4 ; i++ ) { glVertex3fv( ControlPoints0[i] ); } glEnd(); glColor3f(0.0, 1.0, 0.0); glBegin( GL_LINE_STRIP ); for( i = 0 ; i <= Line_Count ; i++ ) { glEvalCoord1f( (GLfloat)i/Line_Count ); } glEnd(); // 右上曲線 glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ControlPoints1[0][0]); glColor3f( 1.0 , 0.0 , 0.0 ); glBegin( GL_POINTS ); for( i = 0 ; i < 4 ; i++ ) { glVertex3fv( ControlPoints1[i] ); } glEnd(); glColor3f(0.0, 1.0, 0.0); glBegin( GL_LINE_STRIP ); for( i = 0 ; i <= Line_Count ; i++ ) { glEvalCoord1f( (GLfloat)i/Line_Count ); } glEnd(); // 右下曲線 glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ControlPoints2[0][0]); glColor3f( 0.0 , 0.0 , 1.0 ); glBegin( GL_POINTS ); for( i = 0 ; i < 4 ; i++ ) { glVertex3fv( ControlPoints2[i] ); } glEnd(); glColor3f(0.0, 1.0, 0.0); glBegin( GL_LINE_STRIP ); for( i = 0 ; i <= Line_Count ; i++ ) { glEvalCoord1f( (GLfloat)i/Line_Count ); } glEnd(); // 左下曲線 Line_Count = 8; // 降低線條數(shù) 曲線變粗糙 glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, &ControlPoints3[0][0]); glColor3f( 1.0 , 1.0 , 0.0 ); glBegin( GL_POINTS ); for( i = 0 ; i < 4 ; i++ ) { glVertex3fv( ControlPoints3[i] ); } glEnd(); glColor3f(0.0, 1.0, 0.0); glBegin( GL_LINE_STRIP ); for( i = 0 ; i <= Line_Count ; i++ ) { glEvalCoord1f( (GLfloat)i/Line_Count ); } glEnd(); glFlush(); } void Initialize() { glClearColor( 0.0 , 0.0 , 0.0 , 0.0 ); glShadeModel( GL_SMOOTH ); glEnable(GL_MAP1_VERTEX_3); glEnable( GL_LINE_SMOOTH ); // 平滑線條 glPointSize( 6.0 ); // 把點(diǎn)變大一點(diǎn) 看的清楚 } void Reshape( int Width , int Height ) { glViewport( 0 , 0 , (GLsizei)Width , (GLsizei)Height ); glMatrixMode( GL_PROJECTION ); glLoadIdentity(); if( Width <= Height ) { glOrtho( -5.0 , 5.0 , -5.0 * (GLfloat)Height / (GLfloat)Width , 5.0 * (GLfloat)Height / (GLfloat)Width , -5.0 , 5.0 ); } else { glOrtho( -5.0 * (GLfloat)Width / (GLfloat)Height , 5.0 * (GLfloat)Width / (GLfloat)Height , -5.0 , 5.0 , -5.0 , 5.0 ); } glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); } void main() { glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB ); glutInitWindowSize( 700 , 700 ); glutInitWindowPosition( 162 , 34 ); glutCreateWindow( "Bezier Curve" ); Initialize(); glutDisplayFunc( Display ); glutReshapeFunc( Reshape ); glutMainLoop(); }?
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